New palladacycles containing terdentate [C,N,O]n- (n = 0, 1, 2) or tetradentate [N,C,O,N′]n- in = 1, 2 ligands. the first 1,2-dihydroquinazoline-4-yl complexes

3254

Organometallics 2008, 27, 3254–3271

New Palladacycles Containing Terdentate [C,N,O]^n-(n ) 0, 1, 2) or

Tetradentate [N,C,O,N′]^n-(n ) 1, 2) Ligands. The First

1,2-Dihydroquinazoline-4-yl Complexes

Jose´ Vicente, Mar´ıa Teresa Chicote,* and Antonio Jesu´s Mart´ınez-Mart´ınez

Grupo de Qu´ımica Organometa´lica, Departamento de Qu´ımica Inorga´nica, UniVersidad de Murcia,

Apartado 4021, 30071 Murcia, Spain

Peter G. Jones^‡

Institut fu¨r Anorganische and Analytische Chemie der Technischen UniVersita¨t Braunschweig, Postfach

23329, 38023, Braunschweig, Germany

Delia Bautista^§

SAI, UniVersidad de Murcia, Apartado 4021, 30071 Murcia, Spain

ReceiVed March 5, 2008

The reaction of IC₆H₄{NHC(Me)CHC(O)Me}-2 (IAr) with [Pd₂(dba)₃] · dba (“Pd(dba)₂”, dba )

dibenzylideneacetone) gives, in the presence of bidentate ligands N^N (1:1:1), cis-[PdI(Ar)(N^N)] (N^N

) 4,4′-tert-butyl-2,2′-bipyridine ) ^tBubpy (1), N,N,N′,N′-tetramethylethylenediamine ) tmeda (2)). These

complexes react with PPh₃(1:2) to give trans-[PdI(Ar)(PPh₃)₂] (3) or with TlTfO (TfO ) CF₃SO₃) to

t

give [Pd{C,C-C₆H₄{NHdC(Me)CHC(O)Me}-2}(N^N)]TfO (N^N ) Bubpy (4), tmeda (5)), which, in

turn, react with neutral monodentate ligands (L, 1:1) to give complexes [Pd(Ar)(N^N)(L)] (N^N ) ^tBubpy,

L ) PPh₃(6), N^N ) tmeda, L ) PPh₃(7), ^tBuNC (8)). The reaction of IAr with “Pd(dba)₂” and RNC

t

(R ) Xy, Bu) in 1:1:2 molar ratio produces a mixture containing [Pd₂I₂(CNXy)₄] (9, Xy ) C₆H₃Me₂-

2,6) or trans-[PdI₂{C(dNH^tBu)Ar}(CN^tBu)] (10), respectively, but using an excess of RNC (1:1:5 molar

ratio), complexes trans-[PdI{C(dNR)Ar}(CNR)₂] (R ) ^tBu (11), Xy (12)) are obtained instead. Complex

5reactswithXyNC(1:1)togivethedimericcomplex[Pd{µ-N,C,N′,O-N(Xy){dCC₆H₄{NC(Me)CHC(Me)O}-

2}}]₂(13), which reacts with excess HTfO to give [Pd{µ-N,C,N′,O-N(Xy){dCC₆H₄{NdC(Me)CH₂C(O)Me}-

2}}]₂(TfO)₂(14a) or with neutral monodentate ligands (L) to give neutral mononuclear pincer complexes

[Pd{C,N,O-C(dNXy)C₆H₄{NC(Me)CHC(Me)O}-2}(L)] (L ) PPh₃(15), ^tBuNC (16a), XyNC (17)), which

react with excess of HTfO to give the corresponding dicationic [Pd{C,N,O-C(dNHXy)C₆H₄{NdC-

(Me)CH₂C(O)Me}-2}(PPh₃)](TfO)₂(18) or monocationic pincer derivatives [Pd{C,N,O-

C(dNHXy)C₆H₄{NC(Me)CHC(Me)O}-2}(CNR)]TfO (R ) ^tBu (19), Xy (20)), respectively. The reaction

of complex 11 or 12 with AgClO₄(1:1) or that of 14a with PPh₃(1:2) affords [Pd{C,N,O-

C(dNHR)C₆H₄{NC(Me)CHC(Me)O}-2}L]X (X/R/L ) ClO₄/^tBu/^tBuNC (21), ClO₄/Xy/XyNC (22), TfO/

Xy/PPh₃(23)), analogues of 19 or 20, respectively. The reaction of 21 with Na₂CO₃(2:1) allowed the

synthesis of [Pd{C,N,O-C(dN^tBu)C₆H₄{NC(Me)CHC(Me)O}-2}(CN^tBu)] (16b). The reaction of 1 or 3

with HI and XyNC in 1:1:2 or 1:1:1 molar ratio, respectively, produces the ﬁrst 1,2-dihydroquinazoline-

4-yl complexes trans-[PdI₂{C(dNXy)C(Me){CH₂C(O)Me}NHC₆H₄-2}(L)] (L )XyNC (24), PPh₃(25)).

The crystal structures of complexes 1, 3, 5, 7, 10, 13, 14a, 17, 21, 22, and 24 have been determined.

Single crystals of complex [Pd{µ-O,N,C,N′-OC(Me)CHC(Me)NC₆H₄CdNXy}{µ-N,C,N′,O-

N(Xy){dCC₆H₄{NC(Me)CH₂C(Me)O}-2}}]TfO (14b) were obtained alongside those of 14a, and the

corresponding crystal structure was also solved.

complexes that could display interesting activity in areas such

as organic synthesis, catalysis, or materials science.^1a–dIn

addition to classical palladacycles with monoanionic bidentate

ligands, interest is growing in cyclometalated palladium com-

pounds containing terdentate ligands that impose severe restric-

tions on the coordination sphere of the metal, thus modifying

its reactivity.^1e–g

One of our research interests is the synthesis of ortho-

functionalized arylpalladium complexes and the study of their

reactivity toward unsaturated molecules such as CO, isocyanides,

alkenes, alkynes, or carbodiimides. The ability of the Pd-C

bond to insert unsaturated molecules is thought to be one of

Introduction

In the chemistry of palladium, the search for multidentate

ligands has been increasing during the past few years mainly

with the purpose of preparing tailor-made organometallic

* To whom correspondence should be addressed. E-mail: mch@um.es.

WWW: http://www.um.es/gqo/.

^‡To whom correspondence regarding the X-ray diffraction studies of

complexes 1, 5, 7, 10, 14a, 14b, 21, 22, and 24, should be addressed. E-mail:

p.jones@tu-bs.de.

^§To whom correspondence regarding the X-ray diffraction study of

complexes 3, 13, and 17 should be addressed. E-mail: dbc@um.es.

10.1021/om800205g CCC: $40.75

2008 American Chemical Society

Publication on Web 06/06/2008

The First 1,2-Dihydroquinazoline-4-yl Complexes

Organometallics, Vol. 27, No. 13, 2008 3255

Chart 1

the key steps in many palladium-catalyzed reactions. We believe

that synthesizing and studying such species could open the way

to the discovery of new reactivity patterns. Our studies in this

ﬁeld over the past few years have given us the opportunity to

prepare novel types of organometallic complexes as well as

various organic products.^1h–kIn particular, we described recently

a Pd-C,N,C-pincer complex that is an efﬁcient precatalyst in

Heck and Suzuki cross-coupling processes.²In addition, the

present study involves formation of ortho-substituted aryl

complexes that must be intermediates in a reported palladium-

catalyzed synthesis of 2,3-disubstituted indoles.^3a

Quite a few palladium complexes with terdentate C,N,O-

ligands have been reported.^{1a,3b–l,4–9}In most cases they have

been prepared by treating an appropriate hydrazone, semicar-

bazone, imine, quinoline, or diarylazo derivative with

[Pd(OAc)₂] or with Li₂[PdCl₄], sometimes in the presence of a

base. The carbon atom bonded to Pd is generally sp²hybridized

and, in most cases, belongs to an aryl ligand. In a few examples,

it belongs to thiophene,⁴pyrrole,⁵or ferrocenyl^7a,7b,8,9fragments,

and only one Pd-C(sp³)NO pincer complex has been reported.⁶

In the majority of such complexes both the Pd-O-N and

Pd-C-N cycles are ﬁve-membered, although a few examples

are known for Pd-O-N in which there are six-membered

rings.⁷Two complexes have also been reported with Pd-O-N

and Pd-C-N in six- and seven-membered rings, respectively,

the latter resulting from the insertion of RCt CR (R ) Ph,⁸

CO₂Me)⁹into a Pd-C_ferrocenylbond.

disposition of its potential donor atoms, which, after the insertion

of unsaturated molecules into the Pd-C_arylbond, could lead to

novel types of pincer complexes. In fact, 10 new ligands are

present in the complexes here described, including aryl, imi-

noacyl, mono- and dianionic C,N,O-pincer, and 1,2-dihydro-

quinazolin-4-yl ligands, some of which are connected through

a rich acid/base chemistry.

Experimental Section

When not otherwise stated, the reactions were carried out without

precautions to exclude light or atmospheric oxygen or moisture.

Melting points were determined on a Reicher apparatus and are

uncorrected. Elemental analyses were carried out with a Carlo Erba

1106 microanalyzer. Molar conductivities were measured on a ca.

5 × 10^-4mol · L^-1acetone solution with a Crison Micro CM2200

conductimeter. IR spectra were recorded on a Perkin-Elmer 16F

PC FT-IR spectrometer with Nujol mulls between polyethylene

sheets. NMR spectra were recorded in Varian 200, 300, or 400

NMR spectrometers. Chemical shifts are referred to TMS (¹H, ¹³C)

or H₃PO₄(³¹P). The NMR assignments follow the atom-numbering

scheme depicted in Chart 1 and, in some cases, were performed

with the help of APT, HMQC, and HMBC experiments.

[Pd₂(dba)₃] · dba [Pd(dba)₂, dba ) dibencylideneacetone] was

prepared as reported in the literature,¹⁰TlTfO was obtained from

HTfO (TfO ) CF₃SO₃) and Tl₂CO₃(Fluka), tmeda, XyNC, ^tBuNC,

In this paper we report the reactivity of a functionalized aryl

ligand (see Chart 1), selected in view of the nature and

(1) (a) Solé, D.; Díaz, S.; Soláns, X.; Font-Bardía, M. Organometallics

2006, 25, 1995. (b) Dupont, J.; Consorti, C. S.; Spencer, J. Chem. ReV.

2005, 105, 2527. (c) Bedford, R. B. Chem. Commun. 2003, 1787. (d)

Dupont, J.; Pfeffer, M.; Spencer, J. Eur. J. Inorg. Chem. 2001, 1917. (e)

Albrecht, M.; van Koten, G. Angew. Chem., Int. Ed. Engl. 2001, 40, 3750.

(f) van der Boom, M. E.; Milstein, D. Chem. ReV. 2003, 103, 1759. (g)

Singleton, J. T. Tetrahedron 2003, 59, 1837. (h) Vicente, J.; Abad, J. A.;

López-Sáez, M. J.; Jones, P. G. Organometallics 2006, 25, 1851. (i) Vicente,

J.; Abad, J. A.; López-Nicolás, R. M. Tetrahedron Lett. 2005, 46, 5839. (j)

Vicente, J.; Abad, J. A.; Foertsch, W.; López-Sáez, M. J.; Jones, P. G.

Organometallics 2004, 23, 4414. (k) Vicente, J.; Abad, J. A.; López-Serrano,

J.; Jones, P. G. Organometallics 2004, 23, 4711.

t

and PPh₃were purchased from Fluka, Bubpy and AgClO₄· H₂O

(2) Vicente, J.; Abad, J. A.; Lo´pez-Serrano, J.; Jones, P. G.; Na´jera, C.;

Botella-Segura, L. Organometallics 2005, 5044.

were purchased from Aldrich, and HI (57%) was purchased from

Riedel de Hae¨n. The solvents were distilled before use.

(3) (a) Sakamoto, T.; Nagano, T.; Kondo, Y.; Yamanaka, H. Synthesis

1990, 215. (b) Nonoyama, M.; Sugimoto, M. Inorg. Chim. Acta 1979, 35,

131. (c) Tollari, S.; Palmisano, G.; Demartin, F.; Grassi, M.; Magnaghi,

S.; Cenini, S. J. J. Organomet. Chem. 1995, 488, 79. (d) Vila, J. M.; Pereira,

T.; Ortigueira, J. M.; Torres, M. L.; Castiñeiras, A.; Lata, D.; Ferna´ndez, J. J.;

Fernandez, A. J. Organomet. Chem. 1998, 556, 21. (e) Fernández, A.; López-

Torres, M.; Suárez, A.; Ortigueira, J. M.; Pereira, T.; Fernández, J. J.; Vila,

J. M.; Adams, H. J. Organomet. Chem. 2000, 598, 1. (f) Das, S.; Pal, S. J.

J. Organomet. Chem. 2004, 689, 352. (g) Albert, J.; González, A.; Granell,

J.; Moragas, R.; Puerta, C.; Valerga, P. Organometallics 1997, 16, 3775.

(h) Albert, J.; González, A.; Granell, J.; Moragas, R.; Solans, X.; Font

Bardia, M. J. Chem. Soc. Dalton Trans. 1998, 1781. (i) Cativiela, C.;

Falvello, L. R.; Gines, J. C.; Navarro, R.; Urriolabeitia, E. P. New J. Chem.

2001, 25, 344. (j) Fernández, A.; Pereira, E.; Fernández, J. J.; López-Torres,

M.; Suarez, A.; Mosteiro, R.; Vila, J. M. Polyhedron 2002, 21, 39. (k)

Fernández, A.; Vázquez-Garcia, D.; Fernández, J. J.; López-Torres, M.;

Suárez, A.; Castro-Juiz, S.; Vila, J. M. New J. Chem. 2002, 26, 398. (l)

Steiner, E.; L’Epplattenier, F. A. HelV. Chim. Acta 1978, 61, 2264.

(4) Nonoyama, M. J. Inorg. Nucl. Chem. 1980, 42, 297.

Synthesis of IC₆H₄NHC(Me)CHC(O)Me-2 (IAr; 4-(2-io-

dophenylamino)pent-3-en-2-one). In order to avoid the use of

benzene, we have slightly modiﬁed the procedure reported by

Sakamoto.³To a solution of 2-iodoaniline (10.64 g, 48.6 mmol) in

a mixture of CHCl₃and EtOH (70/20, v/v) were added freshly

distilled acetylacetone (5 mL, 48.6 mmol), p-toluenesulfonic acid

monohydrate (1 g, 5.26 mmol), and anhydrous MgSO₄(10 g). The

reaction mixture was reﬂuxed for 6 h and ﬁltered. The yellow

solution was concentrated to dryness. The oily residue was dissolved

in CHCl₃(30 mL) and washed with H₂O (3 × 20 mL). The organic

layer was dried over anhydrous MgSO₄and concentrated to give

an oily material. Upon the addition of Et₂O (1 mL) and n-hexane

(10 mL) and cooling the solution at -30 °C overnight, colorless

crystals of IAr formed, which were ﬁltered off and suction dried.

1

Yield: 7.6 g, 52%. Mp: 56 °C. H NMR (400 MHz, CDCl₃): δ

(5) Nonoyama, M. Inorg. Chim. Acta 1988, 145, 53.

1.85 (s, 3 H, MeCN), 2.13 (s, 3 H, C(O)Me), 5.25 (s, 1 H, CH),

3

4

(6) Yoneda, A.; Hakushi, T.; Newkome, G. R.; Fronczek, F. R.

Organometallics 1994, 13, 4912.

6.92 (td, 1 H, H15, J_HH) 8 Hz, J_HH) 1 Hz), 7.16 (dd, 1 H,

H16, ³J_HH) 8 Hz, ⁴J_HH) 1 Hz), 7.33 (td, 1 H, H14, ³J_HH) 8 Hz,

(7) (a) Zhao, G.; Wang, Q.-G.; Mak, T. C. W. J. Chem. Soc., Dalton

Trans. 1998, 3785. (b) Zhao, G.; Wang, Q.-G.; Mak, T. C. W. Organo-

metallics 1998, 17, 3437. (c) Yang, H.; Khan, M. A.; Nicholas, K. M.

J. Chem. Soc., Chem. Commun. 1992, 210.

⁴J_HH) 1 Hz), 7.87 (dd, 1 H, H13, J_HH) 8 Hz, J_HH) 1 Hz),

12.29 (s, 1 H, NH). ¹³C{¹H} NMR (50 MHz, CDCl₃): δ 19.6

(MeCN), 29.2, (C(O)Me), 97.5 (C11), 97.7 (C2), 127.0 (C15), 127.7

3

4

(8) Zhao, G.; Wang, Q. G.; Mak, T. C. W. J. Organomet. Chem. 574,

311-317 1999, 574, 311.

(9) Perez, S.; Lopez, C.; Caubet, A.; Solans, X.; Font-Bardia, M.; Roig,

A.; Molins, E. Organometallics 2006, 25, 596.

(10) Takahashi, Y.; Ito, T.; Sakai, S.; Ishii, U. J. Chem. Soc., Chem.

Commun. 1970, 1065.

3256 Organometallics, Vol. 27, No. 13, 2008

Vicente et al.

(C16), 128.7 (C14), 139.4 (C13), 140.9 (C12), 159.6 (C1), 196.5

N ) 9 Hz), 142.4 (vt, C, Ar, N ) 6 Hz), 151.8 (vt, C, Ar, N ) 7

Hz), 157.3 (C1), 193.5 (CO). ³¹P{¹H} NMR (162 MHz, CDCl₃):

δ 21.3. IR (cm^-1): ν_CdO1600. Anal. Calcd for C₄₇H₄₂INOP₂Pd:

C, 60.56; H, 4.54; N, 1.50. Found: C, 60.68; H, 4.86; N, 1.62.

Crystals of 3 · 0.89CH₂Cl₂· 0.55Et₂O suitable for an X-ray diffrac-

tion study were obtained by the liquid diffusion method using

CH₂Cl₂and Et₂O.

(CO). IR (cm^-1): ν_CdO1610.

Synthesis of [PdI(Ar)(N^N)] [N^N ) ^tBubpy (1), tmeda (2)].

To a suspension of Pd(dba)₂(mg/mmol for 1: 183.6/0.32, for 2:

225.0/0.39) in toluene (20 mL), under a nitrogen atmosphere, were

added the appropriate bidentate ligand (N^N/mg/mmol for 1: ^tBubpy

) 4,4′-tert-butyl-2,2′-bipyridine/85.7/0.32, for 2: tmeda ) N,N,N′,N′-

tetramethylethylenediamine/45.5/0.39) and IAr (mg/mmol for 1:

96.1/0.32, for 2: 117.8/0.39) with an interval of 10 min. The reaction

mixture was stirred (1: 2.5 h; 2: 2 h) and concentrated under vacuum

to dryness, and the solid residue was stirred with CH₂Cl₂(20 mL).

