Mono(2,6-dinitroaryl)platinum(II) and Mono- and Bis(2,6-dinitroaryl) platinum(IV) Complexes

Organometallics 2009, 28, 3501–3517

3501

Mono(2,6-dinitroaryl)platinum(II) and Mono- and

Bis(2,6-dinitroaryl)platinum(IV) Complexes

Jose´ Vicente,^†Aurelia Arcas,*^,†and Mar´ıa-Dolores Ga´lvez-Lo´pez

Grupo de Qu´ımica Organometa´lica, Departamento de Qu´ımica Inorga´nica, Facultad de Qu´ımica,

UniVersidad de Murcia, Aptdo. 4021, E-30071 Murcia, Spain

Peter G. Jones^‡

Institut fu¨r Anorganische und Analytische Chemie, Technische UniVersita¨t Braunschweig, Postfach 3329,

38023 Braunschweig, Germany

Delia Bautista^§

SAI, UniVersidad de Murcia, Aptdo. 4021, E-30071 Murcia, Spain

ReceiVed February 27, 2009

cis-[Pt(κ²-Ar)(κ¹-Ar)(OH₂)] (κ²-Ar ) κ²C,O-C₆(NO₂)₂-2,6-(OMe)₃, κ¹Ar ) κC-C₆(NO₂)₂-2,6-(OMe)₃)

reacts either (1) with hydrochloric acid (1:1) to afford cis- and trans-[Pt(κ²-Ar)(µ-Cl)]₂(1a) and C₆H(NO₂)₂-

2,6-(OMe)₃(HAr) or (2) with MeC(O)X (1:1) in the presence of atmospheric moisture to give 1a or 1b

(X ) Br). These complexes react (1) with bidentate ligands to afford [Pt(κ¹-Ar)X(L^∧L)] (X ) Cl, L^∧L

) bpy (2a); X ) Br, L^∧L ) 1,5-cyclooctadiene (cod; 2b), norbornadiene (nbd; 2c)), (2) with Tl(acac)

to give [Pt(κ²-Ar)(acac-κ²O,O)] (3), and (3) with monodentate neutral ligands to render complexes resulting

from bridge splitting or/and cleavage of the Pt-O bond ([Pt(κ¹-Ar)BrL₂] (L ) MeCN (4a), XyNC (Xy

) C₆H₃Me₂-2,6; 4b), [Pt(κ²-Ar)BrL] (L ) MeCN (5a), XyNC (5b), CO (5c)), [Pt(κ¹-Ar)(µ-X)L]₂(X )

Br, L ) 3-hexyne (6a), ethylene (6b), styrene (6c); X ) Cl, L ) PPh₃(6d)), depending on the nature of

the ligand and the molar ratio of the reagents. Complex 6d reacts (1) with monodentate neutral ligands

to give [Pt(κ¹-Ar)Cl(PPh₃)L] (L ) PPh₃(7), SMe₂(8a), CO (8b), XyNC (8c1)), (2) with Tl(acac) to

afford [Pt(κ¹-Ar)(acac-κ²O,O)(PPh₃)] (9), (3) with (PPN)Cl to render anionic (PPN)[Pt(κ¹-Ar)Cl₂(PPh₃)]

(PPN · 10), or (4) with bpy leading to cationic [Pt(κ¹-Ar)(bpy)(PPh₃)]Cl (11 · Cl). If 1 equiv of bpy is

used in the latter reaction, the intermediate [Pt(κ¹-Ar)(bpy)(PPh₃)][Pt(κ¹-Ar)Cl₂(PPh₃)] (11 · 10) is obtained.

The reaction of excess Cl₂with cis-[Pt(κ²-Ar)(κ¹-Ar)(H₂O)] or trans-[Pt(κ²-Ar)(κ²-Ar)(CO)] gives (OC-

6-32)-[Pt(κ²-Ar)₂Cl₂] (12) or (OC-6-22)-[Pt(κ²-Ar)₂Cl₂] (13), respectively. Complex 13 gradually transforms

in solution into 12. The dimer 6d reacts with 3 equiv of PhICl₂to afford fac-[Pt(κ²-Ar)Cl₃(PPh₃)] (14).

AgClO₄reacts with complex 12, leading to (OC-6-32)-[Pt(κ²-Ar)₂(OH₂)₂](ClO₄)₂· Et₂O (15 · Et₂O).

Complex 12 reacts with 1 equiv of PPh₃to afford cis-[Pt(κ²-Ar)(κ¹-Ar)PPh₃] or with AsPh₃, leading to

cis-[Pt(κ²-Ar)(κ¹-Ar)AsPh₃] (16, 2:1 molar ratio) or (AsPh₃OH)[Pt(κ²-Ar)(κ¹-Ar)Cl] (17) (1:1 molar ratio).

X-ray crystal structures of HAr and complexes 2a · CH₂Cl₂, 2c, 3, 5a, trans-6b, trans-6c · CDCl₃, trans-

7 · Et₂O, 8a, 8c, 9, 11 · 10 · 2CHCl₃, 12, 13, 16 · CHCl₃, and 17 have been determined.

ture transmetalation from [Hg(κ¹-Ar)₂] to [PtCl₄]^2-and a family

of diaryl Pt(II) complexes derived from it. However, all attempts

to obtain monoaryl Pt(II) complexes by reacting [HgAr₂] with

Introduction

We are involved in the study of the reactivity of organomer-

cury complexes as transmetalating agents to prepare organo-

metallic compounds of Au,¹Pd,²Pt,³Rh,⁴Sn,⁵and Tl.⁶In this

context, we have reported the synthesis of the diaryl complex

cis-(NMe₄)[Pt(κ²-Ar)(κ¹-Ar)Cl] (κ²-Ar ) κ²C,O-C₆(NO₂)₂-2,6-

(OMe)₃, κ¹-Ar ) κ¹C-C₆(NO₂)₂-2,6-(OMe)₃) by high-tempera-

(2) See for example: Vicente, J.; Abad, J. A.; Jones, P. G. Organome-

tallics 1992, 11, 3512. Vicente, J.; Abad, J. A.; Gil-Rubio, J.; Jones, P. G.;

Bembenek, E. Organometallics 1993, 12, 4151. Vicente, J.; Abad, J. A.;

Shaw, K. F.; Gil-Rubio, J.; Ram´ırez de Arellano, M. C.; Jones, P. G.

Organometallics 1997, 16, 4557.