The resulting suspension was ﬁltered through a short pad of Celite

to remove some metallic palladium, and the orange (1) or yellow

(2) ﬁltrate was concentrated to ca. 2 mL. Upon the addition of Et₂O

(5 mL) and n-hexane (20 mL), 1 precipitated along with some dba.

The crude product was reﬂuxed in n-hexane (30 mL) for 15 min,

and the suspension was ﬁltered while hot. The yellow solid collected

was recrystallized from CH₂Cl₂/Et₂O and air-dried to give pure 1.

In the case of 2, Et₂O (30 mL) was added, and the resulting

suspension was stirred in a water/ice bath for 30 min to convert

the initially oily material into a yellow solid that was ﬁltered off,

recrystallized from CH₂Cl₂/Et₂O, and suction dried.

Synthesis of [Pd{C,C-C₆H₄{NHdC(Me)CHC(O)Me}-2}(N^N)]-

t

TfO [N^N ) Bubpy (4), tmeda (5)]. To a solution of 1 or 2

(mg/mmol for 4: 300/0.44, for 5: 99/0.19, respectively) in acetone

(20 mL) was added TlTfO (mg/mmol: 156.9/0.44 mmol, 67.2/0.19,

respectively). A suspension immediately formed that was stirred

for 2 (4) or 1 (5) h and ﬁltered through a short pad of Celite. The

solution was concentrated under vacuum to ca. 1 mL, and Et₂O

(20 mL) was added to precipitate an oily material, which was

converted into a pale yellow powder by stirring the suspension in

an ice/water bath for 15 min. The suspension was ﬁltered and the

yellow solid was recrystallized from CH₂Cl₂/Et₂O (4) or acetone/

Et₂O (5) and suction dried.

4. Yield: 113 mg, 77%. Mp: 176 °C (dec). ¹H NMR (400 MHz,

acetone-d₆, - 60 °C): δ 1.38 (s, 9 H, ^tBu), 1.42 (s, 9 H, ^tBu), 2.14

(s, 3 H, C(O)Me), 2.65 (s, 3 H, MeCN), 4.46 (s, 1 H, CH),

7.10-7.20 (m, 4 H, Ar), 7.85 (d, 1 H, H25 or H35, ³J_HH) 6 Hz),

1. Yield: 140 mg, 67%. Mp: 182 °C. ¹H NMR (300 MHz,

t

3

CDCl₃): δ 1.38 (s, 9 H, Bu), 1.41 (s, 9 H, Bu), 1.90 (s, 3 H,

MeCN), 1.99 (s, 3 H, C(O)Me), 5.08 (s, 1 H, CH), 6.87-6.91 (m,

1 H, H14), 6.94-6.99 (m, 2 H, H13 + H15), 7.31 (dd, 1 H, H 25,

³J_HH) 6 Hz, ⁴J_HH) 1.8 Hz), 7.45-7.50 (m, 3 H, H16 + H26 +

7.91 (d, 1 H, H25 or H35, J_HH) 6 Hz), 8.52 (d, 1 H, H26 or

3

H36, J_HH) 6 Hz), 8.83 (s, 1 H, H23 or H33), 8.88 (s, 1 H, H23

3

or H33), 9.25 (d, 1 H, H26 or H36, J_HH) 6 Hz), 12.98 (s, 1 H,

NH). ¹³C{¹H} NMR (150 MHz, acetone-d₆, -60 °C): δ 23.7

4

t

H35), 7.93 (d, 1 H, H33, ⁴J_HH) 1.8 Hz), 7.95 (d, 1 H, H23, J_HH

(MeCN), 29.4 (Me, Bu), 29.4 (Me, Bu), 31.5 (C(O)Me), 35.8

) 1.8 Hz), 9.45 (d, 1 H, H36, ³J_HH) 6 Hz), 12.40 (br, 1 H, NH).

¹³C{¹H} NMR (100.81 MHz, CDCl₃): δ 21.2 (MeCN), 29.3

(CMe₃), 35.9 (CMe₃), 51.3 (C2), 116.9 (CH), 121.1 (q, TfO, J_CF

1

) 315 Hz), 121.1 (C23 or C33), 121.2 (C23 or C33), 124.2 (C25

or C35) 124.2 (C25 or C35), 125.4 (CH), 129.1 (CH), 137.8 (CH),

143.0 (C11 or C12), 148.9 (C26 or C36), 148.9 (C11 or C12), 150.3

(C26 or C36), 155.0 (C22 or C32), 155.4 (C22 or C32), 164.6 (C24

or C34), 164,7 (C24 or C34), 185.6 (C1), 195.4 (CO). IR (cm^-1):

1682, 1614. Λ_M(Ω^-1cm²mol^-1): 157. Anal. Calcd for

C₃₀H₃₆F₃N₃O₄PdS: C, 51.62; H, 5.20; N, 6.02; S, 4.59. Found: C,

51.45; H, 5.38; N, 6.08; S, 4.42.

t

(C(O)Me), 30.7 (Me, Bu), 30.8 (Me, Bu), 35.8 (CMe₃), 35.9

(CMe₃), 96.9 (C2), 118.5 (C33) 119.2 (C23), 123.9 (C13 or C15),

124.1 (C25), 124.2 (C35), 125.4 (C13 or C15), 124.4 (C14), 138.3

(C16), 142.8 (C11 or C12), 143.1 (C11 or C12), 149.7 (C26), 153.0

(C36), 154.4 (C22 or C32), 156.6 (C22 or C32), 162.0 (C1), 163.4

(C24 or C34), 163.6 (C24 or C34), 194.7 (CO). IR (cm^-1): ν_CdO

1600. Anal. Calcd for C₂₉H₃₆IN₃OPd: C, 51.53; H, 5.37; N, 6.22.

Found: C, 51.40; H, 5.42; N, 6.09. Crystals of 1 · 0.5Et₂O suitable

for an X-ray diffraction study were obtained by the liquid diffusion

method using Et₂O and n-hexane.

5. Yield: 70.1 mg, 68%. Mp: 168 °C. ¹H NMR (300 MHz,

acetone-d₆): δ 2.15 (s, 3 H, C(O)Me), 2.42 (s, 3 H, Me, tmeda),

2.50-3.23 (various m, 4 H, CH₂, tmeda), 2.58 (s, 3 H, MeCN),

2.86 (s, 3 H, Me, tmeda), 2.87 (s, 3 H, Me, tmeda), 2.89 (s, 3 H,

Me, tmeda), 3.71 (s, 1 H, CH), 6.96-7.16 (m, 4 H, Ar), 12.32 (br,

1 H, NH). ¹³C{¹H} NMR (75 MHz, acetone-d₆) δ 24.4 (MeCN),

31.9 (C(O)Me), 47.4 (Me, tmeda), 48.3 (Me, tmeda), 49.7 (Me,

tmeda), 50.3 (Me, tmeda), 52.1 (C2), 60.5 (CH₂, tmeda), 62.4 (CH₂,

tmeda), 117.7 (CH), 125.7 (CH), 129.3 (CH), 135.9 (CH), 144.1

(C), 144.7 (C), 184.7 (C1), 196.2 (CO). IR (cm^-1): ν_CdO, ν_CdC

1674, 1622. Λ_M(Ω^-1cm²mol^-1): 145. Anal. Calcd for

C₁₈H₂₈F₃N₃O₄PdS: C, 39.60; H, 5.17; N, 7.70; S, 5.87. Found: C,

39.60; H, 5.27; N, 7.93; S, 5.63. Crystals of 5 suitable for an X-ray

diffraction study were obtained from acetone-d₆and Et₂O by the

liquid diffusion method.

1

2. Yield: 136 mg, 67%. Mp: 182 °C, dec. H NMR (200 MHz,

CDCl₃): δ 2.00 (s, 3 H, MeCN), 2.10 (s, 3 H, C(O)Me), 2.45 (s, 3

H, Me, tmeda), 2.50-3.50 (various m, 4 H, CH₂, tmeda), 2.57 (s,

3 H, Me, tmeda), 2.67 (s, 6 H, Me, tmeda), 5.21 (s, 1 H, CH),

6.77-6.90 (m, 3 H, Ar), 7.16-7.24 (m, 1 H, Ar), 13.07 (br, 1 H,

NH). ¹³C{¹H} NMR (100.81 MHz, CDCl₃): δ 20.4 (MeCN), 29.1

(C(O)Me), 48.5 (Me, tmeda), 48.6 (Me, tmeda), 50.5 (Me, tmeda),

50.6 (Me, tmeda), 58.6 (CH₂, tmeda), 62.0 (CH₂, tmeda), 96.7 (C2),

123.0 (CH, Ar), 124.1 (CH, Ar), 124.4 (CH, Ar), 136.8 (CH, Ar),

140.2 (C11 or C12, Ar), 142.3 (C11 or C12, Ar), 162.1 (C1), 194.2

(CO). IR (cm^-1): ν_CdO1600. Anal. Calcd for C₁₇H₂₈IN₃OPd: C,

38.99; H, 5.39; N, 8.02. Found: C, 38.90; H, 5.24; N, 8.05.

t

Synthesis of trans-[PdI(Ar)(PPh₃)₂] (3). To a suspension of 1

(200.0 mg, 0.296 mmol) in Et₂O (20 mL) was added PPh₃(170.8

mg, 0.65 mmol), and the reaction mixture was stirred at room

temperature for 30 min. The resulting suspension was ﬁltered, and

the solid was washed with Et₂O (5 mL), recrystallized from CH₂Cl₂/

Et₂O, and air-dried to give 3 as a pale yellow solid. Yield: 232

mg, 84%. Mp: 188 °C (dec). ¹H NMR (300 MHz, CDCl₃): δ 1.03

(s, 3 H, MeCN), 2.21 (s, 3 H, C(O)Me), 4.83 (s, 1 H, CH), 6.05 (d,

Synthesis of [Pd(Ar)(N^N)(L)] [N^N ) Bubpy, L ) PPh₃

t

(6), N^N ) tmeda, L ) PPh₃(7), BuNC (8)]. To a solution of

4 (mg/mmol for 6: 75/0.11) or 5 (mg/mmol for 7: 155/0.28, for 8:

200/0.37) in acetone (20 mL) was added the appropriate ligand

(L/mg/mmol for 6: PPh₃/31/0.12, for 7: PPh₃/82/0.32, for 8: (L/

µL/mmol): ^tBuNC/41.4/0.37). After 1 (6, 7) or 2.5 (8) h of stirring,

the reaction mixture was ﬁltered through a short pad of Celite, the

solution was concentrated under vacuum to ca. 1 mL, and Et₂O

(20 mL) was added. An oily material formed that was converted

into a solid upon stirring for 30 min with Et₂O (6: 30 mL in an

ice/water bath, 7: 30 mL at room temperature, 8: 5 × 5 mL in an

ice/water bath). The suspension was ﬁltered, and the solid was

washed with Et₂O (3 × 3 mL) and suction dried (8 was additionally

dried in an oven at 80 °C for 4 h) to give the desired compound as

a very pale yellow (6, 7) or yellow (8 · 1.5H₂O) solid.

3

1 H, Ar, J_HH) 8 Hz), 6.38 (t, 1 H, Ar, J_HH) 8 Hz), 6.52 (t, 1

H, Ar, ³J_HH) 8 Hz), 7.16-7.32 (m, 19 H, PPh₃+ Ar), 7.54-7.59

(m, 12 H, PPh₃), 12.67 (1 H, NH). ¹³C{¹H} NMR (75 MHz,

CDCl₃): δ 20.4 (MeCN), 29.4 (C(O)Me), 96.9 (C2), 121.9 (CH,

Ar), 122.9 (CH, Ar), 123.2 (CH, Ar), 127.6 (vt, meta-C, PPh₃, N

) 10.6 Hz), 129,6 (para-C, PPh₃), 131.9 (vt, ipso-C, PPh₃, N )

47 Hz), 135,1 (vt, ortho-C, PPh₃, N ) 12 Hz), 135.7 (vt, CH, Ar,

The First 1,2-Dihydroquinazoline-4-yl Complexes

Organometallics, Vol. 27, No. 13, 2008 3257

6. Yield: 101 mg, 98%. Mp: 157 °C. ¹H NMR (300 MHz,

ν_Ct2152. Anal. Calcd for C₃₆H₃₆I₂N₄Pd₂: C, 43.62; H, 3.64; N,

5.68. Found: C, 43.64; H, 3.53; N, 5.92.

N

t

CDCl₃): δ 1.34 (s, 3 H, MeCN), 1.38 (s, 9 H, Bu), 1.41 (s, 9 H,

^tBu), 2.04 (s, 3 H, C(O)Me), 4.99 (s, 1 H, CH), 6.70 (m, 1 H, Ar),

6.84 (m, 1 H, Ar), 6.95-7.02 (m 2 H, Ar), 7.15 (m, 1 H, Ar), 7.23

(m, 1 H, Ar), 7.30-7.36 (m, 7 H, Ar), 7.43-7.56 (m, 10 H, Ar),

8.27 (m, 2 H, Ar), 13.08 (br, 1 H, NH). ¹³C{¹H} NMR (100 MHz,

Synthesis of trans-[PdI₂{C(dNH^tBu)Ar}(CN^tBu)] (10). To a

suspension of Pd(dba)₂(250 mg, 0.43 mmol) in toluene (10 mL)

were successively added ^tBuNC (98 µL, 0.87 mmol) and IAr (130.9

mg, 0.43 mmol) under nitrogen with a 10 min interval. After 2.5 h

of stirring, the resulting suspension was ﬁltered, and the brown

solid was washed with toluene (3 × 3 mL) and stirred with CH₂Cl₂

(10 mL). The suspension was ﬁltered through a short pad of Celite,

the solution was concentrated to ca. 1 mL, and Et₂O (15 mL) was

added to precipitate a yellow solid that was recrystallized from

CH₂Cl₂and Et₂O and suction dried. Yield: 84.7 mg, 28%. Mp:

t

CDCl₃): δ 20.1 (Me), 29.2 (Me), 30.1 (Me, Bu), 30.2 (Me, Bu),

35.7 (CMe₃), 35.8 (CMe₃), 98.1 (C2), 120.3 (CH, Ar), 120.5 (CH,

Ar), 123.4 (CH, Ar), 124.0 (CH, Ar), 124.3 (CH, Ar), 124.5 (CH,

Ar), 125.4 (CH, Ar), 128.7 (d, ipso-C, PPh₃, J_CP) 53 Hz), 129.0

(d, meta-C, PPh₃, ³J_CP) 11 Hz), 131.8 (d, para-C, PPh₃, ⁴J_CP) 2

2

3

Hz), 134.7 (d, ortho-C, PPh₃, J_CP) 12 Hz), 135.3 (d, C16, J_CP

1

t

3

2

184 °C (dec). H NMR (300 MHz, CDCl₃): δ 1.49 (s, 9 H, Bu),

) 3 Hz), 140.8 (d, C12, J_CP) 2 Hz), 148.0 (d, C11, J_CP) 13

Hz), 149.3 (C26), 159.3 (C36), 155.5 (C22 or C32), 155.6 (C22 or

C32), 159.0 (C1), 165.4 (C24 or C34), 165.6 (C24 or C34), 195.4

1.62 (s, 3 H, Me), 1.81 (s, 9 H, ^tBu), 1.95 (s, 3 H, Me), 4.99 (s, 1

3

H, CH), 6.89 (d, 1 H, Ar, J_HH) 7 Hz), 7.29-7.37 (m, 2 H, Ar),

3

4

(CO). ³¹P{¹H} NMR (81 MHz, CDCl₃): δ 33.0. IR (cm^-1): ν_CdO

,

8.83 (dd, 1 H, Ar, J_HH) 8 Hz, J_HH) 2 Hz), 11.04 (br, 1 H,

NH^tBu), 11.94 (br, 1 H, NHAr). ¹³C{¹H} NMR (75 MHz, CDCl₃):

ν

_CdC, ν_CdN, 1614, 1556. Λ_M(Ω^-1cm²mol^-1): 152. Anal. Calcd

t

δ 22.0 (MeCN), 28.1 (C(O)Me), 30.0 (Me, Bu), 30.1 (Me, Bu),

61.0 (CMe₃), 98.5 (C2), 126.9 (CH, Ar), 128.6 (CH, Ar), 130.0

(CH, Ar), 131.5 (C), 137.2 (CH, Ar), 139.2 (C), 163.4 (C1), 196.1

(CO). IR (cm^-1): ν_{Ct N}2202, ν_CdO, ν_CdN1600, 1590. Anal. Calcd

for C₂₁H₃₁I₂N₃OPd: C, 35.94; H, 4.45; N, 5.99. Found: C, 36.06;

H, 4.33; N, 5.97. Crystals of 10 suitable for an X-ray diffraction

study were obtained by the liquid diffusion method using CH₂Cl₂

and Et₂O.

for C₄₈H₅₁F₃N₃O₄PPdS: C, 60.03; H, 5.35; N, 4.37; S, 3.34. Found:

C, 59.99; H, 5.68; N, 4.04; S, 3.17.

7. Yield: 211 mg, 92%. Mp: 182 °C (dec). ¹H NMR (300 MHz,

CDCl₃): δ 1.35 (s, 3 H, MeCN), 1.90 (s, 3 H, Me, tmeda), 2.18 (s,

3 H, Me, tmeda), 2.24 (s, 3 H, C(O)Me), 2.29 (m, 1 H, CH₂, tmeda),

3

2.32 (d, 3 H, Me, tmeda, J_HP) 2 Hz), 2.56-2.61 (m, 1 H, CH₂,

tmeda), 2.77 (d, 3 H, Me, tmeda, ³J_HP) 2 Hz), 3.28 (m, 1 H, CH₂,

tmeda), 3.73 (m, 1 H, CH₂, tmeda), 5.20 (s, 1 H, CH), 6.51 (m, 1

H, Ar), 6.84 (m, 2 H, Ar), 7.30-7.47 (m, 16 H, PPh₃+ Ar), 7.57

(m, 1 H, Ar), 13.69 (br, 1 H, NH). ³¹C{¹H} NMR (75 MHz,

CDCl₃): δ 19.8 (MeCN), 29.4 (C(O)Me), 47.6 (Me, tmeda), 50.6

(Me, tmeda), 51.7 (Me, tmeda), 61.1 (CH₂, tmeda), 61.9 (CH₂,

tmeda), 97.8 (C2), 122.0 (C13 or C15), 121.0 (q, TfO, ¹J_CF) 320

Hz), 123.7 (C13 or C15), 125.1 (C14), 128.4 (d, ipso-C, PPh₃, ¹J_CP

) 51 Hz),128.8 (d, meta-CH, PPh₃, ³J_CP) 11 Hz), 131.2 (d, para-

CH, PPh₃, ⁴J_CP) 3 Hz), 134.6 (d, ortho-CH, PPh₃, ²J_CP) 11 Hz),

t

Synthesis of trans-[PdI{C(dNR)Ar}(CNR)₂] [R ) Bu (11),

Xy (12)]. To a solution of 1 (mg/mmol for 11: 220/0.32, for 12:

132/0.19) in CH₂Cl₂(20 mL) was added the appropriate RNC (R/

mL/mmol for 11: ^tBu/0.18/1.59, R/mg/mmol for 12: Xy/128.1/0.98).

After 1 h of stirring, the solution was concentrated under vacuum

(1 mL). Upon addition of n-pentane (11, 20 mL) or Et₂O (12, 20

mL), a yellow suspension formed. In the case of 11, the suspension

was stirred in an ice/water bath for 10 min and ﬁltered. The yellow

solid was washed with Et₂O (2 × 1 mL), recrystallized from

CH₂Cl₂/n-pentane, and suction dried. For 12 the suspension was

ﬁltered and the solid recrystallized from CH₂Cl₂/Et₂O and suction

dried to give 12 as a yellow solid.

3

136.2 (d, C16, J_CP) 3 Hz), 141.4 (d, C12, J_CP) 3 Hz), 145.4

(d, C11, J_CP) 13 Hz), 159.1 (C1), 195.2 (CO). ³¹P{¹H} NMR

2

(121 MHz, CDCl₃): δ 26.8. IR (cm^-1): ν_CdO, ν_CdC1602, 1556.

Λ_M(Ω^-1cm²mol^-1): 153. Anal. Calcd for C₃₆H₄₃F₃N₃O₄PPdS:

C, 53.50; H, 3.36; N, 5.20; S, 3.97. Found: C, 53.57; H, 5.72; N,

5.05; S, 3.76. Crystals of 7 · 2CH₂Cl₂were obtained from CH₂Cl₂

and Et₂O by the liquid diffusion method.

11. Yield: 180 mg, 86%. Mp: 135 °C. ¹H NMR (300 MHz,

t

CDCl₃): δ 1.48 (s, 18 H, Bu), 1.56 (s, 9 H, Bu), 1.93 (s, 3 H,

MeCN), 2.04 (s, 3 H, C(O)Me), 5.14 (s, 1H, CH), 7.02-7.04 (m,

1 H, Ar), 7.18-7.25 (m, 2 H, Ar), 7.46-7.51 (m, 1 H, Ar), 11.96

(br, 1 H, NH). ¹³C{¹H} NMR (300 MHz, CDCl₃): δ 20.6 (CNMe),

29.2 (MeC(O)), 29.6 (Me, ^tBu), 30.7 (Me, ^tBu), 57.9 (CMe₃), 58.1

(CMe₃), 97.8 (C2), 125.3 (CH, Ar), 127.1 (CH, Ar), 127.2 (CH,

Ar), 130.3 (CH, Ar), 132.8 (C), 139.2 (C), 159.6 (C1), 166.6

8 · 1.5H₂O. Yield: 168 mg, 70%. Mp: 55 °C. ¹H NMR (400 MHz,

t

CDCl₃): δ 1.36 (s, 9 H, Bu), 1.56 (br, 3 H, H₂O), 2.05 (s, 3 H,

Me), 2.11 (s, 3 H, Me), 2.39 (s, 3 H, Me, tmeda), 2.63 (s, 3 H, Me,

tmeda), 2.79 (s, 3 H, Me, tmeda), 2.86 (s, 3 H, Me, tmeda),

2.58-3.10 (various m, 4 H, CH₂, tmeda), 5.21 (s, 1 H, CH),

6.92-7.01 (m, 2H, Ar), 7.05-7.10 (m, 1 H, Ar), 7.40 (dd, 1 H,

(CdN^tBu), 194.6 (CO). IR (cm^-1): ν_Ct

2192, ν_CdO, ν_CdN

N

1640-1574 br. Anal. Calcd for C₂₆H₃₉IN₄OPd: C, 47.54; H, 5.98;

N, 8.53. Found: C, 47.51; H, 5.99; N, 8.69.

3

4

Ar, J_HH) 7 Hz, J_HH) 2 Hz), 13.27 (br, 1 H, NH). ³¹C{¹H}

NMR (100 MHz, CDCl₃): δ 20.0 (Me), 29.3 (Me), 29.8 (Me, ^tBu),

48.7 (Me, tmeda), 49.6 (Me, tmeda), 50.1, (Me, tmeda), 51.0 (Me,

tmeda), 59.0 (CH₂, tmeda), 59.3 (CMe₃), 62.6 (CH₂, tmeda), 97.5

(C2), 120.7 (q, TfO, ¹J_CF) 320 Hz), 123.0 (CH, Ar), 125.1 (CH,

Ar), 125.2 (CH, Ar), 135.8 (CH, Ar), 140.1 (C), 141.5 (C), 159.2

(C1), 195.6 (CO). IR (cm^-1): ν_NH, 3508, ν_CdO, ν_CdC1601, 1567,

1557. Λ_M(Ω^-1cm²mol^-1): 156. Anal. Calcd for

C₂₃H₄₀F₃N₄O_5.5PdS: C, 42.11; H, 6.15; N, 8.54; S, 4.89. Found: C,

41.94; H, 6.03; N, 8.34; S, 5.07.

12. Yield: 138 mg, 91%. Mp: 162 °C (dec). ¹H NMR (400 MHz,

CDCl₃): δ 1.93 (s, 3 H, MeCN), 1.95 (s, 3 H, C(O)Me), 2.16 (s, 6

H, Me, Xy), 2.23 (s, 12 H, Me, Xy) 5.19 (s, 1H, CH), 6.80-6.85

(m, 3 H), 6.99-7.07 (m, 4 H), 7.12-7.14 (m, 1 H), 7.18-7.24

3

4

(m, 2 H), 7.29-7.35 (m, 2 H), 8.11 (dd, 1 H, J_HH) 8 Hz, J_HH

) 2 Hz), 12.64 (br, 1 H, NH). ¹³C{¹H} NMR (75 MHz, CDCl₃):

δ 18.8 (Me, Xy), 19.0 (Me, Xy), 20.1 (MeCN), 29.1 (C(O)Me),

98.7 (C2), 123.3 (CH, Ar), 125.6 (CH, Ar), 126.9 (C), 127.1 (CH,

Ar), 127.8 (CH, Ar), 127.9 (CH, Ar), 128.8 (CH, Ar), 129.9 (CH,

Ar), 131.2 (CH, Ar), 135.1 (C), 135.7 (C), 135.8 (C), 141.1 (C),

150.0 (C), 155.2 (C), 159.1 (C1), 174.2 (CdNXy), 195.6 (CO). IR

Synthesis of [Pd₂I₂(CNXy)₄] (9). A suspension of Pd(dba)₂(250

mg, 0.43 mmol), XyNC (114.1 mg, 0.87 mmol), and IAr (130.9

mg, 0.43 mmol) in toluene was stirred under a nitrogen atmosphere

for 4.5 h. The solvent was removed under vacuum, the residue was

stirred with CH₂Cl₂(10 mL), and the suspension was ﬁltered. The

solution was concentrated to dryness, and the residue was stirred

with Et₂O (5 mL) in an ice/water bath. The orange solid was ﬁltered,

washed with Et₂O (3 × 3 mL), and suction dried. Yield: 16%. Mp:

(cm^-1): ν_Ct2181 s, ν_CdO, ν_CdN1620-1556 br. Anal. Calcd for

N

C₃₈H₃₉IN₄OPd: C, 56.98; H, 4.91; N, 6.99. Found: C, 57.01; H,

5.16; N, 7.08.

Synthesis of [Pd{µ-N,C,N′,O-N(Xy){dCC₆H₄{NC(Me)CHC-

(Me)O}-2}}]₂(13). To a solution of 5 (200 mg, 0.37 mmol) in

acetone (20 mL) was added XyNC (48 mg, 0.37 mmol). After 2.5 h

of stirring, the solution was ﬁltered, and the solvent removed under

vacuum to dryness. The residue was stirred with MeOH (20 mL)

1

217 °C. H NMR (300 MHz, CDCl₃): δ 2.53 (s, 6 H, Me, Xy),

7.10, 7.22 (AB₂system, 3 H, CH, Xy, J_AB) 9 Hz). IR (cm^-1):

3258 Organometallics, Vol. 27, No. 13, 2008

Vicente et al.

4

1

at 0 °C for 15 min, the suspension was ﬁltered, and the solid was

suction dried and then in an oven at 80 °C for 4 h to give 13 as an

orange solid. Yield: 98 mg, 63%. Mp: 242 °C (dec). ¹H NMR (300

MHz, CDCl₃): δ 1.70 (s, 3 H, C(O)Me), 1.97 (s, 3 H, Me, Xy),

2.12 (s, 3 H, MeCN), 2.69 (s, 3 H, Me, Xy), 4.92 (s, 1 H, CH),

5.96 (dd, 1 H, Ar, J_HH) 8 Hz, J_HH) 1 Hz), 6.26 (t, 1 H, Ar,

³J_HH) 8 Hz), 6.74-7.07 (various m, 5 H, Ar). ¹³C{¹H} NMR (75

MHz, CDCl₃): δ 18.7 (Me, Xy), 19.0 (Me, Xy), 22.4 (MeCN), 26.1

(C(O)Me), 104.7 (C2), 120.1 (CH, Ar), 121.6 (CH, Ar), 123.6 (CH,

Ar), 125.2 (CH, Ar), 127.8 (CH, Ar), 128.0 (CH, Ar), 129.4 (CH,

Ar), 130.1 (C), 131.0 (C), 140.0 (C), 147.8 (C), 155.8 (C), 161.8

(C1), 183.4 (CdNXy), 207.8 (CO). IR (cm^-1): ν_CdO, ν_CdN1565,

1563, 1550. Anal. Calcd for C₄₀H₄₀N₄O₂Pd₂: C, 58.48; H, 4.91; N,

6.82. Found: C, 58.76; H, 5.14; N, 6.69. (FAB⁺): (m/z, %) 820

(M⁺, 100) 410 (M⁺/2, 93). Crystals of 13 suitable for an X-ray

diffraction study were obtained from CH₂Cl₂/MeOH by the liquid

diffusion method.

CH, PPh₃, J_CP) 2 Hz), 131.8 (d, ipso-C, PPh₃, J_CP) 46 Hz),

2

134.9 (d, ortho-CH, PPh₃, J_CP) 12 Hz), 140.2 (C), 150.5 (d, C,

J_CP) 8 Hz), 153.8 (C), 162.8 (C1), 179.0 (d, C ) NXy, ²J_CP) 5

Hz), 182.3 (CO). ³¹P{¹H} (121 MHz, CDCl₃): δ 31.15. IR (cm^-1):

ν

_CdO, ν_CdN, ν_CdC1611, 1589, 1557, 1415. Anal. Calcd for

C₃₈H₃₅N₂OPPd: C, 67.81; H, 5.24; N, 4.16. Found: C, 67.41; H,

5.63; N, 4.03.

3

4

1

16a · H₂O. Yield: 136.8 mg, 60%. Mp: 197 °C (dec). H NMR

(200 MHz, CDCl₃): δ 1.22 (s, 9 H, ^tBu), 1.57 (br, 2 H, H₂O), 1.95

(s, 3 H, C(O)Me), 2.17 (s, 6 H, Me, Xy), 2.33 (s, 3 H, MeCN),

5.01 (s, 1 H, CH), 6.85-6.99 (m, 4 H, Ar), 7.09-7.21 (m, 2 H,

Ar), 7.98 (dd, 1 H, Ar, ³J_HH) 8 Hz, ⁴J_HH) 1 Hz). ¹³C{¹H} NMR

(75 MHz, CDCl₃): δ 19.4 (Me, Xy), 24.3 (MeCN), 27.4 (C(O)Me),

29.9 (CMe₃), 56.6 (CMe₃), 102.8 (C2), 120.4 (CH, Ar), 122.3 (CH,

Ar), 123.0 (CH, Ar), 125.2 (CH, Ar), 126.9 (ortho-C, Xy), 127.6

(meta-CH, Xy), 129.8 (CH, Ar), 142.3 (C), 152.9 (ipso-C, Xy),

154.8 (C), 163.2 (C1), 178.4 (CdNXy), 182.8 (CO). IR (cm^-1):

ν_Ct2199, ν_CdO, ν_CdN, ν_CdC1628, 1583, 1562. Anal. Calcd for

C₂₅H₃₁N₃O₂Pd: C, 58.65; H, 6.10; N, 8.21. Found: C, 58.82; H,

6.25; N, 8.17.

Synthesis of [Pd{µ-N,C,N′,O-N(Xy){dCC₆H₄{NdC(Me)-

CH₂C(O)Me}-2}}]₂(TfO)₂(14a). To a solution of 13 (150 mg, 0.17

mmol) in CH₂Cl₂(7 mL) was added an excess of HTfO (0.1 mL,

1.13 mmol). After 1.5 h of stirring, the solution was concentrated

under vacuum to dryness. The residue was stirred with Et₂O (5

mL), and the suspension was ﬁltered. The solid was washed with

Et₂O (3 × 3 mL), suction dried, and heated in an oven at 80 °C for

4 h to give 14a · 2H₂O as a pale yellow solid. Yield: 192.5 mg,

N

Synthesis of [Pd{C,N,O-C(dN^tBu)C₆H₄{NC(Me)CHC(Me)O}-

2}(CN^tBu)] (16b). To a solution of 21 (60 mg, 0.11 mmol) in

acetone (20 mL) was added Na₂CO₃(7 mg, 0.07 mmol). The

resulting suspension was stirred at room temperature for 5 h and

then concentrated to dryness under vacuum. The residue was stirred

with Et₂O (2 × 10 mL), and the suspension was ﬁltered. The

solution was concentrated under vacuum to dryness to give 16b as

1

99%. Mp: 181 °C (dec). H NMR (300 MHz, acetone-d₆): δ 1.81

(s, 3 H, Me, Xy), 2.36 (s, 3 H, C(O)Me), 2.65 (s, 3 H, MeCN),

2.74 (s, 3 H, Me, Xy), 3.35 (br, 4 H, H₂O), 4.79, 5.11 (AB system,

2 H, CH₂, J_AB) 20 Hz), 6.43 (d, 1 H, Ar, ³J_HH) 8 Hz), 6.95-7.00

1

a yellow solid. Yield: 49 mg, 100%. Mp: 206 °C. H NMR (400

t

MHz, CDCl₃): δ 1.47 (s, 9 H, Bu), 1.53 (s, 9 H, Bu), 1.98 (s, 3

H, C(O)Me), 2.18 (s, 3 H, MeCN), 4.96 (s, 1 H, CH), 6.73 (t, 1 H,

3

(m, 2 H, Ar), 7.13-7.26 (m, 2 H, Ar), 7.42 (t, 1 H, Ar, J_HH) 8

Hz), 7.55 (m, 1 H, Ar). ¹³C{¹H} NMR (75 MHz, acetone-d₆): δ

18.4 (Me, Xy), 19.0 (Me, Xy), 24.8 (MeCN), 31.5 (C(O)Me), 56.7

(CH₂), 123.4 (CH, Ar), 124.6 (CH, Ar), 128.1 (CH, Ar), 129.1 (CH,

Ar), 129.5 (CH, Ar), 129.8 (CH, Ar), 130.3 (C), 131.9 (C), 132.4

(CH, Ar), 141.7 (C), 146.5 (C), 151.8 (C), 178.3 (C1) 200.5

(CdNXy), 209.9 (CO). IR (cm^-1): ν_CdO, ν_{Ct N}1672, 1592, 1578,

1557. Λ_M(Ω^-1cm²mol^-1): 264.9. Anal. Calcd for

C₄₂H₄₆F₆N₄O₁₀Pd₂S₂: C, 43.57; H, 4.00; N, 4.84; S, 5.54. Found:

C, 43.69; H, 3.86; N, 4.98; S, 5.11. Crystals of 14a · Et₂O · Me₂CO

and 14b suitable for X-ray diffraction studies were obtained from

acetone and Et₂O by the liquid diffusion method.

3

³J_HH) 7 Hz), 6.86 (d, 2 H, J_HH) 8 Hz), 7.02 (t, 1 H, J_HH) 7

Hz), 7.49 (d, 1 H, ³J_HH) 8 Hz). ¹³C{¹H} NMR (50 MHz, CDCl₃):

t

δ 22.8 (MeCN), 27.3 (C(O)Me), 30.0 (Me, Bu), 31.1 (Me, Bu),

54.9 (CMe₃), 102.8 (C2), 119.2 (CH, Ar), 122.9 (CH, Ar), 124.9

(CH, Ar), 128.6 (CH, Ar), 146.3 (C), 152.4 (C), 162.9 (C1), 167.7

(CdN^tBu), 182.1 (CO). IR (cm^-1): ν_Ct2186, ν_CdO, ν_CdN, ν_CdC

N

1615, 1579-1541 (br). Anal. Calcd for C₂₁H₂₉N₃OPd: C, 56.57;

H, 6.56; N, 9.42. Found: C, 56.20; H,6.80; N, 9.39.

Synthesis of [Pd{C,N,O-C(dNXy)C₆H₄{NC(Me)CHC(Me)O}-

2}(CNXy)] (17). To a solution of 2 (120 mg, 0.22 mmol) in CH₂Cl₂

(20 mL) was added XyNC (57.1 mg, 0.44 mmol). After 15 h of

stirring, the solution was concentrated under vacuum to dryness.