(3) See for example: Vicente, J.; Abad, J. A.; Teruel, F.; Garc´ıa, J. J.

Organomet. Chem. 1988, 345, 233. Vicente, J.; Arcas, A.; Ferna´ndez-

Herna´ndez, J. M.; Bautista, D. Organometallics 2006, 25, 4404.

(4) Vicente, J.; Martin, J.; Chicote, M. T.; Solans, X.; Miravitlles, C.

J. Chem. Soc., Chem. Commun. 1985, 1004. Vicente, J.; Martin, J.; Solans,

X.; Font-Altaba, M. Organometallics 1989, 8, 357. Vicente, J.; Abad, J. A.;

Lahoz, F. J.; Plou, F. J. J. Chem. Soc., Dalton Trans. 1990, 1459.

(5) See for example: Brianso´, J. L.; Sola´ns, X.; Vicente, J. J. Chem.

Soc., Dalton Trans. 1983, 169. Vicente, J.; Chicote, M. T.; Ram´ırez-de-

Arellano, M. C.; Pelizzi, G.; Vitali, F. J. Chem. Soc., Dalton Trans. 1990,

279.

^†E-mail: jvs1@um.es (J.V.); aurelia@um.es (A.A.). Web: http://

www.um.es/gqo/.

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

complexes should be addressed. E-mail: p.jones@tu-bs.de.

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

and 13 should be addressed. E-mail: dbc@um.es.

(1) See for example: Vicente, J.; Chicote, M. T.; Arcas, A.; Artigao,

M. Inorg. Chim. Acta 1982, 65, L251. Vicente, J.; Chicote, M. T.; Arcas,

A.; Artigao, M.; Jime´nez, R. J. Organomet. Chem. 1983, 247, 123. Vicente,

J.; Arcas, A.; Chicote, M. T. J. Organomet. Chem. 1983, 252, 257. Vicente,

J.; Chicote, M. T.; Bermu´dez, M. D.; Sa´nchez-Santano, M. J.; Jones, P. G.;

Fittschen, C.; Sheldrick, G. M. J. Organomet. Chem. 1986, 310, 401.

(6) Vicente, J.; Abad, J. A.; Gutierrez-Jugo, J. F.; Jones, P. G. J. Chem.

Soc., Dalton Trans. 1989, 2241.

10.1021/om9001582 CCC: $40.75

2009 American Chemical Society

Publication on Web 05/05/2009

3502 Organometallics, Vol. 28, No. 12, 2009

Vicente et al.

1

4.07 (s, 6 H, OMe), 3.87 (s, 6 H, OMe). H NMR (400 MHz,

(Me₄N)₂[Pt₂Cl₆] or K₂[PtCl₄] in a 1:1 molar ratio were unfruitful.

Instead, diaryl Pt(II) complexes and the starting platinum

complex were isolated.⁷However, we have recently reported a

rare example of Pt to Hg transmetalation allowing the prepara-

tion of the monoaryl complex trans-[Pt(κ¹-Ar)(µ-Cl)(PPh₃)]₂.⁸

Here we report the syntheses from this complex of new

monoaryl Pt complexes of the types [Pt(κ¹-Ar)Cl(PPh₃)L],

[Pt(κ¹-Ar)Cl₂(PPh₃)]^-, and [Pt(κ¹-Ar)(PPh₃)L₂]⁺. However, as

these complexes always contain PPh₃as a neutral ligand, we

have used another synthetic procedure that affords the complexes

[Pt(κ²-Ar)(µ-X)]₂(X ) Cl, Br), thus extending the range of

monoaryl complexes to those of the types [Pt(κ²-Ar)X(L)],

[Pt(κ²-Ar)(acac)], [Pt(κ¹-Ar)(µ-X)L]₂, and [Pt(κ¹-Ar)XL₂]. In

addition, we report the synthesis and reactivity of some nitroaryl

acetone-d₆): δ 4.14 (s, 6 H, OMe), 4.10 (s, 6 H, OMe), 3.94 (s, 6

H, OMe). H NMR (400 MHz, acetone-d₆, -30 °C, a:b isomers

1:0.5): isomer a, δ 4.15 (s, 6 H, OMe), 4.08 (s, 6 H, OMe), 3.91

(s, 6 H, OMe); isomer b, δ 4.13 (s, 6 H, OMe), 4.07 (s, 6 H, OMe),

3.90 (s, 6 H, OMe). H NMR (400 MHz, acetone-d₆, -75 °C, a:b

isomers 1:1): isomer a, δ 4.16 (s, 6 H, OMe), 4.06 (s, 6 H, OMe),

3.882 (s, 6 H, OMe); isomer b, δ 4.15 (s, 6 H, OMe), 4.04 (s, 6 H,

OMe), 3.887 (s, 6 H, OMe). Anal. Calcd for C₁₈H₁₈Cl₂N₄O₁₄Pt₂:

C, 22.58; H, 1.86; N, 5.74. Found: C, 22.49; H, 1.90; N, 5.55.

1

Solution A was concentrated to dryness, and the residue was

extracted with Et₂O. The resulting solution was concentrated to

dryness to give a colorless solid that was identiﬁed as HAr. FAB⁺:

m/z 259 (M + H⁺). H NMR (400 MHz, CDCl₃): δ 8.16 (s, 1 H,

1

CH), 4.11 (s, 6 H, OMe), 3.98 (s, 3 H, OMe). ¹³C{¹H} NMR

(100.81 MHz, CDCl₃): δ 152.34 (m-C), 148.81 (p-C), 138.57 (o-

C), 116.65 (CH), 62.68 (m-OMe), 61.71 (p-OMe). Single crystals

of HAr were obtained by slow evaporation of a CD₂Cl₂/Et₂O

solution of HAr.

Pt(IV) complexes of the types [Pt(κ²-Ar)₂X₂], [Pt(κ²-Ar)₂L₂]²⁺

,

and [Pt(κ²-Ar)X₃L]. The only reported nitroaryl Pt(IV) com-

plexes are a few derivatives of [Pt(κ²C,O-C₆H₄NO₂-2)₂].⁹

Synthesis of [Pt₂(K²-Ar)₂(µ-Br)₂] (1b). Acetyl bromide (27 µL,

0.36 mmol) was added to a solution of [Pt(κ²-Ar)(κ¹-Ar)(OH₂)]

(0.36 mmol) in CH₂Cl₂(15 mL). The solution was stirred until it

became a suspension, which was concentrated to dryness, and

CHCl₃(1 mL) was added. The resulting suspension was ﬁltered,

the solid was stirred with CHCl₃(2 mL), and this mixture was

centrifuged. The resulting red solid (144 mg) was dissolved in the

minimum quantity of CHCl₃, and the solution was centrifuged. The

decanted solution was concentrated (1 mL) and the resulting

suspension was ﬁltered to give 1b as a red solid. Yield: 138 mg,

Experimental Section

Unless otherwise stated, the reactions were carried out without

precautions to exclude light or atmospheric oxygen or moisture.