The residue was stirred with n-hexane (20 mL), and the white

suspension was ﬁltered to remove (H₂tmeda)I₂. The ﬁltrate was

concentrated under vacuum to dryness, and the residue was stirred

with n-hexane (2 × 1.5 mL) at -30 °C. The suspension was ﬁltered,

and the solid was suction dried to give 17 as an orange solid. Yield:

Synthesis of [Pd{C,N,O-C(dNXy)C₆H₄{NC(Me)CHC(Me)O}-

t

2}(L)] [L ) PPh₃(15), BuNC (16a)]. To a solution of 13 (mg/

mmol for 15: 90/0.10, for 16a: 200/0.23) in degassed CHCl₃(20

mL) was added the appropriate ligand (L/mg/mmol for 15: PPh₃/

55/0.21; L/µL/mmol for 16a: ^tBuNC/65/0.58). The resulting solution

was reﬂuxed under nitrogen atmosphere (15, 10.5 h) or heated in

a Carius tube (16a, at 65 °C, 9 h), and then the solvent was removed

under vacuum. For 15, the oily residue was stirred with n-pentane

(3 × 2 mL) at 0 °C until a solid formed that was ﬁltered off, suction

dried, and then heated in an oven at 80 °C for 4 h to give 15. In

the case of 16a the residue was dissolved in Et₂O (20 mL), the

solution was ﬁltered through a short pad of Celite, the ﬁltrate was

concentrated under vacuum to dryness, and the residue was stirred

with n-pentane (2 mL) at 0 °C for 15 min. The suspension was

ﬁltered and the yellow solid collected and washed with n-pentane

(2 × 2 mL) and suction dried to give 16a · H₂O, which could not

be dehydrated even after heating in an oven at 80 °C for 4 h.

1

104.2 mg, 84%. Mp: 190 °C (dec). H NMR (400 MHz, CDCl₃):

δ 1.95 (s, 3 H, C(O)Me), 2.21 (s, 6 H, Me, Xy), 2.22 (s, 6 H, Me,

Xy), 2.35 (s, 3 H, MeCN), 5.04 (s, 1 H, CH), 6.26 (t, 1 H, ³J_HH

)

8 Hz), 6.72 (d, 2 H, ³J_HH) 8 Hz), 6.92 (t, 1 H, ³J_HH) 7 Hz), 6.98

(d, 2 H, ³J_HH) 8 Hz), 7.13 (m, 2 H), 7.20 (td, 1 H, ³J_HH) 8 Hz,

⁴J_HH) 2 Hz), 8.02 (dd, 1 H, ³J_HH) 8 Hz, ⁴J_HH) 1.5 Hz). ¹³C{¹H}

NMR (50 MHz, CDCl₃): δ 18.5 (Me, Xy), 19.4 (Me, Xy), 24.2

(MeCN), 27.3 (C(O)Me), 103.0 (C2), 120.5 (CH, Ar), 122.8 (CH,

Ar), 123.2 (CH, Ar), 125.3 (CH, Ar), 126.7 (ipso-C, Xy), 127.3

(meta-CH, Xy), 127.3 (meta-CH, Xy), 128.7 (CH, Ar), 129.9 (CH,

Ar), 134.4 (ipso-C, Xy), 141.9 (C), 153.0 (C), 154.8 (C), 163.3

(C1), 178.2 (CdNXy), 182.9 (CO). IR (cm^-1): ν_Ct2170, ν_CdO

,

15. Yield: 82 mg, 58%. Mp: 199 °C. ¹H NMR (400 MHz,

CDCl₃): δ 1.46 (s, 6 H, Me, Xy), 1.76 (s, 3 H, C(O)Me), 2.27 (s,

N

ν_CdN, ν_CdC1633, 1556, 1520. Anal. Calcd for C₂₉H₂₉N₃OPd: C,

3

64.27; H, 5.39; N, 7.75. Found: C, 63.92; H, 5.47; N, 7.67. Crystals

of 17 suitable for an X-ray diffraction study grew upon cooling a

solution of the crude product in a mixture of Et₂O/n-hexane (1:1)

at 4 °C.

3 H, MeCN), 5.01 (s, 1 H, CH), 6.41 (d, 2 H, J_HH) 4 Hz), 6.61

(m, 1 H), 6.71 (s, 1 H), 6.72 (s, 1 H), 6.98 (m, 2 H), 7.28-7.38

(m, 9 H), 7.71 (m, 6 H). ¹³C{¹H} (75 MHz, CDCl₃): δ 18.1 (Me,

4

Xy), 23.3 (d, MeCN, J_CP) 5 Hz), 26.9 (C(O)Me), 103.3 (C2),

4

120.7 (d, CH, Ar, J_CP) 3 Hz), 120.8 (CH, Ar), 122.0 (CH, Ar),

Synthesisof[Pd{C,N,O-C(dNHXy)C₆H₄{NdC(Me)CH₂C(O)Me}-

2}(PPh₃)](TfO)₂(18). To a solution of 15 (60 mg, 0.09 mmol) in

CH₂Cl₂(5 mL) was added HTfO (0.1 mL, 1.13 mmol). After 3 h

124.6 (CH, Ar), 124.7 (CMe, Xy), 127.3 (meta-CH, Xy), 127.8 (d,

3

meta-CH, PPh₃, J_CP) 10 Hz), 128.6 (CH, Ar), 129.9 (d, para-

The First 1,2-Dihydroquinazoline-4-yl Complexes

Organometallics, Vol. 27, No. 13, 2008 3259

of stirring, the solution was concentrated under vacuum to dryness.

The residue was washed with Et₂O (3 × 5 mL, at 0 °C),

recrystallized with CH₂Cl₂and n-pentane at 0 °C, ﬁltered under

nitrogen, and dried by suction for 4 h to give 18 · 2H₂O. Yield:

22) and suction dried to give 21 · H₂O or 22 · H₂O. After heating in

an oven at 80 °C for 6 h, 21 decomposed and 22 did not dehydrate.

21 · H₂O. Yield: 29.6 mg, 74%. Mp: 137 °C (dec). ¹H NMR (400

t

MHz, CDCl₃): δ 1.61 (s, 9 H, Bu), 1.64 (s, 3 H, H₂O), 1.81 (s, 9

1

H, ^tBu), 2.04 (s, 3 H, C(O)Me), 2.27 (s, 3 H, MeCN), 5.15 (s, 1 H,

CH), 6.91 (d, 1 H, ³J_HH) 8 Hz), 7.04 (td, 1 H, ³J_HH) 8 Hz, ⁴J_HH

59.1 mg, 65%. Mp: 101 °C. H NMR (400 MHz, CDCl₃): δ 1.73

(s, 6 H, Me, Xy), 2.24 (s, 3 H, C(O)Me), 2.71 (s, 3 H, MeCN),

4.33 (br, 4 H, H₂O), 4.88 (br, 2 H, CH₂), 6.43 (d, 1 H, Ar, ³J_HH

)

3

4

) 1 Hz), 7.33 (td, 1 H, J_HH) 8 Hz, J_HH) 1 Hz), 7.88 (d, 1 H,

3

³J_HH) 8 Hz), 9.73 (br, 1 H, NH). ¹³C{¹H} NMR (75 MHz, CDCl₃):

7 Hz), 6.94-6.98 (m, 3 H, Ar), 7.18 (t, 1 H, J_HH) 7 Hz),

7.56-7.85 (m, 17 H, Ar), 8.98 (br, 1 H, NH). ¹³C{¹H} NMR (100

MHz, CDCl₃): δ 17.9 (Me, Xy), 24.6 (MeCN), 30.9 (C(O)Me),

56.3 (CH₂), 120.42 (q, TfO, ¹J_CF) 317 Hz), 124.6 (CH, Ar), 129.6

t

δ 23.0 (MeCN), 25.8 (C(O)Me), 29.7 (Me, Bu), 30.3 (Me, Bu),

59.7 (CMe₃), 60.1 (CMe₃), 105.4 (C2), 120.1 (CH, Ar), 124.2 (CH,

Ar), 125.1 (CH, Ar), 134.7 (CH, Ar), 140.7 (C), 154.2 (C), 162.9

3

(C1), 181.8 (CdN^tBu), 215.6 (CO). IR (cm^-1): ν_Ct2204. Λ_M

(CH, Ar), 129.7 (CH, Ar), 130.0 (d, meta-CH, PPh₃, J_CP) 11

N

(Ω^-1cm²mol^-1): 163.3. Anal. Calcd for C₂₁H₃₂ClN₃O₆Pd: C,

44.69; H, 5.72; N, 7.45. Found: C, 44.99; H, 5.85; N, 7.65. Crystals

of 21 suitable for an X-ray diffraction study were obtained by the

liquid diffusion method using CH₂Cl₂and Et₂O.

Hz), 130.5 (CH, Ar), 132.7 (CH, Ar), 133.4 (para-CH, PPh₃), 134.9

2

(d, ortho-CH, PPh₃, J_CP) 12 Hz), 136.5 (CH, Ar), 148.3 (C),

153.1 (C), 180.2 (C1), 191.5 (CdNXy), 216.8 (CO). ³¹P{¹H} NMR

(162 MHz, CDCl₃): δ 33.9. IR (cm^-1): ν_CdO, ν_CdN, ν_CdC1660-1515

br. Λ_M(Ω^-1cm²mol^-1): 241.5. Anal. Calcd for

C₄₀H₄₁F₆N₂O₉PPdS₂: C, 47.60; H, 4.09; N, 2.78; S, 6.35. Found:

C, 47.24; H, 3.99; N, 2.70; S, 6.47.

22 · H₂O. Yield: 33 mg, 68%. Mp: 280 °C (dec). ¹H NMR (300

MHz, CDCl₃): δ 1.63 (br, 2 H, H₂O), 1.98 (s, 3 H, C(O)Me), 2.20

(s, 6 H, Me, Xy), 2.38 (s, 3 H, MeCN), 2.50 (s, 6 H, Me, Xy), 5.19

3

Synthesis of [Pd{C,N,O-C(dNHXy)C₆H₄{NC(Me)CHC(O)Me}-

2}(L)]TfO [^tBuNC (19), XyNC (20)]. To a solution of 16a (for

19: 100 mg, 0.20 mmol) or 17 (for 20: 85 mg, 0.16 mmol) in

CH₂Cl₂(5 mL) was added HTfO (0.1 mL, 1.13 mmol). After 1

(19) or 3 h (20) of stirring, the solution was concentrated under

vacuum to dryness.The residue was stirred with Et₂O (2 mL) at 0

°C for 15 min, and the resulting suspension was ﬁltered. The solid

collected was washed with Et₂O (3 × 3 mL) and suction dried to

give an orange solid. Additionally, 19 was heated in an oven at 80

°C for 4 h.

(s, 1 H, CH), 6.63 (t, 1 H, J_HH) 8 Hz), 6.89 (d, 2 H, J_HH) 8

3

4

Hz), 7.05-7.30 (m, 5 H), 7.48 (td, 1 H, J_HH) 8 Hz, J_HH) 1

Hz), 8.23 (d, 1 H, J_HH) 8 Hz), 11.78 (br, 1 H, NH). ¹³C{¹H}

3

NMR (300 MHz, CDCl₃): δ 18.4 (Me, Xy), 19.1 (Me, Xy), 24.1

(MeCN), 26.1 (C(O)Me), 105.3 (C2), 121.4 (CH, Ar), 125.5 (CH,

Ar), 125.6 (CH, Ar), 127.9 (CH, Ar), 128.3 (CH, Ar), 129.9 (CH,

Ar), 130.3 (CH, Ar), 134.6 (ortho-C, Xy), 134.7 (ortho-C, Xy),

136.4 (CH, Ar), 140.7 (C), 163.7 (C1), 183.3 (CdNXy), 217.1

(CO). IR (cm^-1): ν_{Ct N}2204 s. Λ_M(Ω^-1cm²mol^-1): 170.5. Anal.

Calcd for C₂₉H₃₂ClN₃O₆Pd: C, 52.74; H, 4.89; N, 6.36. Found: C,

52.79; H, 4.78; N, 6.45. Crystals of 22 · CHCl₃suitable for an X-ray

diffraction study were obtained by the liquid diffusion method using

CHCl₃and Et₂O.

19. Yield: 90.8 mg, 73%. Mp: 192 °C (dec). ¹H NMR (400 MHz,

CDCl₃): δ 1.27 (s, 9 H, ^tBu), 1.98 (s, 3 H, C(O)Me), 2.35 (s, 3 H,

MeCN), 2.45 (s, 6 H, Me, Xy), 5.13 (s, 1 H, CH), 6.99-7.17 (m,

4 H, Ar), 7.26-7.32 (m, 1 H, Ar), 7.42 (t, 1H, ³J_HH) 8 Hz), 8.22

Synthesis of [Pd{C,N,O-C(dNHXy)C₆H₄{NC(Me)CHC(Me)O}-

2}PPh₃]TfO (23). To a solution of 14a (150 mg, 0.13 mmol) in

degassed CHCl₃(20 mL) was added PPh₃(81.6 mg, 0.31 mmol),

and the solution was stirred in a Carius tube at 65 °C for 10 h. The

solution was concentrated under vacuum to ca. 1 mL, and Et₂O

(20 mL) was added. The collected solid was recrystallized from

CH₂Cl₂and Et₂O and dried in an oven a 80 °C for 24 h. Yield:

3

(d, 1 H, J_HH) 8 Hz), 12.23 (s, 1 H, NH). ¹³C{¹H} NMR (75

MHz, CDCl₃): δ 18.9 (Me, Xy), 24.0 (MeCN), 26.3 (C(O)Me),

t

1

29.8 (Me, Bu), 58.5 (CMe₃), 105.0 (C2), 120.3 (q, TfO, J_CF

)

319 Hz), 121.1 (CH), 124.9 (CH), 125.7 (CH), 128.5 (meta-CH,

Xy), 129.4 (CH), 134.7 (C), 135.8 (CH), 136.7 (C), 141.1 (C), 158.0

(C), 163.5 (C1), 183.3 (CdNXy), 216.4 (CO). IR (cm^-1): ν_Ct

N

2212, ν_CdO, ν_CdN, ν_CdC1569, 1544, 1524. Λ_M(Ω^-1cm²mol^-1):

165.3. Anal. Calcd for C₂₆H₃₀F₃N₃O₄PdS: C, 48.49; H, 4.70; N,

6.52; S, 4.98. Found: C, 48.94; H, 4.85; N, 6.61; S, 5.10.

1

124 mg, 58%. Mp: 114 (dec) °C. H NMR (300 MHz, CDCl₃): δ

1.66 (s, 3 H, C(O)Me), 1.79 (s, 6 H, Me, Xy), 2.34 (s, 3H, MeCN),

3

5.18 (s, 1 H, CH), 6.17 (d, 1 H, J_HH) 8 Hz), 6.51 (t, 1 H, J_HH

20. Yield: 86.5 mg, 80%. Mp: 186 °C (dec). ¹H NMR (300 MHz,

CDCl₃): δ 1.98 (s, 3 H, C(O)Me), 2.21 (s, 6 H, Me, Xy), 2.39 (s,

3 H, MeCN), 2.50 (s, 6 H, Me, Xy), 5.18 (s, 1H, CH), 6.63 (t, 1 H,

) 8 Hz), 6.98 (d, 2 H, J_HH) 8 Hz), 7.07 (d, 1 H, J_HH) 8 Hz),

7.16 (t, 1 H, ³J_HH) 8 Hz), 7.33 (t, 1 H, ³J_HH) 8 Hz), 7.53-7.71

(m, 15 H, PPh₃), 9.08 (br, 1 H, NH). ¹³C{¹H} (50 MHz, CDCl₃):

3

4

³J_HH) 8 Hz), 6.88 (d, 2 H, J_HH) 7 Hz), 7.06-7.11 (m, 4 H),

δ 18.1 (Me, Xy), 23.4 (d, MeCN, J_CP) 6 Hz), 25.8 (C(O)Me),

3

7.22-7.27 (m, 1 H), 7.46 (m, 1 H), 8.27 (d, 1 H, J_HH) 7 Hz),

106.1 (C2), 121.9 (d, CH, Ar, ⁴J_CP) 3 Hz), 123.4 (CH, Ar), 125.2

12.4 (br, 1 H, NH). ¹³C{¹H} NMR (75 MHz, CDCl₃): δ 18.4 (Me,

Xy), 19.0 (Me, Xy), 24.0 (MeCN), 26.1 (C(O)Me), 105.3 (C2),

(CH, Ar), 126.3 (d, ipso-C, PPh₃, ¹J_CP) 50 Hz), 129.4 (CH, Ar),

3

129.5 (d, meta-CH, PPh₃, J_CP) 11 Hz), 129.9 (CH, Ar), 132.2

1

120.3 (q, TfO, J_CF) 319 Hz), 121.3 (CH), 125.2 (CH), 126.0

(CMe, Xy), 132.6 (d, para-CH, PPh₃, ⁴J_CP) 3 Hz), 134.8 (d, ortho-

CH, PPh₃, ²J_CP) 12 Hz), 136.1 (CH, Ar), 136.7 (C), 137.5 (d, C,

J_CP) 1 Hz), 158.4 (C), 164.1 (C1), 182.9 (CdNXy), 223.0 (d,

CO, ³J_CP) 8 Hz). ³¹P{¹H} (121 MHz, CDCl₃): δ 35.1. IR (cm^-1):

(CH), 128.0 (meta-CH, Xy), 128.3 (meta-CH, Xy), 129.7 (CH),

130.2 (CH), 134.6 (ortho-C, Xy), 134.7 (ortho-C, Xy), 136.1 (CH),

136.5 (C), 140.9 (C), 158.2 (C), 163.7 (C1), 183.3 (CdNXy), 216.6

(CO). IR (cm^-1): ν_{Ct N}2207, ν_CdO, ν_CdN, ν_CdC1589, 1563, 1545,

1520. Λ_M(Ω^-1cm²mol^-1): 142.7. Anal. Calcd for

C₃₀H₃₀F₃N₃O₄PdS: C, 52.07; H, 4.37; N, 6.07; S, 4.63. Found: C,

51.63; H, 4.64; N, 5.98; S, 4.72.

ν

_CdO, ν_CdN, ν_CdC1584, 1548, 1516. Λ_M(Ω^-1cm²mol^-1): 163.5.