The IR (Nujol/polyethylene), C, H, and N analyses, and melting

point determinations were carried out as described elsewhere.¹⁰

Molar conductivities were measured in Me₂CO (ca. 5 × 10^-4mol

L^-1) with a Crison Micro CM2200 conductimeter. FAB⁺was

obtained on an Autospec 5000 VG spectrometer. NMR spectra were

recorded with Varian Unity 300 and Bruker AC 200 and Avance

300 and 400 spectrometers at room temperature unless otherwise

stated. Chemical shifts were referred to TMS (¹H) or H₃PO₄

(³¹P{¹H}). The NMR probe temperature was calibrated using

ethylene glycol ¹H NMR standard methods. The spectra of complex

8b were recorded under a CO atmosphere. The ligands κC-

C₆(NO₂)₂-2,6-(OMe)₃and κ²C,O-C₆(NO₂)₂-2,6-(OMe)₃are repre-

sented by κ¹-Ar and κ²-Ar. The complex trans-[Pt(κ¹-Ar)(µ-

Cl)(PPh₃)]₂(6d),⁸trans-[Pt(κ²-Ar)(κ¹-Ar)(CO)],¹¹and CH₂Cl₂

solutions of cis-[Pt(κ²-Ar)(κ¹-Ar)(OH₂)]⁷were prepared as reported

previously.

1

72%. H NMR (300 MHz, CDCl₃, a:b isomers 1:1): isomer a, δ

4.14 (s, 6 H, OMe), 4.06 (s, 6 H, OMe), 3.87 (s, 6 H, OMe); isomer

b, 4.15 (s, 6 H, OMe), 4.05 (s, 6 H, OMe), 3.87 (s, 6 H, OMe).

Anal. Calcd for C₁₈H₁₈Br₂N₄O₁₄Pt₂: C, 20.31; H, 1.70; N, 5.26.

Found: C, 20.06; H, 1.69; N, 5.08.

Synthesis of [PtCl(K¹-Ar)(bpy)] (2a). To a stirred suspension

of 1a (48 mg, 0.05 mmol) in CH₂Cl₂(4 mL) was added bpy (15

mg, 0.1 mmol). The resulting yellow solution was concentrated to

dryness, and the residue was stirred with Et₂O (2 mL). The

suspension was ﬁltered, and the solid was washed with Et₂O and

air-dried to give 2a · CH₂Cl₂as a yellow solid. Yield: 59 mg, 93%.

Synthesis of [Pt(K²-Ar)(µ-Cl)]₂(1a) and HAr. Method a. To

a solution of [Pt(κ²-Ar)(κ¹-Ar)(OH₂)]⁷(0.35 mmol) in CH₂Cl₂(15

mL) was added HCl (36%, 30 µL, 0.35 mmol). The solution was

stirred to give a suspension, which was concentrated to dryness,

and CHCl₃(1 mL) was then added. The resulting suspension was

ﬁltered, the solid was stirred with CHCl₃(3 mL), and the suspension

was centrifuged. The decanted solution was concentrated (1 mL),

and 1a was ﬁltered off as a red solid. Yield: 40 mg, 23%.

Method b. To a solution of [Pt(κ²-Ar)(κ¹-Ar)(OH₂)] (0.23 mmol)

in CH₂Cl₂(15 mL) was added MeC(O)Cl (17 µL, 0.24 mmol). The

solution was stirred until it became a suspension, which was

concentrated to dryness, and CHCl₃(1 mL) was then added. The

resulting suspension was ﬁltered, the solid was stirred with CHCl₃

(2 mL), and this mixture was centrifuged. The decanted solution

was concentrated (1 mL) and ﬁltered. The ﬁltrate was used to isolate

HAr (solution A), and the red solid was identiﬁed as 1a. Yield: 78

1

Dec pt: 300 °C. IR (cm^-1): ν(PtCl) 346. H NMR (400 MHz,

acetone-d₆): δ 9.37-9.34 (m, 1 H, bpy), 8.57-8.51 (m, 3 H, bpy),

8.44-8.38 (m, 2 H, bpy), 7.92-7.88 (m, 1 H, bpy), 7.63-7.59

1

(m, 1 H, bpy), 3.99 (s, 6 H, OMe), 3.96 (s, 3 H, OMe). H NMR

(300 MHz, CDCl₃): δ 9.53-9.51 (m, 1 H, bpy), 8.58-8.56 (m, 1

H, bpy), 8.19-8.12 (m, 2 H, bpy), 8.04-7.97 (m, 2 H, bpy),

7.67-7.61 (m, 1 H, bpy), 7.44-7.39 (m, 1 H, bpy), 4.03 (s, 6 H,

OMe), 3.96 (s, 3 H, OMe). ¹³C{¹H} NMR (100.81 MHz, acetone-

d₆): δ 157.40 (C, bpy), 156.57 (C, bpy), 153.36 (CH, bpy), 149.61

(C, Aryl), 148.44 (CH, bpy), 147.19 (C, Aryl), 143.72 (C, Aryl),

141.30 (CH, bpy), 140.26 (CH, bpy), 128.92 (CH, bpy), 128.20

(CH, bpy), 124.60 (CH, bpy), 124.17 (CH, bpy), 121.40 (C, Aryl),

62.52 (m-OMe), 61.45 (p-OMe). Anal. Calcd for C₂₀H₁₉Cl₃N₄O₇Pt:

C, 32.96; H, 2.75; N, 7.69. Found: C, 32.93; H, 2.60; N, 7.73. Single

crystals were obtained by slow diffusion of Et₂O into a solution of

2a · CH₂Cl₂in CH₂Cl₂.