Anal. Calcd for C₃₉H₃₆F₃N₂O₄PPdS: C, 56.90; H, 4.41; N, 3.40; S,

3.90. Found: C, 56.90; H, 4.74; N, 3.44; S, 3.84.

Synthesis of trans-[PdI₂{C(dNXy)C(Me){CH₂C(O)Me}NH-

C₆H₄-2}(CNXy)] (24). To a solution of 1 (140 mg, 0.21 mmol)

and CH₂Cl₂(15 mL) were successively added HI (28 µL, 0.21

mmol) and XyNC (54.3 mg, 0.42 mmol). After being stirred for

3.5 h the solution was concentrated under vacuum to dryness. The

residue was stirred with Et₂O (2 mL), and the suspension was

ﬁltered. The solid collected was suction dried to give 24 as a yellow

Synthesis of [Pd{C,N,O-C(dNHR)C₆H₄{NC(Me)CHC(Me)O}-

t

2}(CNR)]ClO₄[R ) Bu (21), Xy (22)]. To a solution of 11 (for

21: 60 mg, 0.07 mmol) or 12 (for 22: 60 mg, 0.08 mmol) in acetone

(5 mL) was added 1 equiv of AgClO₄· H₂O. The resulting

suspension was stirred for 30 min, and the solvent was removed

under vacuum to dryness. The residue was stirred with CH₂Cl₂(10

mL) for 10 min, and the suspension was ﬁltered through a short

pad of Celite. The red ﬁltrate was concentrated to ca. 1 mL, and

Et₂O (20 mL) was added to precipitate an orange-red solid, which

was recrystallized from CH₂Cl₂/Et₂O (three times for 21, twice for

1

solid. Yield: 144.1 mg, 87%. Mp: 195 °C (dec). H NMR (400

MHz, CDCl₃): δ 1.50 (s, 3 H, MeCN), 2.06 (s, 3 H, C(O)Me),

2.45 (s, 6 H, Me, Xy), 2.48 (s, 3 H, Me, Xy), 2.75 (s, 3 H, Me,

Xy), 2.86, 3.84 (AB, 2 H, CH₂, J_AB) 18 Hz), 5.70 (s, 1 H, NH),

3260 Organometallics, Vol. 27, No. 13, 2008

Vicente et al.

Table 1. Crystal Data and Structure Reﬁnement of Complexes 1 · 0.5Et₂O, 3 · 0.89CH₂Cl₂· 0.55Et₂O, 5, 10, and 13

1 · 1/2Et₂O

3 · 0.89CH₂Cl₂· 0.55Et₂O

5

7 · 2CH₂Cl₂

10

13

formula

fw

temperature (K)

cryst syst

space group

a (Å)

C

₃₁H₄₁IN₃O_1.5Pd

C

_50.12H_49.34Cl_1.77INO_1.55P₂Pd

C

₁₈H₂₈F₃N₃O₄PdS

C

₃₈H₄₇Cl₄F₃N₃O₄PPdS

C

₂₁H₃₁I₂N₃OPd

C

₄₀H₄₀N₄O₂Pd₂

712.97

133(2)

monoclinic

C2/c

28.5877(18)

10.1558(6)

21.7712(14)

90

91.275(4)

90

6319.3(7)

8

1048.67

100(2)

545.89

133(2)

orthorhombic

P2₁2₁2₁

12.8466(11)

12.9925(11)

13.6154(11)

90

2272.5(3)

4

1.596

978.02

133(2)

monoclinic

P2₁/c

17.7886(18)

13.7537(13)

35.728(4)

90

98.698(4)

90

8640.7(15)

8

701.69

153(2)

triclinic

821.56

298(2)

orthorhombic

Pbca

19.0732(12)

15.3618(11)

24.6074(16)

90

7209.9(8)

8

1.514

triclinic

j

P1

12.1163(5)

13.7556(6)

15.5580(7)

87.638(2)

80.440(2)

64.323(2)

2303.11(17)

2

10.0442(8)

10.8695(9)

13.2366(11)

111.027(2)

92.493(2)

106.846(2)

1273.28(18)

2

b (Å)

c (Å)

R (deg)

ꢀ (deg)

γ (deg)

volume (Å³)

Z

F_calcd(Mg m^-3

)

1.499

1.593

2872

1.512

1.284

1057

1.504

0.817

4000

1.830

3.169

676

µ(Mo KR) (mm^-1

F(000)

)

0.961

1112

1.037

3328

cryst size (mm)

θ range (deg)

no. of rﬂns coll

0.14 × 0.07 × 0.07 0.15 × 0.07 × 0.05

0.18 × 0.10 × 0.10 0.4 × 0.4 × 0.12

0.14 × 0.12 × 0.03 0.24 × 0.13 × 0.08

1.87 to 28.70

60 040

1.64 to 28.23

26 727

2.17 to 30.51

45 144

1.15 to 25.03

102 372

1.67 to 28.70

14 479

1.66 to 26.37

75 487

no. of indep rﬂns/R_int

transmssn

8157/0.046

0.897-0.760

10 315/0.037

0.939-0.831

0/549

1.05

0.0424

0.0887

1.10/-0.60

6937/0.072

no abs corr

0/281

0.98

0.0313

0.0662

0.72/-0.43

15 260/0.127

0.908-0.439

819/995

1.21

0.114

0.253

2.16/-3.63

6424/0.062

0.896-0.594

1/269

0.98

0.0434

0.0721

0.96/-0.95

7371/0.052

0.922-0.789

0/441

1.38

0.0519

0.104

0.69/-0.64

no. of restraints/params 60/328

goodness-of-ﬁt on F²

R₁(I > 2σ(I))

1.02

0.0298

0.0706

0.81/-0.35

wR₂(all reﬂns)

largest diff peak/hole

(e Å^-3

)

6.65 (d, 1 H, Ar, ³J_HH) 8 Hz), 6.98-7.08 (m, 3 H, Ar), 7.13-7.20

(m, 3 H, Ar), 7.25-7.29 (m, 1 H, Ar), 7.36 (m, 1 H, Ar), 8.85 (d,

omitted here, but are deﬁned in Tables 1 and 2. Figures 1–12 show

the ellipsoid representations.

3

1 H, Ar, J_HH) 8 Hz). ¹³C{¹H} NMR (75 MHz, CDCl₃): δ 19.1

Complexes 3, 13, and 17 were measured on a Bruker Smart

APEX diffractometer. Data were collected using monochromated

Mo KR radiation in ω scan mode. Other structures were measured

on a Bruker Smart 1000 diffractometer in ω and φ scan modes.

Absorption corrections were applied on the basis of multiscans

(program SADABS). All structures were reﬁned anisotropically on

F². The NH hydrogens were reﬁned freely, the ordered methyl

groups were reﬁned using rigid groups (AFIX 137), and the other

hydrogens were reﬁned using a riding model. Special features and

exceptions: Complex 1: A substantial region of electron density,

presumably disordered solvent, could not be assigned satisfactorily.

The effects of this solvent were therefore removed mathematically

using the program SQUEEZE (A. L. Spek, University of Utrecht,

Netherlands). A notional amount of 4 diethyl ether per cell (half

per asymmetric unit) was added to the formula; molar mass and

other derived parameters were adjusted accordingly. Complex 3:

The solvent sites were reﬁned as superpositions of dichloromethane

and Et₂O. Complex 5: The Flack parameter reﬁned to -0.03(2);

the compound crystallizes by chance in a chiral space group. No

absorption correction was applied. Complex 7: The crystal quality

was poor (the asymmetric unit contains four dichloromethane

molecules and diffraction is accordingly weak). Nontheless, the

structure could be unambiguously established despite the poor R

values. Methyl hydrogens (except those at C10 and C11) were

included using a riding model assuming perfect staggering (AFIX

33). NH hydrogens were included using a riding model assuming

planarity at nitrogen (AFIX 43). Complex 10: The absorption

correction was numerical, based on face-indexing. Complex 14a:

The acetone molecule is well resolved, but the ether only moderately

resolved; its methyl H’s were included using AFIX 33. Complex

14b: H atoms at C5 and C10 were reﬁned freely. There is no

evidence for disorder involving mutually alternative sites for these

groups. The methyl hydrogens at C37 are poorly resolved, and the

group may be rotationally disordered. The triﬂate is disordered over

two sites with occupation 55:45. The acetone is disordered over a

2-fold axis; its H atoms were not included in the reﬁnement.

Complex 21: Both perchlorates are disordered over two sites (ca.

7:3 and 1:1, respectively), each by rotation about one Cl-O bond.

The butyl group at C18′ is disordered over two sites (ca. 3:1).

(Me), 23.3 (Me), 23.4 (Me), 23.6 (Me), 31.7 (Me), 47.1 (CH₂),

74.1 (C1), 114.8 (CH), 119.6 (CH, Ar), 127.8 (meta-CH, Xy), 128.5

(C), 129.0 (CH, Ar), 129.5 (CH, Ar), 129.6 (CH, Ar), 130.0 (CH,

Ar), 134.9 (C), 136.4 (CH, Ar), 136.5 (C), 137.6 (C), 139.5 (C),

142.2 (CH, Ar), 142.4 (C), 206.5 (CO), 219.2 (CPd). IR (cm^-1):

ν

_NH3348, 3286; ν_CdO, ν_CdC1614.2, 1570.9, 1562.3, 1518.0. Anal.

Calcd for C₂₉H₃₁I₂N₃OPd: C, 43.66; H, 3.92; N, 5.27. Found: C,

43.42; H, 4.10; N, 5.20. Crystals of 24 suitable for an X-ray

diffraction study were obtained by the liquid diffusion method using

CH₂Cl₂and Et₂O.

Synthesis of trans-[PdI₂{C(dNXy)C(Me){CH₂C(O)Me}NH-

C₆H₄-2}(PPh₃)] (25). To a solution of 3 (250 mg, 0.27 mmol) in

CH₂Cl₂(20 mL) were successively added HI (57%, 36 µL, 0.27

mmol) and XyNC (35 mg, 0.27 mmol). After 6 h of stirring the

solution was concentrated under vacuum to ca. 1 mL and Et₂O (20

mL) was added. The suspension was stirred at 0 °C for 15 min and

ﬁltered. The orange solid was collected, washed with Et₂O (3 × 3

mL), and dried by suction and then in an oven at 80 °C for 4 h to

give 25 · H₂O. Yield: 135.4 mg, 53%. Mp: 212 °C (dec). ¹H NMR

(400 MHz, CDCl₃): δ 1.50 (s, 3 H, MeCN), 1.56 (s, 2 H, H₂O),

2.02 (s, 3 H, C(O)Me), 2.51 (s, 3 H, Me, Xy), 2.75 (s, 3 H, Me,

Xy), 2.85, 3.91 (AB, 2 H, CH₂, J_AB) 18 Hz), 5.64 (s, 1 H, NH),

6.62 (d, 1 H, ³J_HH) 8 Hz), 6.97 (d, 1 H, ³J_HH) 8 Hz), 7.29-7.45

(m, 19 H), 8.62 (d, 1 H, ³J_HH) 7 Hz). ¹³C{¹H} NMR (100 MHz,

CDCl₃): δ 23.3 (MeCN), 23.8 (Me, Xy), 23.9 (Me, Xy), 31.7

(C(O)Me), 47.1 (CH₂), 74.2 (d, C1, ²J_CP) 6 Hz), 114.7 (CH, Ar),

3

119.7 (CH, Ar), 127.5 (d, meta-CH, PPh₃, J_CP) 10 Hz), 128.4

3

(d, C, J_CP) 4 Hz), 128.9 (CH, Ar), 129.6 (CH, Ar), 129.7 (d,

4

para-C, PPh₃, J_CP) 2 Hz), 130.1 (CH, Ar), 133.2 (d, ipso-C,

1

2

PPh₃, J_CP) 43 Hz), 135.0 (d, ortho-CH, J_CP) 11 Hz), 135.3

(C), 136.1 (CH, Ar), 138.4 (C, Ar), 139.3 (d, C, J_CP) 5 Hz), 141.7

(d, C, J_CP) 3 Hz), 142.8 (CH, Ar), 206.7 (CO), 221.4 (d, CPd,

²J_CP) 174 Hz). ³¹P{¹H} (121 MHz, CDCl₃): δ 14.5. IR (cm^-1):

ν_NH3385; ν_CdO, ν_CdC1614, 1568, 1514. Anal. Calcd for

C₃₈H₃₉I₂N₂O₂PPd: C, 48.20; H, 4.15; N, 2.96. Found: C, 48.13; H,

3.85; N, 2.99.

X-ray Structure Determinations of Complexes 1, 3, 5, 7, 10,

13, 14a, 14b, 17, 21, 22, and 24. For clarity, solvent contents are

The First 1,2-Dihydroquinazoline-4-yl Complexes

Organometallics, Vol. 27, No. 13, 2008 3261

Table 2. Crystal Data and Structure Reﬁnement of Complexes 14a, 14b, 17, 21, 22, and 24

14a · Et₂O · Me₂CO

₄₉H₅₈F₆N₄O₁₀Pd₂S₂

1253.91

133(2)

monoclinic

P2₁/n

15.7388(11)

20.4783(12)

16.6344(11)

90

93.788(4)

90

5349.6(6)

4

1.557

0.830

14b · 1/2 Me₂CO

17

21

22 · CHCl₃

24

formula

fw

temperature (K)

cryst syst

space group

a (Å)

C

_42.5H₄₄F₃N₄O_5.5Pd₂S

C

₂₉H₂₉N₃OPd

C

₂₁H₃₀ClN₃O₅Pd

C

₃₀H₃₁Cl₄N₃O₅Pd

C

₂₉H₃₁I₂N₃OPd

1000.68

133(2)

monoclinic

C2/c

30.039(3)

13.873(2)

24.189(3)

90

124.729(4)

90

8284.4(18)

8

541.95

100(2)

triclinic

546.33

133(2)

761.78

133(2)

triclinic

797.77

133(2)

monoclinic

P2₁/c

13.9120(11)

23.1974(16)

16.0669(11)

90

113.257(3)

90

4763.8(6)

8

monoclinic

P2₁/c

9.8875(2)

19.6683(4)

16.0188(3)

90

102.8630(10)

90

3037.01(10)

4

j

P1

j

P1

11.0431(5)

15.1683(6)

22.8535(9)

85.293(2)

78.629(2)

89.107(2)

3740.3(3)

6

7.5612(3)

15.6521(6)

15.8294(6)

113.260(3)

97.223(3)

103.022(3)

1627.90(11)

2

b (Å)

c (Å)

R (deg)

ꢀ (deg)

γ (deg)

volume (Å³)

Z

F_calcd(Mg m^-3

)

1.605

0.983

4048

1.444

0.770

1668

1.523

0.927

2240

1.554

0.941

772

1.745

2.669

1544

µ(Mo KR) (mm^-1

F(000)

)

2552

cryst size (mm)

θ range (deg)

no. of rﬂns coll

0.30 × 0.25 × 0.12 0.15 × 0.11 × 0.06

0.27 × 0.19 × 0.08 0.4 × 0.4 × 0.2 0.4 × 0.2 × 0.08 0.37 × 0.25 × 0.18

1.58 to 30.51

126 390

1.65 zo 26.37

54 513

1.56 to 28.16

42 981

1.59 to 30.51

102 353

1.44 to 30.51

39 421

1.67 to 30.51

64 652

no. of indep rﬂns/R_int

transmissn

16 337/0.058

0.907-0.751

55/668

1.06

0.0380

0.0907

1.05/-0.66

8470/0.097

0.943-0.836

615/579

1.07

0.050

0.134

16 639/0.028

0.941-0.819

48/938

1.06

0.0363

0.0821

0.73/-0.40

14 529/0.027

0.836-0.745

135/650

1.06

0.0246

0.0637

0.71/-0.76

9890/0.029

0.929-0.791

18/425

1.05

0.0313

0.0763

0.68/-0.57

9238/0.024

0.645-0.519

0/335

1.05

0.0216

0.0542

1.38/-0.93

no. of restraints/params

goodness-of-ﬁt on F²

R₁(I > 2σ(I))

wR₂(all reﬂns)

largest diff peak/hole (e Å^-3

)

1.64/-0.90

Complex 22: The chloroform is disordered over two sites (ca. 65:

35). Complex 24: The methyl hydrogens at C27 are poorly resolved.

upon the addition of a Et₂O/n-hexane mixture. To remove dba,

the crude product was reﬂuxed in n-hexane and the resulting

suspension ﬁltered while hot. The reaction of 1 with PPh₃(1:2)

in Et₂O gave trans-[PdI(Ar)(PPh₃)₂] (3), which precipitated from

the reaction mixture. When the reaction was carried out using

a 1:1 molar ratio of the reagents, 3 was also obtained, and the

unreacted half of the starting complex 1 was recovered from

the mother liquor. Complex 3 results by replacement of the

chelating N^N ligand by PPh₃and an isomerization process that

Results and Discussion

Synthesis. The oxidative addition of IC₆H₄{NHC(Me)-

CHC(O)Me}-2 (IAr) to Pd(dba)₂was studied in the presence

of various ligands, the nature of which proved to be decisive in

the reaction course. Thus, with bidentate N^N ligands (1:1:1,

at room temperature, in toluene under nitrogen atmosphere) the

reaction gave complexes [PdI(Ar)(N^N)] (N^N ) 4,4′-tert-

t

butyl-2,2′-bipyridine ) Bubpy (1), N,N,N′,N′-tetramethyleth-

ylenediamine ) tmeda (2)) in good yield (Scheme 1). Some

metallic palladium formed, which was removed by ﬁltration

through a short pad of Celite. Complex 1 is partly soluble in

Et₂O and precipitated along with some dibenzylideneacetone

Figure 1. Thermal ellipsoid representation plot (50% probability)

of complex 1 · 0.5Et₂O. Selected bond lengths (Å) and angles (deg):

Pd-N(31) ) 2.0741(19), Pd-N(21) ) 2.1281(19), Pd-I )

2.5700(3), Pd-C(11) ) 1.993(2), C(11)-C(12) ) 1.395(3),

N(1)-C(12) )1.427(3), N(1)-C(1) ) 1.346(3), C(1)-C(2) )

1.376(4),C(2)-C(3))1.413(4),O-C(3))1.256(3),C(11)-Pd-N(31)

) 94.87(8), N(31)-Pd-N(21) ) 78.47(7), C(11)-Pd-I ) 88.11(7),

N(21)-Pd-I)98.09(5),C(1)-N(1)-C(12))126.6(2),N(1)-C(1)-C(2)

) 121.2(2), C(1)-C(2)-C(3) ) 123.8(2), O-C(3)-C(2) )

123.7(2).

Figure 2. Thermal ellipsoid representation plot (50% probability)

of complex 3. Selected bond lengths (Å) and angles (deg):

Pd(1)-P(2) ) 2.3250(9), Pd(1)-P(1) ) 2.3349(9), Pd(1)-I(1) )

2.6901(3), Pd(1)-C(1) ) 2.020(3), C(1)-C(6) ) 1.395(5),

C(6)-N(1) ) 1.419(5), N(1)-C(7) ) 1.339(4), C(7)-C(8) )

1.390(5),C(8)-C(9))1.412(5),C(9)-O(1))1.255(4),C(1)-Pd(1)-P(2)

) 87.81(9), C(1)-Pd(1)-P(1) ) 87.46(9), P(2)-Pd(1)-I(1) )

91.77(2), P(1)-Pd(1)-I(1) ) 92.60(2), C(7)-N(1)-C(6) ) 129.9(3),

N(1)-C(7)-C(8) ) 120.2(3), C(7)-C(8)-C(9) ) 124.2(3),

O(1)-C(9)-C(8) ) 123.9(3).