1

mg, 70%. IR (cm^-1): ν(PtCl) 338, 308, 277. H NMR (400 MHz,

CDCl₃, a:b isomers 1:1): isomer a, δ 4.16 (s, 6 H, OMe), 4.06 (s,

6 H, OMe), 3.87 (s, 6 H, OMe); isomer b, δ 4.14 (s, 6 H, OMe),

Synthesis of [PtBr(K¹-Ar)(cod)] (2b). To a stirred suspension

of 1b (65 mg, 0.06 mmol) in CH₂Cl₂(3 mL) was added cod (31

µL, 0.25 mmol). The resulting solution was concentrated (1 mL),

and hexane (5 mL) was added to give an oil, which was vigorously

stirred. The resulting suspension was ﬁltered and the solid washed

with hexane and air-dried to give 2b as a pale yellow solid. Yield:

(7) Vicente, J.; Arcas, A.; Ga´lvez-Lo´pez, M. D.; Jones, P. G. Organo-

metallics 2004, 23, 3521.

(8) Vicente, J.; Arcas, A.; Galvez-Lopez, M. D.; Julia´-Herna´ndez, F.;

Bautista, D.; Jones, P. G. Organometallics 2008, 27, 1582.

(9) Vicente, J.; Chicote, M. T.; Martin, J.; Jones, P. G.; Fittschen, C.

J. Chem. Soc., Dalton Trans. 1987, 881.

(10) Vicente, J.; Arcas, A.; Ferna´ndez-Herna´ndez, J. M.; Aullon, G.;

Bautista, D. Organometallics 2007, 26, 6155.

(11) Vicente, J.; Arcas, A.; Ga´lvez-Lo´pez, M. D.; Jones, P. G. Orga-

nometallics 2006, 25, 4247.

1

68 mg, 87%. Mp: 218-220 °C. H NMR (300 MHz, CDCl₃): δ

5.83-5.81 (m, 2 H, CH, ²J_PtH) 44 Hz), 5.12-5.10 (m, 2 H, CH,

²J_PtH) 69 Hz), 4.00 (s, 6 H, OMe), 3.89 (s, 3 H, OMe), 2.69-2.51

(m, 4 H, CH₂), 2.34-2.17 (m, 4 H, CH₂). ¹³C{¹H} NMR (75.45

3

2

MHz, CDCl₃): δ 148.81 (m-C, J_PtC) 53 Hz), 145.11 (o-C, J_PtC

2,6-Dinitroaryl Pt(II) and Pt(IV) Complexes

Organometallics, Vol. 28, No. 12, 2009 3503

) 25 Hz), 143.72 (p-C), 125.67 (i-C, ¹J_PtC) 978 Hz), 112.52 (CH,

¹J_PtC) 62 Hz), 93.90 (CH, ¹J_PtC) 165 Hz), 62.25 (m-OMe), 61.06

(p-OMe), 31.67 (CH₂, ²J_PtC) 19 Hz), 28.52 (CH₂, ²J_PtC) 12 Hz).

Anal. Calcd for C₁₇H₂₁BrN₂O₇Pt: C, 31.89; H, 3.31; N, 4.37. Found:

C, 31.51; H, 3.29; N, 4.29.

(s, 6 H, OMe), 3.92 (s, 3 H, OMe), 2.38 (s, 12 H, Me); cis isomer,

δ 7.15-7.09 (m, 6 H, Xy, AB₂system), 4.00 (s, 6 H, OMe), 3.90

(s, 3 H, OMe), 2.47 (s, 6 H, Me), 2.31 (s, 6 H, Me). ¹³C{¹H} NMR

(75.45 MHz, CDCl₃): δ 148.07 (C, Aryl), 146.68 (C, Aryl, J_PtC

)

58 Hz), 143.52 (C, Aryl, J_PC) 12 Hz), 136.39 (s, o-C, Xy), 130.39

(p-C, Xy), 128.05 (m-C, Xy), 125.17 (br, i-C, Xy), 109.41 (C, Aryl),

62.31 (m-OMe), 61.24 (p-OMe), 18.36 (Me). Anal. Calcd for

C₂₇H₂₇BrN₄O₇Pt: C, 40.82; H, 3.43; N, 7.05. Found: C, 41.20; H,

3.56; N, 6.87.

Synthesis of [PtBr(K¹-Ar)(nbd)] (2c). To a stirred suspension

of 1b (51 mg, 0.05 mmol) in CH₂Cl₂(3 mL) was added

2,5-norbornadiene (nbd, 20 µL, 0.20 mmol). The solution was

concentrated (1 mL), and n-hexane (15 mL) was added. The

resulting suspension was ﬁltered, and the solid obtained was washed

with n-hexane and air-dried to give 2c as a pale yellow solid. Yield:

Synthesis of (SP-4-4)-[Pt(K²-Ar)Br(NCMe)] (5a). Acetonitrile

(5.8 µL, 0.11 mmol) was added to a stirred suspension of 1b (48

mg, 0.05 mmol) in CH₂Cl₂(4 mL) to give a red solution, which

was concentrated (1 mL), and Et₂O (10 mL) was added. The

resulting suspension was ﬁltered and the solid washed with Et₂O

and air-dried to give 5a as a red solid. Yield: 36 mg, 70%. Dec pt:

1

57 mg, 95%. Dec pt: 242-249 °C. H NMR (300 MHz, CDCl₃):

2

δ 5.82-5.81 (m, 2 H, CH, J_PtH) 43 Hz), 5.49-5.48 (m, 2 H,

2

CH, J_PtH) 72 Hz), 4.31 (m, 2 H, CH), 3.98 (s, 6 H, OMe), 3.87

(s, 3 H, OMe), 1.70-1.69 (m, 2 H, CH₂, J_PtH) 23 Hz). ¹³C{¹H}

NMR (75.45 MHz, CDCl₃): δ 148.50 (m-C, ³J_PtC) 61 Hz), 144.75

1

174 °C. H NMR (300 MHz, CDCl₃): δ 4.19 (s, 3 H, OMe), 4.08

2

4

(o-C, J_PtC) 27 Hz), 143.77 (p-C, J_PtC) 11 Hz), 126.68 (i-C,

(s, 3 H, OMe), 3.90 (s, 3 H, OMe), 2.66 (s, 3 H Me, J_PtH) 15

¹J_PtC) 1118 Hz), 96.85 (CH, J_PtC) 45 Hz), 76.28 (CH, J_PtC

)

1

Hz). Anal. Calcd for C₁₁H₁₂BrN₃O₇Pt: C, 23.05; H, 2.11; N, 7.33.