3262 Organometallics, Vol. 27, No. 13, 2008

Vicente et al.

Figure 5. Thermal ellipsoid representation plot (50% probability)

of complex 10. Selected bond lengths (Å) and angles (deg):

Pd-C(17) ) 2.014(5), Pd-I(1) ) 2.6076(5), Pd-I(2) ) 2.6164(5),

Pd-C(7) ) 1.991(4), N(1)-C(7) ) 1.293(5), N(1)-C(8) )

1.502(5), C(1)-C(7) ) 1.497(5), N(2)-C(2) ) 1.440(5), N(2)-C(13)

) 1.323(6), C(13)-C(14) ) 1.375(6), C(14)-C(15) ) 1.409(6),

C(15)-O ) 1.258(5), N(3)-C(17) ) 1.141(5), C(7)-Pd-I(1) )

89.46(11), C(17)-Pd-I(1) ) 91.29(14), C(7)-Pd-I(2) ) 88.71(11),

C(17)-Pd-I(2))90.62(14),N(1)-C(7)-Pd)127.1(3),C(7)-N(1)-C(8)

) 131.5(4), N(1)-C(7)-C(1) ) 115.8(3), C(13)-N(2)-C(2) )

126.7(4), N(2)-C(13)-C(14) ) 121.1(4), O-C(15)-C(14) )

Figure 3. Thermal ellipsoid representation plot (50% probability)

of the cation of complex 5. Selected bond lengths (Å) and angles

(deg): Pd-C(2) ) 2.089(2), Pd-N(3) ) 2.166(2), Pd-N(2) )

2.197(2), Pd-C(11) ) 2.009(3), C(12)-N(1) ) 1.420(4), C(1)-N(1)

) 1.306(3), C(1)-C(2) ) 1.451(4), C(2)-C(3) ) 1.494(4),

O(1)-C(3))1.213(3),C(11)-Pd-C(2))84.87(10),C(11)-Pd-N(3)

) 97.39(9), C(2)-Pd-N(2) ) 94.20(9), N(3)-Pd-N(2) ) 83.59(8),

C(1)-N(1)-C(12) ) 124.2(2), N(1)-C(1)-C(2) ) 121.3(2),

C(1)-C(2)-C(3) ) 117.3(2), O(1)-C(3)-C(2) )123.3(3).

122.2(4), N(3)-C(17)-Pd

)176.7(5).

) 175.2(4), C(17)-N(3)-C(18)

dihydroquinolinium complexes [Pd{C,C-C₆H₄{NHdC(Me)CHC-

t

(O)Me}-2}(N^N)]TfO (N^N ) Bubpy (4), tmeda (5)) were

isolated in moderate yields (Scheme 1). The coordination to

Pd of the methine carbon, after removal of the iodo ligand, can

beattributedtotheelectronicdelocalizationovertheN-C-C-C-O

skeleton (see below), which confers negative charge on the

methine C atom (and also the O atom, with a positive charge at

N), to the more carbophilic than oxophilic character of Pd, as

expected for a soft cation, and to the six-membered nature of

the chelate ring. The Pd-C(sp³) bond in these complexes is

easily cleaved upon the addition of NaI or neutral ligands L

(1:1) to give the starting complexes (1 or 2) or cationic

t

derivatives [Pd(Ar)(N^N)(L)] (N^N ) Bubpy, L ) PPh₃(6),

N^N ) tmeda, L ) PPh₃(7), ^tBuNC (8)), respectively, in good

yields. Complex 8 was obtained along with a small amount of

t

the complex resulting from the insertion of BuNC into the

Pd-C_arylbond (16b, see below), which was isolated from the

mother liquor.

(15) Albert, J.; Bosque, R.; Cadena, J. M.; Granell, J. R.; Muller, G.;

Ordinas, J. I. Tetrahedron: Asymmetry 2000, 11, 3335. Albert, J.; Cadena,

J. M.; Delgado, S.; Granell, J. J. Organomet. Chem. 2000, 603, 235. Albert,

J.; Cadena, J. M.; Granell, J. R.; Solans, X.; Font Bardia, M. Tetrahedron:

Asymmetry 2000, 11, 1943. Larraz, C.; Navarro, R.; Urriolabeitia, E. P.

New J. Chem. 2000, 24, 623. Lohner, P.; Pfeffer, M.; Fischer, J. J.

Organomet. Chem. 2000, 607, 12. Fernandez, S.; Navarro, R.; Urriolabeitia,

E. P. J. Organomet. Chem. 2000, 602, 151. Albert, J.; Bosque, R.; Cadena,

J. M.; Delgado, S.; Granell, J. J. Organomet. Chem. 2001, 634, 83. Amatore,

C.; Bahsoun, A. A.; Jutand, A.; Meyer, G.; Ntepe, A. N.; Ricard, L. J. Am.

Chem. Soc. 2003, 125, 4212. Carbayo, A.; Cuevas, J. Y.; Garcia Herbosa,

G.; Garcia Granda, S.; Miguel, D. Eur. J. Inorg. Chem. 2001, 2361. Carbayo,

A.; Cuevas, J. V.; Garcia Herbosa, G. J. Organomet. Chem. 2002, 658, 15.

Crespo, M.; Granell, J.; Solans, X.; Fontbardia, M. J. Organomet. Chem.

2003, 681, 143. Fernandez, A.; Vazquez Garcia, D.; Fernandez, J. J.; Lo´pez

Torres, M.; Suarez, A.; Castro Juiz, S.; Vila, J. M. Eur. J. Inorg. Chem.

2002, 2389. Fernandez-Rivas, C.; Cardenas, D. J.; Martin-Matute, B.;

Monge, A.; Gutierrez-Puebla, E.; Echavarren, A. M. Organometallics 2001,

20, 2998. Jalil, M. A.; Fujinami, S.; Nishikawa, H. J. Chem. Soc., Dalton

Trans. 2001, 1091. Lo´pez, C.; Caubet, A.; Pe´rez, S.; Solans, X.; Font-

Bard´ıa, M. J. Organomet. Chem. 2003, 681, 82. Marshall, W. J.; Grushin,

V. V. Organometallics 2003, 22, 555. Ng, J. K. P.; Chen, S.; Li, Y.; Tan,

G. K.; Koh, L. L.; Leung, P. H. Inorg. Chem. 2007, 46, 5100. Casas, J. M.;

Fornies, J.; Fuertes, S.; Martin, A.; Sicilia, V. Organometallics 2007, 26,

1674.

Figure 4. Thermal ellipsoid representation plot (30% probability)

of one of the two independent cations of complex 7. See Supporting

Information for bond lengths and angles.

is probably promoted by the great transphobia^11–14of the Ph₃P/

Ar ligand pair.¹⁵These results contrast with those obtained by

reacting equimolecular amounts of IC₆H₄N(R)(CH₂)_nC(O)R′ (R

) benzyl, R′ ) Me, n ) 3; R ) Me, R′ ) NMe₂, CO₂Me, n )

2), Pd(dba)₂, and PPh₃, affording four-membered C,N pallada-

cyclic complexes.^1a,16

The reactions of 1 or 2 with TlTfO (TfO ) CF₃SO₃, 1:1 in

acetone) precipitated TlI immediately, and the 4-pallada-3,4-

(11) Vicente, J.; Arcas, A.; Ferna´ndez-Herna´ndez, J. M.; Bautista, D.;

Jones, P. G. Organometallics 2005, 24, 2516.

(12) Vicente, J.; Abad, J. A.; Shaw, K. F.; Gil-Rubio, J.; Ram´ırez de

Arellano, M. C.; Jones, P. G. Organometallics 1997, 16, 4557.

(13) Vicente, J.; Saura-Llamas, I.; Gru¨nwald, C.; Alcaraz, C.; Jones,

P. G.; Bautista, D. Organometallics 2002, 21, 3587. Vicente, J.; Abad, J. A.;

Herna´ndez-Mata, F. S.; Jones, P. G. J. Am. Chem. Soc. 2002, 124, 3848.

Vicente, J.; Abad, J. A.; Mart´ınez-Viviente, E.; Jones, P. G. Organometallics

2002, 21, 4454. Vicente, J.; Arcas, A.; Ga´lvez-Lo´pez, M. D.; Jones, P. G.

Organometallics 2006, 25, 4247.

(16) Sole´, D.; Vallverdu´, L.; Sola´ns, X.; Font-Bard´ıa, M.; Bonjoch, J.

J. Am. Chem. Soc. 2003, 125, 1587. Sole´, D.; Serrano, O. Angew. Chem.,

Int. Ed. 2007, 46, 7270.

(14) Vicente, J.; Abad, J. A.; Fo¨rtsch, W.; Jones, P. G.; Fischer, A. K.

Organometallics 2001, 20, 2704.

The First 1,2-Dihydroquinazoline-4-yl Complexes

Organometallics, Vol. 27, No. 13, 2008 3263

Figure 7. Thermal ellipsoid representation plot (30% probability)

of the cation of complex 14a. Selected bond lengths (Å) and angles

(deg): Pd(1)-C(2) ) 1.937(2), Pd(1)-N(4) ) 2.008(2), Pd(1)-N(1)

) 2.040(2), Pd(1)-O(2) ) 2.1263(18), Pd(2)-C(1) ) 1.943(3),

Pd(2)-N(3) ) 2.008(2), Pd(2)-N(2) ) 2.050(2), Pd(2)-O(1) )

2.1298(19), C(1)-N(1) ) 1.283(3), C(2)-N(2) ) 1.291(3),

C(11)-O(2) ) 1.233(3), C(10)-C(11) ) 1.499(4), C(9)-C(10)

) 1.506(4), C(9)-N(4) ) 1.283(3), C(42)-N(4) ) 1.433(3),

C(2)-C(41) ) 1.491(3), C(6)-O(1) ) 1.231(3), C(5)-C(6) )

1.510(4), C(4)-C(5) ) 1.511(4), C(4)-N(3) ) 1.285(3), C(22)-N(3)

) 1.437(3), C(1)-C(21) ) 1.494(3), C(31)-N(1) ) 1.450(3),

C(51)-N(2))1.451(3),C(2)-Pd(1)-N(4))81.72(9),C(2)-Pd(1)-N(1)

) 94.93(9), N(4)-Pd(1)-O(2) ) 88.85(8), N(1)-Pd(1)-O(2) )

94.57(8), C(1)-Pd(2)-N(3) ) 81.59(10), C(1)-Pd(2)-N(2) )

95.26(9), N(3)-Pd(2)-O(1) ) 88.60(8), N(2)-Pd(2)-O(1) )

94.48(8), N(1)-C(1)-Pd(2) ) 124.60(18), N(2)-C(2)-Pd(1) )

123.96(18), C(1)-N(1)-Pd(1) ) 121.69(17), C(2)-N(2)-Pd(2)

) 122.12(17), N(3)-C(4)-C(5) ) 119.3(2), N(4)-C(9)-C(10)

) 119.1(2), C(6)-C(5)-C(4) ) 118.1(2), C(11)-C(10)-C(9) )

118.4(2), O(1)-C(6)-C(5) ) 122.8(2), O(2)-C(11)-C(10) )

124.3(2), C(4)-N(3)-Pd(2) ) 123.70(18), C(9)-N(4)-Pd(1) )

125.48(18), C(6)-O(1)-Pd(2) ) 120.37(18), C(11)-O(2)-Pd(1)

)119.95(17).

Figure 6. Thermal ellipsoid representation plot (50% probability)

of complex 13. Selected bond lengths (Å) and angles (deg):

Pd(1)-C(9) ) 1.954(4), Pd(1)-N(2) ) 2.002(3), Pd(1)-O(1) )

2.067(3), Pd(1)-N(3) ) 2.068(3), Pd(2)-C(29) )1.931(4),

Pd(2)-N(4) ) 2.013(3), Pd(2)-N(1)) 2.067(3), Pd(2)-O(2) )

2.072(3), N(1)-C(9) ) 1.290(5), N(1)-C(1) ) 1.448(5), N(3)-C(29)

) 1.294(5), N(3)-C(21) ) 1.447(5), N(2)-C(16) ) 1.329(5),

N(4)-C(36) ) 1.326(6), C(16)-C(17) ) 1.401(7), C(36)-C(37)

) 1.395(7), C(17)-C(18) ) 1.386(8), C(37)-C(38) ) 1.391(7),

O(1)-C(18) ) 1.257(6), O(2)-C(38) ) 1.270(5), C(9)-Pd(1)-N(2)

) 82.82(15), N(2)-Pd(1)-O(1) ) 93.20(14), C(9)-Pd(1)-N(3)

) 96.99(15), O(1)-Pd(1)-N(3) ) 87.85(13), C(29)-Pd(2)-N(4)

) 81.44(15), C(29)-Pd(2)-N(1) ) 96.36(14), N(4)-Pd(2)-O(2)

) 92.58(13), N(1)-Pd(2)-O(2) ) 89.99(12), C(15)-N(2)-Pd(1)

) 110.1(2), C(35)-N(4)-Pd(2) ) 110.6(3), C(10)-C(9)-Pd(1)

) 109.8(3), C(30)-C(29)-Pd(2) ) 111.1(3), C(18)-O(1)-Pd(1)

) 119.2(3), C(38)-O(2)-Pd(2) ) 119.0(3), O(1)-C(18)-C(17)

) 126.7(4), O(2)-C(38)-C(37) ) 127.3(4), N(2)-C(16)-C(17)

) 122.3(4), N(4)-C(36)-C(37) ) 122.4(4), C(16)-N(2)-Pd(1)

) 123.1(3), C(36)-N(4)-Pd(2) ) 122.3(3).

When the oxidative addition of IAr to Pd(dba)₂was carried

out in the presence of RNC ligands (R ) C₆H₃Me₂-2,6 (Xy),

^tBu, 1:1:2, at room temperature, in toluene under nitrogen

atmosphere) complex mixtures (by NMR) formed, from which

only low yields of [Pd₂I₂(CNXy)₄]¹⁷(9, 16%) or trans-

[PdI₂{C(dNH^tBu)Ar}(CN^tBu)] (10, 28%) (Scheme 1), respec-

tively, could be isolated, while the expected [PdI(Ar)(CNR)₂]

compounds, analogous to 3, were not detected. Complex 9 has

been prepared recently¹⁷from [Pd₂(µ-I)₂(P^tBu₃)₂] and XyNC;

it was identiﬁed only by its elemental analyses and IR spectrum,

but no NMR data were reported. Previous syntheses of this type

of complexes involved comproportionation reactions of Pd(0)

and Pd(II) isocyanide derivatives.¹⁸We have postulated the

formationof9inthedecompositionoftrans-[Pd{C(O)C₆H₄NHC(O)-

NHTo-2}I(CNXy)₂]²and have isolated other members of the

family [Pd₂X₂(CNR)₄] (X/R ) Cl/^tBu,¹¹Xy;¹²Br/^tBu,¹⁹Xy²⁰)

by reacting aryl or alkyl palladium complexes with isocyanides.

We have studied the reactions of complexes 1 and 2 with

t

RNC (R ) Xy, Bu) and found that the results depend on (1)

the molar ratio of the reagents, (2) the R substituent in the

isocyanide, and (3) the N^N ligand present in the starting

palladium complex. Thus, when 1 or 2 is treated with ﬁve or

more equivalents of isocyanide, complex trans-[PdI{C(d

t

NR)Ar}(CNR)₂] (R ) Bu (11), Xy (12); Scheme 1) forms in

almost quantitative yield. The process involves insertion of one

RNC into the Pd-Ar bond, the replacement of N^N by two

RNC ligands, and a cis to trans isomerization process probably

driven by the different transphobia^11–14between ligands. Similar

results have been previously found in the reactions of various

[PdX(Ar)(N^N)] complexes with isocyanide,^{2,14,19,21,22}although,

in some cases, polyinsertion processes have also been ob-

served.²¹

The reaction of 5 with XyNC (1:1 molar ratio) also involved

the insertion of the isocyanide into the Pd-Ar bond, but,

(17) Dura`-Vila`, V.; Mingos, D. M. P.; Vilar, R.; White, A. J. P.;

Williams, D. J. J. Organomet. Chem. 2000, 600, 198.

(18) Otsuka, S.; Tatsuno, Y.; Ataka, K. J. Am. Chem. Soc. 1971, 93,

6705. Rettig, M. F.; Kirk, E. A.; Maitlis, P. M. J. Organomet. Chem. Chem.

1976, 111, 113. (c) Boehm, J. R.; Balch, a. L. Inorg. Chem. 1977, 16, 778.

(19) Vicente, J.; Saura-Llamas, I.; Gruenwald, C.; Alcaraz, C.; Jones,

P. G.; Bautista, D. Organometallics 2002, 3587.

(21) Vicente, J.; Abad, J. A.; Mart´ınez-Viviente, E.; Jones, P. G.

Organometallics 2002, 4454. Van Baar, J. F.; Klerkz, J. M.; Overbosch,

P.; Stufkens, D. J.; Vrieze, K. J. Organomet. Chem. 1976, 112, 95.

(22) Uson, R.; Fornies, J.; Espinet, P.; Lalinde, E.; Jones, P. G.;

Sheldrick, G. M. J. Organomet. Chem. 1983, 253, C47. Uson, R.; Fornies,

J.; Espinet, P.; Garc´ıa, A.; Toma´s, M.; Foces-Foces, C.; Cano, F. H. J.

Organomet. Chem. 1985, 282, C35.

(20) Vicente, J.; Abad, J. A.; Mart´ınez-Viviente, E.; Jones, P. G.

Organometallics 2003, 22, 1967.

3264 Organometallics, Vol. 27, No. 13, 2008

Vicente et al.

Figure 8. Thermal ellipsoid representation plot (30% probability)

of complex 14b. Selected bond lengths (Å) and angles (deg):

Pd(1)-C(2) ) 1.932(6), Pd(1)-N(4) ) 2.026(5), Pd(1)-N(1) )

2.043(5), Pd(1)-O(2) ) 2.131(4), Pd(2)-C(1) ) 1.949(6),

Pd(2)-N(3) ) 1.989(5), Pd(2)-N(2) ) 2.048(5), Pd(2)-O(1) )

2.078(4), C(1)-N(1) ) 1.286(7), C(2)-N(2) ) 1.282(7), C(11)-O(2)

) 1.219(8), C(10)-C(11) ) 1.498(9), C(9)-C(10) ) 1.500(9),

C(9)-N(4) ) 1.284(8), C(42)-N(4) ) 1.441(8), C(2)-C(41) )

1.503(8), C(6)-O(1) ) 1.266(7), C(5)-C(6) ) 1.394(9), C(4)-C(5)

) 1.412(9), C(4)-N(3) ) 1.318(8), C(22)-N(3) ) 1.412(7),

C(1)-C(21) ) 1.487(8), C(31)-N(1) ) 1.470(7), C(51)-N(2) )

1.456(7), C(2)-Pd(1)-N(4) ) 81.3(2), C(2)-Pd(1)-N(1) )

95.1(2), N(4)-Pd(1)-O(2) ) 88.30(18), N(1)-Pd(1)-O(2) )

95.45(17), C(1)-Pd(2)-N(3) ) 81.8(2), C(1)-Pd(2)-N(2) )

95.4(2), N(3)-Pd(2)-O(1) ) 90.78(18), N(2)-Pd(2)-O(1) )

92.14(17), N(1)-C(1)-Pd(2) ) 124.3(4), N(2)-C(2)-Pd(1) )

124.0(4), C(1)-N(1)-Pd(1) ) 122.0(4), C(2)-N(2)-Pd(2) )

122.7(4), N(3)-C(4)-C(5) ) 121.3(6), N(4)-C(9)-C(10) )

119.1(6), C(6)-C(5)-C(4) ) 128.3(6), C(11)-C(10)-C(9) )

120.5(6), O(1)-C(6)-C(5) ) 126.2(6), O(2)-C(11)-C(10) )

124.4(6), C(4)-N(3)-Pd(2) ) 123.3(4), C(9)-N(4)-Pd(1) )

125.0(4), C(6)-O(1)-Pd(2) ) 120.4(4), C(11)-O(2)-Pd(1) )

120.8(4).

Figure 9. Thermal ellipsoid representation plot (50% probability)

of complex 17. Selected bond lengths (Å) and angles (deg) for one

of the independent molecules: Pd(1)-C(1) ) 1.958(2), Pd(1)-C(11)

) 1.988(2), Pd(1)-N(3) ) 2.031(2), Pd(1)-O(1) ) 2.0928(17),

N(1)-C(1) ) 1.150(3), N(2)-C(11) ) 1.269(3), N(2)-C(12) )

1.408(3), C(11)-C(21) ) 1.497(3), C(21)-C(22) ) 1.397(3),

N(3)-C(22) ) 1.419(3), N(3)-C(31) ) 1.332(3), C(31)-C(32)

) 1.409(4), C(32)-C(33) ) 1.390(4), O(1)-C(33) ) 1.277(3),

C(1)-Pd(1)-C(11) ) 97.11(10), C(11)-Pd(1)-N(3) ) 83.14(9),

C(1)-Pd(1)-O(1) ) 87.50(9), N(1)-C(1)-Pd(1) ) 170.6(2),

N(2)-C(11)-Pd(1) ) 133.73(19), C(11)-N(2)-C(12) ) 125.5(2),

C(21)-C(11)-Pd(1) ) 108.89(16), C(22)-C(21)-C(11) ) 117.1(2),

C(21)-C(22)-N(3) ) 114.4(2), C(22)-N(3)-Pd(1) ) 111.59(15),

C(31)-N(3)-Pd(1) ) 122.92(17), N(3)-C(31)-C(32) ) 123.1(2),

C(33)-C(32)-C(31) ) 128.9(2), O(1)-C(33)-C(32) ) 127.2(2),

C(33)-O(1)-Pd(1) ) 121.00(16).

X-ray diffraction. The 1:1 reaction between 13 and HTfO

produced a solid, for which the ¹H NMR spectrum showed broad

resonances at room temperature. At low temperature (-40 °C),

signals corresponding to 13 and a different complex containing

four Me resonances, probably 14b (1:2 molar ratio), were

observed. Recrystallization of the isolated mixture led to an

increase in the proportion of 13. This suggests that 14b is in an

equilibrium displaced to the formation 13. Reactions of 14a with

half an equivalent of Na₂CO₃or with 1 equiv of 13 gave

respectively either a complex mixture or the starting materials.

Dinuclear complexes with bridging iminoacyl ligands were

known previously, and the crystal structures of seven of them

have been reported.^22,23However, apart from the iminoacyl

ligands, these complexes bear from two to four additional

ligands in order to attain the tetracordination of the Pd atoms,

whereas 13, 14a, and 14b contain only iminoacyl ligands.

Complex 13 is robust, and its iminoacyl bridges do not split

unless it is reﬂuxed in CHCl₃with phosphine or isocyanide

ligands for at least 9 h, giving mononuclear neutral C,N,O-pincer

additionally, deprotonation of the iminic nitrogen by the tmeda

ligand takes place, resulting in a C,N,O-pincer fragment that,

in the absence of an additional ligand, dimerizes upon the

coordination of the pendant iminoacyl nitrogen atom to give

the ꢀ-ketiminato complex [Pd{µ-N,C,N′,O-N(Xy){dCC₆H₄-

{NC(Me)CHC(Me)O}-2}}]₂(13) (Scheme 2). The byproducts,

1/2 (H₂tmeda)(TfO)₂+ 1/2 tmeda, were removed by washing

the crude reaction mixture with cold MeOH. The insertion of

the isocyanide is probably responsible for the change of

coordination of the ortho substituent, because otherwise the

resulting C,C-palladacycle would be a seven-membered ring.

Instead, deprotonation of the iminium proton by the replaced

tmeda ligand allows formation of a ﬁve-membered C,N-

palladacycle, which, together with the six-membered chelate

ring resulting from the O-enolato coordination, leads to a pincer

complex. The reaction of 13 with an excess of HTfO produced

protonation of both methine groups in the ortho substituent,

resulting in the formation of the dicationic complex [Pd{µ-

O,N,C,N′-OC(Me)CH₂C(Me)NC₆H₄CdNXy}]₂(TfO)₂(14a;

Scheme 2). When formation of single crystals of 14a was

attempted, single crystals of the monoprotonated complex

[Pd{µ-O,N,C,N′-OC(Me)CHC(Me)NC₆H₄CdNXy}{µ-N,C,N′,O-

N(Xy){dCC₆H₄{NC(Me)CH₂C(Me)O}-2}}]TfO (14b) were

also isolated, which allowed the study of both complexes by

(23) Uson, R.; Fornies, J.; Espinet, P.; Lalinde, E.; Jones, P. G.;

Sheldrick, G. M. J. Chem. Soc., Dalton Trans. 1982, 2389. Uson, R.;

Fornies, J.; Espinet, P.; Lalinde, E.; Garc´ıa, A.; Jones, P. G.; Meyer-Base,

K.; Sheldrick, G. M. J. Chem. Soc., Dalton Trans. 1986, 259. Dupont, J.;

Pfeffer, M.; Daran, J. C.; Jeannin, Y. Organometallics 1987, 6, 899.

Zograﬁdis, A.; Polborn, K.; Beck, W.; Markies, B. A.; van Koten, G. Z.

Naturforsch., B: Chem. Sci. 1994, 49, 1494. Canovese, L.; Visentin, F.;

Santo, C.; Levi, C.; Dolmella, A. Organometallics 2007, 26, 5590.

The First 1,2-Dihydroquinazoline-4-yl Complexes

Organometallics, Vol. 27, No. 13, 2008 3265

Figure 12. Thermal ellipsoid representation plot (30% probability)

of complex 24. Selected bond lengths (Å) and angles (deg):

Pd-C(20) ) 2.0056(19), Pd-C(4) ) 2.0130(16), Pd-I(2) )

2.60390(19), Pd-I(1) ) 2.61461(18), N(3)-C(4) ) 1.330(2),

C(2)-N(3) ) 1.526(2), N(1)-C(2) ) 1.443(2), N(1)-C(8A) )

1.359(2), C(4A)-C(8A) ) 1.417(2), C(4)-C(4A) ) 1.451(2),

N(2)-C(20))1.141(2),C(20)-Pd-C(4))176.49(7),C(20)-Pd-I(2)

) 86.73(6), C(4)-Pd-I(2) ) 94.51(5), C(20)-Pd-I(1) ) 90.70(6),

C(4)-Pd-I(1))87.47(5),I(2)-Pd-I(1))168.930(70),N(3)-C(4)-C(4A)

) 117.01(14), C(4)-N(3)-C(2) ) 119.10(13), N(1)-C(2)-N(3)

)105.11(13),C(8A)-N(1)-C(2))117.72(15),N(1)-C(8A)-C(4A)

)118.07(16), C(8A)-C(4A)-C(4) ) 118.24(16), N(2)-C(20)-Pd

) 177.1(2), C(20)-N(2)-C(21) ) 177.3(2).

Figure 10. Thermal ellipsoid representation plot (50% probability)

of the cation of complex 21. Selected bond lengths (Å) and angles

(deg): Pd(1)-C(17) ) 1.9831(17), Pd(1)-C(7) ) 1.9883(16),

Pd(1)-N(2) ) 2.0045(14), Pd(1)-O(1) ) 2.0506(12), O(1)-C(15)

) 1.282(2), C(14)-C(15) ) 1.393(3), C(13)-C(14) ) 1.400(2),

N(2)-C(13) ) 1.332(2), N(2)-C(2) ) 1.414(2), C(1)-C(2) )

1.409(2), N(1)-C(7) ) 1.301(2), N(1)-C(8) ) 1.500(2), N(3)-C(17)

) 1.148(2), C(17)-Pd(1)-C(7) ) 101.53(7), C(7)-Pd(1)-N(2)

) 80.09(6), C(17)-Pd(1)-O(1) ) 87.13(6), N(2)-Pd(1)-O(1) )

91.71(5), C(15)-O(1)-Pd(1) ) 122.06(11), O(1)-C(15)-C(14)

)126.65(16),C(15)-C(14)-C(13))127.81(16),N(2)-C(13)-C(14)

) 122.10(15), C(2)-N(2)-Pd(1) ) 111.07(10), C(1)-C(2)-N(2)

) 113.90(14), C(2)-C(1)-C(7) ) 113.21(14), N(1)-C(7)-C(1)

) 116.43(15), N(1)-C(7)-Pd(1) ) 134.46(13), C(7)-N(1)-C(8)

) 130.10(15), N(3)-C(17)-Pd(1) ) 173.29(15).

These complexes are soluble even in n-pentane, which accounts

for the moderate isolated yields (58-62%). Complex 13 does

not react with PPNCl (PPN ) PPh₃dNdPPh₃) after 10 h

reﬂuxing in CHCl₃.

Compound 15 was protonated by excess HTfO at both the

methine carbon and the imine nitrogen to give [Pd{C,N,O-

C(dNHXy)C₆H₄{NdC(Me)CH₂C(O)Me}-2}(PPh₃)](TfO)₂

(18), containing a neutral C,N,O-pincer ligand. However, under

the same reaction conditions, protonation of 16a or 17 occurs

only at the imine nitrogen, giving complexes [Pd{C,N,O-

C(dNHXy)C₆H₄{NC(Me)CHC(Me)O}-2}(L)]TfO (L ) ^tBuNC

(19), XyNC (20)), containing a monoanionic C,N,O-pincer

ligand (Scheme 2). The greater nucleophilic character of the

CH carbon in 15 compared to that in the homologous 17

suggests that the XyNC ligand is more electron-withdrawing

than PPh₃. Complexes [Pd{C,N,O-C(dNHR)C₆H₄{NC(Me)-

t

CHC(Me)O}-2}(CNR)]ClO₄(R ) Bu (21), Xy (22)), homo-

logues of 19 and 20, were obtained by reacting 11 or 12,

respectively, with AgClO₄(1:1, in acetone, Scheme 2). In these

reactions, the coordination vacancy at the Pd center promotes

a rare isocyanide replacement by an O donor ligand; the NH

deprotonation by the imine N, required for the formation of the

monoanionic C,N,O-pincer ligand, shows again, as in the

synthesis of 19 and 20, the greater nucleophilic character of

the imine N than the methine carbon.

Figure 11. Thermal ellipsoid representation plot (50% probability)

of the cation of complex 22. Selected bond lengths (Å) and angles

(deg): Pd-C(20) ) 1.9659(18), Pd-C(30) ) 1.9677(18), Pd-N(1)

) 2.0110(14), Pd-O(1) ) 2.0441(13),O(1)-C(4) ) 1.283(2),

C(3)-C(4) ) 1.387(3), C(2)-C(3) ) 1.408(3), N(1)-C(2) )

1.330(2), N(1)-C(11) ) 1.414(2), C(11)-C(12) ) 1.409(2),

C(12)-C(20) ) 1.475(2), N(2)-C(20) ) 1.301(2), N(2)-C(21)

) 1.443(2), N(3)-C(30) ) 1.151(2), N(3)-C(31) ) 1.404(2),

C(20)-Pd-C(30) ) 99.66(7), C(20)-Pd-N(1) ) 81.76(6),

C(30)-Pd-O(1))85.73(6),N(1)-Pd-O(1))92.86(6),C(4)-O(1)-Pd

) 121.29(13), O(1)-C(4)-C(3) ) 126.80(18), C(4)-C(3)-C(2)

) 128.30(17), N(1)-C(2)-C(3) ) 122.56(17), C(2)-N(1)-Pd )

122.26(12), C(11)-N(1)-Pd ) 112.12(10), C(12)-C(11)-N(1)

) 114.38(15), C(12)-C(20)-Pd ) 110.90(12), C(20)-N(2)-C(21)

) 125.79(16), N(3)-C(30)-Pd ) 169.51(16), C(30)-N(3)-C(31)

) 174.99(19).

Complexes 21 and 22 were isolated together with a small

amount of replaced isocyanide, and their puriﬁcation required

repeated recrystallization from CH₂Cl₂and Et₂O, thus lowering

the yield somewhat. Both complexes crystallized as hydrates

1

(with 1.5 or 1 molecule of water, respectively, from H NMR

data and elemental analyses). After being heated at 80 °C for

6 h, 21 decomposed and 22 did not dehydrate. The treatment

of these complexes with M₂CO₃(M ) Na, Tl, 1:0.5, Scheme

2) affords complexes 16b and 17. Complex [Pd{C,N,O-

C(dNHXy)C₆H₄{NC(Me)CHC(Me)O}-2}PPh₃]TfO (23), the

PPh₃homologue of 19-22, forms in the reaction of 15 with

the equimolar amount of HTfO, but is better obtained by reacting

14a with PPh₃(1:2, 65 °C, 10 h). In this reaction, the dimer is

complexes [Pd{C,N,O-C(dNXy)C₆H₄{NC(Me)CHC(Me)O}-

2}(L)] (L ) PPh₃(15), ^tBuNC (16a), XyNC (17)) (Scheme 2).

3266 Organometallics, Vol. 27, No. 13, 2008

Vicente et al.

Scheme 1

split and one proton migrates from the methylene to the imine

N atom (Scheme 2). As far as we are aware, complexes 13-23,

along with one cobalt²⁴and two other palladium complexes^2,25

bearing C,C,O-, C,N,N-, and C,N,C-pincer ligands, respectively,

are the only pincer complexes of any transition metal in which

at least one metalated carbon atom belongs to an iminoacyl

fragment.²⁶

and HI. When L₂) tmeda, this base neutralizes all HI formed,

giving 0.5 equiv of the salt (H₂tmeda)I₂and leaving an unreacted

t

0.5 equiv of tmeda. However, when L₂) Bubpy, the imine

nitrogen of the still unreacted complex A is more nucleophilic

than free L₂, and the HI formed, together with the still unreacted

XyNC, affords B (L′ ) XyNC), which is an analogue of 10.

However, the NH addition to the C(Me)-CH bond required in

B to give 24 does not occur in 10 because of the less acidic

character of the ^tBuNH group. When L ) PPh₃, the reaction is

similar, but only 1 equiv of L is replaced (L′ ) PPh₃). This

proposal is supported by the synthesis of pure 24 in 87% yield

from 1, HI, and XyNC in 1:1:2 molar ratio. Similarly, 25 was

obtained from the reaction of 3 with HI and XyNC (1:1:1). The

source of 24 is not 17 because it does not react with HI. As far

as we are aware, 24 and 25 are the ﬁrst 1,2-dihydroquinazoline-

4-yl complexes of any metal. Complexes 24 and 25, like 10,

adopt a trans geometry, in spite of the strong C/C and C/P

transphobia,^11–14because this is the most common structure for

a diiodo complex.

We have mentioned above that reaction of 1 or 2 with excess

XyNC gives 12. However, reactions of 1-3 with XyNC in a

1:2 (1, 2) or 1:1.5 (3) Pd:XyNC molar ratio afford different

products depending on the nature of the neutral ligands present

in the starting complex. Thus, the reaction of the tmeda complex

2 with XyNC (1:2) produced half an equivalent each of

(H₂tmeda)I₂and free tmeda, as in the synthesis of 13, along

with the neutral pincer complex 17 (Scheme 2). However, when

1 or 3 was reacted with XyNC in 1:2 or 1:1.5 molar ratio,

respectively, a mixture was obtained of half an equivalent each

of 17 and the 1-H-2-methyl-2-acetonyl-3-xylyl-1,2-dihydro-

quinazolin-4-ylderivativetrans-[PdI₂{C(dNXy)C(Me){CH₂C(O)Me}-

NHC₆H₄-2}L] (L ) XyNC (24), PPh₃(25)) (Scheme 3), which

can easily be separated because 17 is soluble in Et₂O.

Scheme 4 shows a reasonable reaction pathway to explain

these results. Reaction of complexes 1-3 with 1 equiv of XyNC

should afford complex A after the insertion of the isocyanide

into the Pd-C bond. This intermediate reacts with another

equivalent of XyNC to afford 17, L₂(^tBubpy, tmeda, or 2 PPh₃),

The pincer ligands in complexes 20 and 22 or in 17 can be

viewed as resulting from the quinazolyl ligand present in 24,

after cleavage of the N-C bond formed in its synthesis, mono-

or dideprotonation, respectively (Scheme 5), and removal of

the two iodo ligands. In fact, we have succeeded in preparing

22 or 17 in almost quantitative yield by reacting 24 with 2 equiv

of AgClO₄(room temperature, acetone, 30 min) or 1 equiv of

Tl₂CO₃(reﬂuxing in acetone, 30 min), respectively. We assume

that the cleavage of the C-N bond of the quinazolyl ligand

and the deprotonation of the methylene group affording 22 occur

through complex C (Scheme 5), whose dicationic nature confers

it a markedly acid character. Therefore, 22 is formed, like its

(24) Yamamoto, Y.; Tanase, T.; Sugano, K. J. Organomet. Chem. 1995,

486, 21.