Found: C, 23.12; H, 2.08; N, 7.13. Single crystals were obtained

by slow evaporation of a CDCl₃solution of 5a.

3

135 Hz), 71.72 (CH₂, J_PtC) 106 Hz), 62.25 (m-OMe), 61.11 (p-

OMe), 49.84 (CH, ²J_PtC) 49 Hz). Anal. Calcd for C₁₆H₁₇BrN₂O₇Pt:

C, 30.78; H, 2.74; N, 4.49. Found: C, 31.08; H, 2.70; N, 4.49. Single

crystals were obtained by slow diffusion of of Et₂O into a solution

of 2c in CDCl₃.

Synthesis of (SP-4-4)-[Pt(K²-Ar)Br(CNXy)] (5b). To a suspen-

sion of 1b (26 mg, 0.02 mmol) in CH₂Cl₂(4 mL) was added XyNC

(Xy ) 2,6-dimethylphenyl; 6.4 mg, 0.05 mmol). After 48 h the

solution was concentrated (1 mL). Addition of Et₂O (5 mL) gave

a suspension, which was ﬁltered; the solid was washed with Et₂O

and air-dried in vacuo to give 5b as a red solid. Yield: 25 mg,

79%. Mp: 197-200 °C. IR (cm^-1): ν(CtN) 2200. ¹H NMR (400.91

MHz, CDCl₃): δ 7.26-7.22 (m, 1 H, Xy, part A system AB₂),

7.16-7.14 (m, 2 H, Xy, part B system AB₂), 4.14 (s, 3 H, OMe),

4.10 (s, 3 H, OMe), 3.90 (s, 3 H, OMe), 2.52 (s, 6 H, Me). ¹³C{¹H}

NMR (100.81 MHz, CDCl₃): δ 154.91 (C, Aryl), 154.72 (C, Aryl),

144.74 (C, Aryl), 142.93 (C, Aryl), 135.99 (o-C, Xy), 135.42 (br,

CtN), 129.92 (p-C, Xy), 127.93 (m-C, Xy), 126.68 (br, i-C, Xy),

126.52 (C, Aryl), 111.60 (br, i-C Ar), 62.55 (m-OMe), 62.48 (m-

OMe), 61.73 (m-OMe), 18.64 (Me, Xy). Anal. Calcd for

C₁₈H₁₈BrN₃O₇Pt: C, 32.59; H, 2.74; N, 6.33. Found: C, 32.96; H,

2.79; N, 6.20.

Synthesis of [Pt(K²-Ar)(acac-K²O,O)] (3). A suspension of 1b

(65 mg, 0.06 mmol) in CH₂Cl₂(7 mL) was stirred for 14 h with

Tl(acac) (37 mg, 0.12 mmol). The resulting suspension was ﬁltered

through Celite, the ﬁltrate was concentrated (1 mL), and Et₂O (15

mL) was added. The suspension was ﬁltered and the solid washed

with Et₂O and air-dried to give 3 as a dark pink solid. Yield: 31

mg, 47%. Dec pt: 195 °C. IR (cm^-1): ν(Pt-O) 476. ¹H NMR (300

MHz, CDCl₃): δ 5.45 (s, 1 H, CH acac), 4.15 (s, 3 H, OMe), 4.05

(s, 3 H, OMe), 3.88 (s, 3 H, OMe), 2.03 (s, 3 H, Me acac), 1.95 (s,

3 H, Me acac). ¹³C{¹H} NMR (75.45 MHz, CDCl₃): δ 186.09 (CO),

2

184.33(CO, J_PtC) 45 Hz), 154.72 (C, Aryl), 153.83 (C, Aryl),

142.15 (C, Aryl), 136.22 (C, Aryl), 119.31 (C, Aryl), 102.39 (CH

3

acac, J_PtC) 71 Hz), 62.35 (OMe), 62.22 (OMe), 61.56 (OMe),

27.02 (Me, acac), 25.31 (Me acac, ³J_PtC) 65 Hz). Anal. Calcd for

C₁₄H₁₆N₂O₉Pt: C, 30.50; H, 2.93; N, 5.08. Found: C, 30.24; H,

3.00; N, 4.96. Single crystals were obtained by slow diffusion of

n-hexane into a CH₂Cl₂solution of 3.

Synthesis of (SP-4-4)-[Pt(K²-Ar)Br(CO)] (5c). CO was bubbled

through a suspension of 1b (54 mg, 0.05 mmol) in CH₂Cl₂(4 mL)

until it became an orange solution. The solution was concentrated

(1 mL), and Et₂O (15 mL) was added. The resulting suspension

was ﬁltered and the solid washed with Et₂O and air-dried to give

5c as a red solid. The ﬁltrate was concentrated to dryness, and

CH₂Cl₂(1 mL) and hexane (3 mL) were added. The resulting

suspension was ﬁltered and the solid washed with hexane and air-

dried to get a second crop of 5c. Yield: 47 mg, 84%. Mp: 184-186

°C. IR (cm^-1): ν(CO) 2124, 2116 (sh). ¹H NMR (400 MHz, CDCl₃):

Synthesis of [Pt(K¹-Ar)Br(NCMe)₂] (4a). To a suspension of

1b (16 mg, 0.02 mmol) in CH₂Cl₂(1 mL) was added acetonitrile

(32 µL, 0.61 mmol) to give a pale orange solution. After 14 h,

addition of Et₂O (15 mL) gave a suspension. The solid was

separated by ﬁltration, washed with Et₂O, and air-dried to give 4a

as a pale yellow solid. Yield: 12 mg, 67%. ¹H NMR (200.13 MHz,

CDCl₃, trans:cis isomers 2.5:1), δ 4.19 (s, 3 H, OMe 5a), 4.08 (s,

3 H, OMe 5a), 3.98 (s, 6 H, OMe trans), 3.96 (s, 6 H, OMe cis),

3.91 (s, 3 H, OMe trans), 3.90 (s, 3 H, OMe 5a), 3.87 (s, 3 H,

1

δ 4.22 (s, 6 H, OMe), 3.92 (s, 3 H, OMe). H NMR (400 MHz,

4

CDCl₃, -30 °C): δ 4.32 (s, 3 H, OMe), 4.26 (s, 3 H, OMe), 3.93

(s, 3 H, OMe). ¹H NMR (400 MHz, CDCl₃, -50 °C): δ 4.34 (s, 3

H, OMe), 4.28 (s, 3 H, OMe), 3.94 (s, 3 H, OMe). ¹³C{¹H} NMR

(100.81 MHz, CDCl₃): δ 155.98 (C, Aryl, J_PtC) 53 Hz), 152.49

(C, Aryl), 143.60 (C, Aryl), 128.26 (C, Aryl), 62.84 (m-OMe), 62.02

(p-OMe). Anal. Calcd for C₁₀H₉BrN₂O₈Pt: C, 21.44; H, 1.62; N,

5.00. Found: C, 21.61; H, 1.63; N, 4.86.

OMe cis), 2.66 (s, 3 H, Me, 5a, J_PtH) 15 Hz), 2.43 (s, 6 H, Me

trans, ⁴J_PtH) 15 Hz), 2.37 (s, 3 H, Me cis), 2.35 (s, 3 H, Me cis),

2.01 (s, Me, free MeCN). ¹H NMR (200.13 MHz, CDCl₃+ MeCN

(30.4 µL), trans:cis isomers 2.5:1): δ 3.98 (s, 6 H, OMe trans),

3.96 (s, 6 H, OMe cis), 3.92 (s, 3 H, OMe trans), 3.87 (s, 3 H,

OMe cis), 2.44 (s, 6 H, Me trans, ⁴J_PtH) 14 Hz), 2.37 (s, 3 H, Me

cis), 2.35 (s, 3 H, Me cis), 2.01 (s, 3H, Me, free MeCN). Anal.

Calcd for C₁₃H₁₅BrN₄O₇Pt: C, 25.42; H, 2.46; N, 9.12. Found: C,

25.33; H, 2.39; N, 8.95.

Synthesis of [Pt(K¹-Ar)(µ-Br)(η²-EtCtCEt)]₂(6a). 3-Hexyne

(22 µL, 0.19 mmol) was added to a stirred suspension of 1b (51

mg, 0.05 mmol) in CH₂Cl₂(3 mL). The resulting solution was

concentrated (1 mL), and Et₂O (5 mL) was added. The suspension

was ﬁltered and the solid washed with Et₂O and air-dried to give

6a as a pale yellow solid. Yield: 49 mg, 83%. Mp: 152-156 °C.

¹H NMR (400 MHz, CDCl₃): δ 3.97 (s, 6 H, OMe), 3.87 (s, 3 H,

Synthesis of [Pt(K¹-Ar)Br(CNXy)₂] (4b). To a suspension of

1b (52 mg, 0.05 mmol) in CH₂Cl₂(5 mL) was added XyNC (51

mg, 0.39 mmol; Xy ) C₆H₃Me₂-2,6), and the solution was

concentrated to dryness. The residue was triturated with Et₂O (1

mL), and the suspension was ﬁltered to give a solid, which was

washed with Et₂O and air-dried to give 4b as a yellow solid. Yield:

50 mg, 64%. IR (cm^-1): ν(CtN) 2197. ¹H NMR (300 MHz, CDCl₃,

trans:cis isomers 6:1): trans isomer, δ 7.28-7.23 (m, Xy, part A

of the AB₂system), 7.12-7.09 (m, Xy, part B AB₂system,), 3.97

3

OMe), 2.49 (q, 4 H, CH₂, J_HH) 7.3 Hz), 1.28 (t, 6 H, Me, J_HH

) 7.3 Hz). ¹³C{¹H} NMR (75.45 MHz, CDCl₃): δ 147.91 (C, Aryl),

145.92 (C, Aryl), 143.85 (C, Aryl), 106.42 (C, Aryl), 77.66 (s,

CtC), 62.30 (m-OMe), 61.15 (p-OMe), 16.50 (CH₂), 13.40 (Me).

3504 Organometallics, Vol. 28, No. 12, 2009

Vicente et al.

Anal. Calcd for C₃₀H₃₈Br₂N₄O₁₄Pt₂: C, 29.33; H, 3.12; N, 4.56.

Found: C, 29.68; H, 3.20; N, 4.51.

to give 8a as a pale yellow solid. Yield: 53 mg, 89%. Dec pt: 308

°C. IR (cm^-1): ν(PtCl) 310. ¹H NMR (200 MHz, CDCl₃): δ

7.80-7.20 (m, 15 H, PPh₃), 3.76 (s, 3 H, OMe), 3.73 (s, 6 H, OMe),

Synthesis of [Pt(K¹-Ar)(µ-Br)(η²-C₂H₄)]₂(6b). A stream of

ethylene was bubbled at atmospheric pressure into a stirred

suspension of 1b (55 mg, 0.05 mmol) in CH₂Cl₂(3 mL) until a

pale yellow solution had formed. This was concentrated (1 mL),

and n-hexane (10 mL) was added. The suspension was ﬁltered,

and the solid was washed with n-hexane and air-dried to give 6b

as a pale pink-orange solid. Yield: 43 mg, 77%. Mp: 152-154 °C.

¹H NMR (400 MHz, CDCl₃, -30 °C, a:b isomers 4:1): a isomer,

δ 4.68 (s, 8 H, C₂H₄), 4.02 (s, 12 H, OMe), 3.92 (s, 6 H, OMe); b

isomer, δ 4.46 (s, 8 H, C₂H₄), 3.98 (s, 12 H, OMe), 3.85 (s, 6 H,

OMe). ¹³C{¹H} NMR (100.81 MHz, CDCl₃): δ 147.46 (C, Aryl),

146.40 (C, Aryl), 144.39 (p-C, Aryl), 103.77 (C, Aryl), 72.45 (C₂H₄,

¹J_PtC) 191 Hz), 62.37 (m-OMe), 61.23 (p-OMe). Anal. Calcd for

C₂₂H₂₆Br₂N₄O₁₄Pt₂: C, 23.58; H, 2.34; N, 5.00. Found: C, 23.98;

H, 2.36; N, 4.91. Single crystals were obtained by slow diffusion

of n-hexane into a solution of 6b in CDCl₃.

4

3

2.50 (d, 6 H, Me, J_PH) 4 Hz, J_PtH) 38 Hz). ³¹P{¹H} NMR

(162.29 MHz, CDCl₃): δ 14.13 (s, PPh₃, ¹J_PtP) 3634 Hz). ¹³C{¹H}

NMR (50.30 MHz, CDCl₃): δ 147.13 (C, Aryl), 146.43 (C, Aryl),

142.74 (C, Aryl), 135.33-134.15 (m, o-C PPh₃), 130.75 (d, p-C

4

1

PPh₃, J_PC) 1.7 Hz), 128.72 (d, i-C PPh₃, J_PC) 28 Hz), 127.93

3

2

(d, m-C PPh₃, J_PC) 11 Hz), 122.87 (d, i-C, Aryl, J_PC) 8 Hz),

62.02 (m-OMe), 61.10 (p-OMe), 21.25 (d, SMe₂, J_PC) 2 Hz).