(25) Kim, Y. J.; Chang, X. H.; Han, J. T.; Lim, M. S.; Lee, S. W. Dalton

Trans. 2004, 3699.

(26) CCDC CSD version 5.28 (November 2006, updated May 2, 2007),

2006.

The First 1,2-Dihydroquinazoline-4-yl Complexes

Organometallics, Vol. 27, No. 13, 2008 3267

Scheme 2

Scheme 3

3268 Organometallics, Vol. 27, No. 13, 2008

Vicente et al.

Scheme 4

Scheme 5

homologue 20, in the presence of a strong acid (HClO₄or TfOH,

respectively). The reaction of 24 with Tl₂CO₃causes the

deprotonation of the intermediate 20, giving 17.

All the structures display some common features. Thus, in

all cases, the Pd atom is in a distorted square-planar environ-

ment; the mean deviations from planarity for the Pd atom and

its four immediate neighbors is e0.05 Å except for 24 (0.10

Å, associated with the nonlinearity of the I-Pd-I moiety, angle

168.93(1)°). When N^N chelating ligands are present, the

It is noteworthy that, apart from the ability of the aryl ligand

Ar to act as monocoordinate (I, Chart 2) or C,C-chelating (II),

the insertion of RNC into the Pd-C_arylbond gives rise to seven

different ligands, some of them mutually related through acid/

base reactions. These include monocoordinate neutral (III) and

monoanionic (IV) iminoacyl ligands; terdentate dianionic (V),

monoanionic (VI, VII), or neutral (VIII) C,N,O-pincer ligands,

and the 1,2-dihydroquinazolin-4-yl ligand (IX). Additionally,

in complexes 13 and 14 the C,N,O-pincer ligands use their

pendant iminoacyl nitrogen atoms to coordinate a second metal

center, thus acting as dianionic or monoanionic tetradentate

N,C,N,O-bridging pincer ligands.

X-ray Crystal Structures. The crystal structures of com-

plexes 1, 3, 5, 7, 10, 13, 14a, 14b, 17, 21, 22, and 24 have

been determined, although that of 7 is of poor quality (see

above). The two independent cations of 7 are closely similar,

as are those of 21 and three independent molecules of 17.

t

N-Pd-N angles are less than 90° (1, Bubpy, 78.47(7)°; 5, 7,

tmeda, 83.59(8)°, 83.4(4)°, respectively). In the pincer com-

plexes 13, 14a, 14b, 21, and 22 the C-Pd-N angles in the

ﬁve-membered ring are narrower (82.82(15)° and 81.44(15)°,

81.72(9)°, 81.8(2)°, 80.096(6)°, 81.16(6)°, respectively) than the

N-Pd-O angle in the more ﬂexible six-membered ring

(93.20(14)° and 92.58(13)°, 88.85(9)° and 88.60°, 88.30(18)°

and 90.78(18)°, 91.71(5)°, 92.86(6)°, respectively). The Pd-C_Ar

bond distances in complexes 1, 3, 5, and 7 (1.993-2.009 Å) or

the Pd-C_iminein complexes 10, 13, 14a, 14b, 17, 21, 22, and

24 (1.931(4)-2.0130(16) Å) are in the ranges found in aryl or

iminoacyl complexes of Pd previously reported (Pd-C_aryl

,

1.96-2.06 Å; Pd-C_(dN), 1.95-2.07 Å).²⁶

The First 1,2-Dihydroquinazoline-4-yl Complexes

Organometallics, Vol. 27, No. 13, 2008 3269

Table 3. Classical Hydrogen Bonds (Å, deg)

Chart 2

complex

D-H · · · A

d(D-H) d(H · · · A) d(D · · · A) (DHA)

1

3

5

7

N(1)-H(1) · · · O

0.80(3) 1.99(3) 2.665(3) 141(3)

0.79(4) 2.00(4) 2.664(4) 142(3)

0.81(3) 2.05(3) 2.841(3) 166(3)

N(1)-H(1) · · · O(1)

N(1)-H(1) · · · O(2)

N(1)-H(1) · · · O(1)

0.88

1.93

1.91

2.662(14) 139.0

2.649(13) 141.0

N(1′)-H(1′) · · · O(1′) 0.88

10

N(1)-H(1) · · · O#1

N(2)-H(2) · · · O

N(2)-H(2) · · · O#1

#1: 1-x,1-y,-z

0.81(3) 2.07(3) 2.863(4) 168(4)

0.81(3) 2.10(4) 2.647(4) 125(4)

0.81(3) 2.35(3) 3.072(5) 149(4)

21

N(1)-H(1) · · · O(2)

0.83(2) 2.27(2) 3.092(2) 169(2)

N(1′)-H(1′) · · · O(2′) 0.80(2) 2.46(2) 3.220(2) 160(2)

22

24

N(2)-H(2) · · · O(2)

N(1)-H(1) · · · O#1

#1: 2-x,1-y,2-z

0.76(2) 2.18(3) 2.924(2) 168(2)

0.81(3) 2.16(3) 2.957(2) 169(2)

In complexes 5, 14a, and 14b, the coordination or protonation

of the methine group interrupts the electronic delocalization over

theN-C-C-C-Ogroup,makingtheN-C(Me)(1.306(3)-1.283(3)

Å) and C-O (1.213(3)-1.233(3) Å) distances shorter and the

MeC(N)-C(1.451(4)-1.511(4)Å)andC-C(O)Me(1.494(4)-1.510(4)

Å) lengths longer than those in their precursors, approaching

NdC and CdO double bonds or C-C single bonds, respec-

2

tively. The C_sp²-C_sp³-C_spangles are rather wide (117.3(2)°,

118.1(2)°, 118.4(2)°) for an sp³carbon.

Pd-O distances are shorter in the anionic pincer ligand

(2.0441(13)-2.0922(18) Å) than that in the cationic ligand

(2.1263(18)-2.131(4) Å), as expected for the stronger enolato

O-Pd than carbonyl O-Pd bond.

The CdNXy bond distances in 17 (1.269(3), 1.274(3),

1.271(3) Å) are similar to those found in other iminoacyl

palladium complexes and shorter than the CdNHR lengths in

its cationic homologues (R ) ^tBu (21), Xy (22), 1.301(2) Å) or

in 10 (N(1)-C(7) ) 1.293(5) Å), which, in turn, are similar to

that found in the only similar structurally characterized pal-

ladium complex, namely, [Pd{C(Me)dNHXy}Cl(dppe)]BF₄

(1.291(6) Å).²⁸

Inthedinuclearcomplexes,thecentralN(1)-C(9)-N(3)-C(29)

(13) or C(1)-N(1)-C(2)-N(2) (14a,b) fragment is planar

(mean deviation, 0.04, 0.03 0.02 Å, respectively), and this plane

subtends the Pd-C-N plane angles of 35.6°, 37.1° (13), 37.3°,

34.4° (14a), and 37.1°, 33.9° (14b), leading to a boat

conformation.

3

The trans inﬂuence sequence C_aryl> C_sp> PPh₃> I is

responsible for the slightly different Pd-N bond distances in

complexes containing N^N chelating ligands 1 (2.1281(19) vs

2.0741(19) Å), 5 (2.197(2) vs 2.166(2) Å), and 7 (2.207(10) vs

2.190(9) Å). All other structural parameters are unremarkable.

Intramolecular classical hydrogen bonds of the form N-H · · · O

are observed in complexes 1, 3, 7, and 10. Intermolecular or

cation/anion N-H · · · O hydrogen bonds between the NH group

of the ortho substituent with the oxygen of the carbonyl group

(10, 24) or a triﬂate anion (5) or between the iminoacyl NH

Most bond distances at the ortho substituent of the aryl ligand

in complexes 1, 3, 7, and 10 or pincer complexes 13, 14b, 17,

21, and 22 (N-C(Me): 1.318(8)-1.346(3) Å, C(Me)-CH:

1.375(6)-1.412(9) Å, CH-C(O)Me: 1.386(8)-1.499(4) Å,

C-O: 1.233(3)-1.283(2) Å) are intermediate between those

reported for single and double bonds (C_sp²-N_sp³: 1.416 Å,

C_sp²dN_sp²: 1.316 Å; C_sp²-C_sp²: 1.455 Å, C_sp²)C_sp²: 1.326 Å;

C_sp²-C_sp²(CdO): 1.464 Å, C_sp²)C_sp²(CdO): 1.340 Å; C_sp²-O:

1.333 Å, C_sp²dO: 1.210 Å).²⁷In the schemes we have

represented this situation by showing an electronic delocalization

over the N-C-C-C-O group.

-

and one oxygen of the ClO₄anion (21, 22; in 21 the ordered

perchlorate oxygen is involved, the other three are disordered

about the local 3-fold axis) or the carbonyl oxygen (10; dimer

formation, Figure 16) are also observed (Table 3).

“Weak” hydrogen bonds of the form C-H · · · O, C-H · · · F,

or C-H · · · I and in some cases C-H · · · Pd (H · · · I and

H · · · Pd distances of about 3.0-3.3 Å indicate the borderline

nature of the contacts) are present in several of the complexes;

for reasons of space, these are not included in Table 3 (see

(27) Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen,

A. G.; Taylor, R. J. Chem. Soc., Perkin Trans. 2 1987, S1.

(28) Owen, G. R.; Vilar, R.; White, A. J. P.; Williams, D. J. Organo-

metallics 2003, 22, 4511.

3270 Organometallics, Vol. 27, No. 13, 2008

Vicente et al.

Figure 16. Dimer formation in complex 10 via classical hydrogen

bonds (including a three-centrr interaction).

Figure 13. Dimer formation via bifurcated (C-H)₂· · · O interactions

in complex 1. The distance between the stacked ring centroids is

3.7 Å. The symmetry operator is 1/2-x, 1/2-y,1-z.

one of the three presumably activated hydrogens at C5 and

C10 makes a short contact to a triﬂate. Compound 21: The

disordered perchlorates preclude a meaningful discussion of

H · · · O interactions. There is an intramolecular Pd1 · · · H11A

contact of 2.69 Å; in the second cation it is 2.84 Å. The two

independent molecules are arranged such that O1′ of the

second molecule makes an axial contact of 3.23 Å to Pd1.

Compound 22: The perchlorate oxygens are acceptors in one

classical and four C-H · · · O interactions, forming layers

j

parallel to (011) (Figure 17). Compound 24: The structural

role of “borderline” H · · · Pd and H · · · I contacts is well

illustrated here. The hydrogens H33 and H34 are involved

in a bifurcated contact to Pd (3.39, 2.96 Å) over an inversion

center, and H34 is additionally close to the neighboring I

atom (3.33 Å). Combined with the classical hydrogen bond,

the overall effect is to form ribbons of molecules parallel to

[101] (Figure 18). There is also an intramolecular contact

Pd · · · H5 of 2.76 Å.

Figure 14. Dimer formation via bifurcated (C-H)₂· · · I interactions

in complex 3. The symmetry operator is 1-x, -y, -z

NMR Spectroscopy. The replacement of iodine in IAr by

a [Pd] or C(dNR)[Pd] moiety (complexes 1-3, 6-8, or

10-12, respectively) produces changes in the shielding of a

few nuclei of the ortho substituent of Ar. Thus, most MeCN,

C(O)Me, CH, and NH resonances appear in the ranges

2.00-1.62, 2,24-1.95, 5.21-4.99, and 12.67-11.94 ppm,

respectively, which compare well with those of IAr at 1.85,

2.13, 5.25, and 12.29 ppm. However, MeCN protons in 3

(1.03 ppm), 6 (1.34 ppm), and 7 (1.35) and CH proton in 3

(4.83 ppm) appear outside the above ranges, probably because

of their shielding by one of the aryl rings of PPh₃(see Figures

2 and 4). In contrast, the NH protons in complexes 6-8

(13.08-13.69 ppm) are signiﬁcantly deshielded with respect

to ArI, because they are cationic, although the NH proton in

the neutral complex 2 (13.07 ppm) is also deshielded.

Similarly,carbonMeCN(22.0-19.8ppm),C(O)Me(31.5-28.1

ppm), C2 (98.7-97.7 ppm), C1 (163.4-157.3 ppm), and CO

(196.1-193.5) nuclei resonate near the corresponding values

in ArI at 19.6, 29.2, 97.7, 159.6, and 196.5 ppm, respectively,

although it is noticeable that in all complexes MeCN and

CO resonances are deshielded (by 0.2-2.4 ppm) and shielded

(by 0.4-3 ppm), respectively, with respect to ArI.

C1 coordination of the Ar ligand in 4 and 5 causes, with

respect to their precursors (Scheme 1), deshielding of MeCN

protons (by 0.75 and 0.58 ppm, respectively), probably because

of their cationic nature, and shielding of the CH proton (by 0.62

and 1.50 ppm, respectively), because of metal coordination. It

is surprising that the NH proton in 4 is deshielded by 0.58 ppm

with respect to that in 1 but shielded by 0.75 ppm in 5 with

respect to 2.

Pincer complexes 13, 15-17, and 19-22 show resonances

corresponding to the proton at 2.38-2.12 (MeCN), 2.04-1.70

(C(O)Me), and 5.19-4.92 (CH) ppm and to carbon at 24.3-22.4

(MeCN),27.4-25.8(C(O)Me),105.4-102.8(C2),and163.7-161.8

(C1) ppm regardless of the nuclearity or the charge of the

Figure 15. “Tetrafurcate” hydrogen bond system (C-H)₄· · · O in

complex 7. The H · · · O distances lie in the range 2.41-2.65 Å.

Supporting Information). The effects of the more important

weak interactions (a subjective assessment!) may be sum-

marized as follows. Compound 1: Molecules are arranged

in pairs across inversion centers by bifurcated (C-H)₂· · · O

interactions from the bipy ligands (Figure 13). 3: Molecules

are arranged in pairs by bifurcated (C-H)₂· · · F interactions

from the triphenylsphosphine ligands (Figure 14). Compound

5: Two C-H · · · O interactions to the carbonyl oxygen and

three C-H · · · O and two C-H · · · F to the triﬂate result in a

complex three-dimensional packing (not shown). Compound

7: Twelve C-H · · · O and three C-H · · · F interactions to the

triﬂate result in thick layers of residues parallel to the xy

1

plane at z ≈ /₄,³/₄(not shown); one interesting feature is a

(C-H)₄· · · O system (Figure 15). Compound 10: The in-

tramolecular contact H9A · · · Pd is very short at 2.53 Å.

Compound 14a: Seven C-H · · · O interactions to the triﬂate

and one to the acetone lead to a complex three-dimensional

packing (not shown). Compound 14b: The triﬂate disorder

makes a discussion of limited value. It is surprising that only

The First 1,2-Dihydroquinazoline-4-yl Complexes

Organometallics, Vol. 27, No. 13, 2008 3271

Figure 17. Packing diagram of complex 22. Perchlorates are drawn with thick bonds; H · · · O interactions are indicated by thick dashed

j

bonds. One layer parallel to (011) is shown.

Figure 18. Packing diagram of complex 24. H · · · O, H · · · Pd, and H · · · I interactions are indicated by thick dashed bonds. The net effect

is to form a ribbon of molecules parallel to [101].

complex. However, the resonance for the CO carbon nucleus

is deshielded for cationic complexes 19-22 (215.6-217.1 ppm)

and the neutral dinuclear complex 13 (207.8 ppm) with respect

to neutral 15-17 complexes (182.9-182.1 ppm).

The mono- or diprotonation of the pincer ligands in 13 or 15

deshields mainly the MeCN and C(O)Me protons and the C1

carbon nuclei (by 0.53 or 0.44, by 0.66 or 0.48, and by 16.5 or

17.4 ppm, respectively) in complex 14a or 18, respectively, and

the CO carbon nucleus in 18 (by 34.5 ppm).

atom bonded to Pd was shown in the ¹³C{¹H} NMR spectrum

to appear at 228 ppm with a ²J_CPcoupling constant of 147 Hz.

Conclusions

The study of the reactivity of the functionalized iodoarene IAr

toward Pd(dba)₂in the presence of various N donor ligands, and

the insertion reaction of isocyanides into the Pd-C_arylbond present

in the resulting ortho-palladated derivatives, has allowed us to

prepare a wide variety of complexes containing novel aryl,

iminoacyl, or C,N,O-pincer ligands as well as some 1,2-dihydro-

quinazolin-4-ylpalladium complexes, which, as far as we are aware,

are the ﬁrst such derivatives of any metal. The complexes described

are connected through a rich acid/base chemistry.

The resonance from the iminoacyl carbon bonded to Pd

appears for the non-pincer complexes 11 and 12 at 166.5 and

174.2, respectively, for the neutral (15-18) or cationic (19-22)

pincer derivatives in the ranges 178.2-179.0 and 181.8-183.3

ppm, respectively, or for the dicationic complexes 14a and 18

at 200.5 and 191.5 ppm, respectively, which is probably related

to the positive charge supported by the palladium atom in each

case.

Acknowledgment. Dedicated to Profs. Juan Fornie´s, M.

Pilar Garc´ıa, Jose´ Gimeno, and Miguel Yus on the occasion of

their 60th birthday (1947 was an excellent vintage!). We thank

Ministerio de Ciencia y Tecnolog´ıa and FEDER for ﬁnancial

support (CTQ2004-05396) and for a grant to A.J.M.M.

In complexes 24 and 25 we assigned the resonance of the

quinazolyl carbon bonded to palladium on the basis of a recent

paper²⁹

reporting

a

Pd

complex

bearing

a

Supporting Information Available: CIF ﬁles for complexes 1,

3, 5, 7, 10, 13, 14a, 14b, 17, 21, 22, and 24. Nonclassical hydrogen

bond parameters. This material is available free of charge via the

Internet at http://pubs.acs.org.

C-C(dNEt₂)CHdCHPh ligand trans to PPh₃, in which the C

(29) Albe´niz, A. C.; Espinet, P.; Pe´rez-Mateo, A.; Nova, A.; Ujaque,

G. Organometallics 2006, 1293.

OM800205G

Article Doi

New palladacycles containing terdentate [C,N,O]n- (n = 0, 1, 2) or tetradentate [N,C,O,N′]n- in = 1, 2 ligands. the first 1,2-dihydroquinazoline-4-yl complexes

DOI: 10.1021/om800205g

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Article abstract of DOI:10.1021/om800205g

Full text of DOI:10.1021/om800205g

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