3

Anal. Calcd for C₂₉H₃₀ClN₂O₇PSPt: C, 42.89; H, 3.72; N, 3.45; S,

3.95. Found: C, 42.82; H, 3.55; N, 3.43; S, 3.76. Single crystals

were obtained by slow diffusion of n-pentane into a CDCl₃solution

of 8a.

Synthesis of (SP-4-4)-[Pt(K¹-Ar)Cl(PPh₃)(CO)] (8b). A stream

of CO was bubbled through a solution of 6d (52 mg, 0.04 mmol)

in CH₂Cl₂(5 mL) for 7 min. The addition of hexane (10 mL) gave

a suspension. This was ﬁltered and the solid washed with n-hexane

and air-dried to give 8b as a pale yellow solid. Yield: 45 mg, 83%.

1

Dec pt: 315 °C. IR (cm^-1): ν(CO) 2134; ν(PtCl) 328. H NMR

(400 MHz, CDCl₃): δ 7.68-7.31 (m, 15 H, PPh₃), 3.80 (s, 3 H,

OMe), 3.78 (s, 6 H, OMe). ³¹P{¹H} NMR (162.19 MHz, CDCl₃):

1

δ 15.19 (s, PPh₃, J_PtP) 3270 Hz). ¹³C{¹H} NMR (100.81 MHz,

CDCl₃): δ 168.55 (d, CO, ²J_PC) 158 Hz), 148.10 (C, Aryl), 146.40

(C, Aryl), 144.04 (C, Aryl), 134.91 (m, o-C PPh₃), 131.49 (br, p-C

Synthesis of [Pt(K¹-Ar)(µ-Br)(η²-PhCHdCH₂)]₂(6c). To a

stirred suspension of 1b (54 mg, 0.05 mmol) in CH₂Cl₂(4 mL)

was added PhCHdCH₂(23 µL, 0.2 mmol). The resulting solution

was concentrated to dryness, and the solid residue was stirred with

Et₂O (2 mL). The suspension was ﬁltered, and the solid was washed

with Et₂O and air-dried to give 6c as a pale pink solid. To the

ﬁltrate was added n-hexane (2 mL). The resulting suspension was

ﬁltered and the solid washed with hexane and air-dried to get a

second crop of 6c. Yield: 53 mg, 83%. Mp: 151-153 °C. ¹H NMR

3

PPh₃), 129.01 (d, J_PC) 11 Hz), 128.36 (d, m-C PPh₃, J_PC) 9

Hz), 126.22 (d, i-C PPh₃, ¹J_PC) 66 Hz), 114.50 (d, i-C, Aryl, ²J_PC

) 9 Hz), 62.10 (m-OMe), 61.18 (p-OMe). Anal. Calcd for

C₂₈H₂₄ClN₂O₈PPt: C, 43.23; H, 3.11; N, 3.60. Found: C, 42.93; H,

3.10; N, 3.77.

Synthesis of (SP-4-3)-[Pt(K¹-Ar)Cl(PPh₃)(CNXy)] (8c1). To a

stirred suspension of 6d (50 mg, 0.03 mmol) in CH₂Cl₂(3 mL)

was added XyNC (9 mg, 0.07 mmol). The resulting solution was

concentrated to dryness. The crude residue was treated with acetone

(10 mL) to give a pale yellow solution that was reﬂuxed for 4.5 h.

Then, the solution was concentrated (1 mL) and Et₂O (10 mL) was

added. The suspension was ﬁltered and the solid washed with Et₂O

and air-dried to give 8c1 as a pale yellow solid. Yield: 31 mg,

3

(400.91 MHz, CDCl₃): δ 7.54 (d, 2 H, o-H, J_HH) 7.3 Hz), 7.34

3

(d, 1 H, p-H, J_HH) 7.3 Hz), 7.28 (t, 2 H, m-H, J_HH) 7.3 Hz),

6.07 (dd, 1 H, H_c, ³J_{H H}) 7.6 Hz, ³J_HaHc) 14.7 Hz), 5.26 (d, 1 H,

b

c

3

H_a, J_{H H}) 14.7 Hz), 4.63 (d, 1 H, H_b, J_{H H}) 7.6 Hz), 4.02 (s,

3 H, OM^ce), 3.99 (s, 3 H, OMe), 3.92 (s, 3 H, OMe). ¹³C{¹H} NMR

(75.45 MHz, CDCl₃): δ 147.40 (C, Aryl), 147.34 (C, Aryl), 146.92

(C, Aryl), 146.68 (C, Aryl), 144.20 (p-C Ar), 135.94 (C Ph), 130.44

(CH, Ph), 128.85 (CH, Ph), 128.54 (CH, Ph), 103.90 (C, Aryl),

91.20 (CH, Ph, ¹J_PtC) 159 Hz), 62.82 (CH₂), 62.40 (OMe), 62.37

(OMe), 61.25 (OMe). Anal. Calcd for C₃₄H₃₄Br₂N₄O₁₄Pt₂: C, 32.09;

H, 2.69; N, 4.40. Found: C, 31.93; H, 2.88; N, 4.22. Single crystals

of trans-6c · CDCl₃were obtained by slow diffusion of of n-hexane

into a solution of 6c in CDCl₃.

a

b c

1

67%. Mp: 227-230 °C. IR (cm^-1): ν(CN) 2188; ν(PtCl) 334. H

NMR (300 MHz, CDCl₃): δ 7.69-7.62 (m, 6 H, PPh₃), 7.40-7.37

(s, 9 H, PPh₃), 7.12-7.06 (m, 1 H, p-H Xy), 6.93-6.90 (m, 2 H,

m-H Xy), 4.00 (s, 6 H, OMe), 3.89 (s, 3 H, OMe), 1.95 (s, 6 H,

Me). ³¹P{¹H} NMR (121.50 MHz, CDCl₃): δ 16.01 (s, PPh₃, ¹J_PtP

) 2092 MHz). ¹³C{¹H} NMR (75.45 MHz, CDCl₃): δ 147.81 (d,

4

3

m-C, Aryl, J_PC) 7.2 Hz, J_PtC) 44 Hz), 146.83 (d, o-C, Aryl,

³J_PC) 3.3 Hz, J_PtC) 18 Hz), 143.62 (d, p-C, Aryl, J_PC) 1.1

2

5

Synthesis of trans-[Pt(K¹-Ar)Cl(PPh₃)₂] (trans-7). PPh₃(18 mg,

0.07 mmol) was added to a suspension of trans-[Pt(κ¹-Ar)(µ-

Cl)(PPh₃)]₂(6d) (50 mg, 0.03 mmol) in CH₂Cl₂(5 mL). After 19 h,

the resulting solution was concentrated (1 mL) and addition of Et₂O

(10 mL) gave a suspension that was ﬁltered; the solid was washed

with Et₂O and air-dried to give complex trans-7 as a pale yellow

solid. Yield: 66 mg, 99%. Mp: 284-286 °C. IR (cm^-1): ν(PtCl)

Hz), 135.25 (o-C, Xy), 134.59 (d, o-C PPh₃, ²J_PC) 11 Hz, ³J_PtC

)

2

13 Hz), 133.43 (d, i-C, Aryl, J_PC) 122 Hz), 131.07 (p-C PPh₃,

⁴J_PC) 2.2 Hz), 129.12 (p-C, Xy), 129.15 (d, i-C PPh₃, ¹J_PC) 55,

²J_PtC) 20 Hz), 128.55 (d, m-C PPh₃, ³J_PC) 11 Hz), 127.60 (m-C,

3

Xy), 126.46 (br, i-C, Xy, J_PtC) 27 Hz), 62.27 (m-OMe), 61.03

(p-OMe), 17.90 (Me, Xy). Anal. Calcd for C₃₆H₃₃ClN₃O₇PPt: C,

49.07; H, 3.77; N, 4.77. Found: C, 48.67; H, 3.67; N, 4.79. Single

crystals were obtained by slow diffusion of Et₂O into a CDCl₃

solution of 8c1.

1

302. H NMR (400 MHz, CDCl₃): δ 8.00-6.90 (m, 30 H, PPh₃),

3.64 (s, 3 H, OMe), 3.54 (s, 6 H, OMe). ³¹P{¹H} NMR (162.19

1

MHz, CDCl₃): δ 19.21 (s, PPh₃, J_PtP) 2770 Hz). ¹³C{¹H} NMR

Synthesis of [Pt(K¹-Ar)(acac-K²O,O)(PPh₃)] (9). To a solution

of 6d (63 mg, 0.04 mmol) in distilled CH₂Cl₂(10 mL), under a

nitrogen atmosphere, was added Tl(acac) (26 mg, 0.09 mmol), and

the suspension was stirred for 19 h. The resulting suspension was

ﬁltered though Celite, the ﬁltrate was concentrated (1 mL), Et₂O

(20 mL) was added, and the suspension was ﬁltered. The solid was

washed with Et₂O and air-dried to give 9 as a pale yellow solid.

Yield: 50 mg, 73%. Mp: 266-267 °C. IR (Nujol, cm^-1): ν(PtO)

452. ¹H NMR (400.91 MHz, CDCl₃): δ 7.56-7.31 (m, 15 H, PPh₃),

5.40 (s, 1 H, CH acac), 3.77 (s, 3 H, OMe), 3.74 (s, 6 H, OMe),

1.95 (s, 3 H, Me acac), 1.55 (s, 3 H, Me acac). ³¹P{¹H} NMR

(162.29 MHz, CDCl₃): δ 3.40 (s, PPh₃, ¹J_PtP) 4329 Hz). ¹³C{¹H}

(100.81 MHz, CDCl₃): δ 147.85 (C, Aryl, J_PtC) 63 Hz), 145.48

(C, Aryl), 142.20 (C, Aryl), 135.78 (br, o-C PPh₃), 133.22 (br, i-C

PPh₃), 130.90 (br, p-C PPh₃), 128.18 (br, m-C PPh₃), 127.52 (t,

2

i-C, Aryl, J_PtP) 9 Hz), 61.84 (m-OMe), 61.17 (p-OMe). Anal.

Calcd for C₄₅H₃₉ClN₂O₇P₂Pt: C, 53.39; H, 3.88; N, 2.77. Found:

C, 53.01; H, 4.24; N, 2.63. Single crystals were obtained by slow

diffusion of Et₂O into a CDCl₃solution of trans-7.

Synthesis of (SP-4-4)-[Pt(K¹-Ar)Cl(PPh₃)(SMe₂)] (8a). To a

suspension of 6d (55 mg, 0.04 mmol) in CH₂Cl₂(3 mL) was added

SMe₂(5.5 µL, 0.08 mmol). The resulting solution was concentrated

(1 mL), and n-hexane (15 mL) was added. The resulting suspension

was ﬁltered, and the solid was washed with n-hexane and air-dried

2,6-Dinitroaryl Pt(II) and Pt(IV) Complexes

Organometallics, Vol. 28, No. 12, 2009 3505

3

NMR (100.81 MHz, CDCl₃): δ 185.13 (d, C acac, J_PtC) 2 Hz),

183.83 (C acac), 148.14 (C, Aryl), 146.40 (C, Aryl), 142.58 (C,

Aryl), 134.37 (br, o-C PPh₃), 130.58 (p-C PPh₃), 128.49 (d, i-C

PPh₃, ¹J_PC) 65 Hz), 127.79 (d, m-C PPh₃, ³J_PC) 11 Hz), 116.42

(o-C, Aryl cation), 144.01 (p-C, Aryl cation), 143.35 (CH, bpy),

143.24 (CH, bpy), 141.47 (p-C Ar), 135.85-135.61 (m, o-C PPh₃),

133.10 (br, p-C PPh₃cation), 130.31 (br, p-C PPh₃anion), 129.57

3

(d, m-C PPh₃cation, J_PC) 11.4 Hz), 127.81 (CH, bpy), 127.58

2

(d, m-C PPh₃anion, ³J_PC) 10 Hz), 127.56 (CH, bpy), 127.04 (CH,

bpy), 126.86 (CH, bpy), 126.08 (d, i-C PPh₃cation, ¹J_PC) 61 Hz),

124.11 (d, i-C, Aryl anion, ²J_PC) 6 Hz), 121.22 (d, i-C, Aryl cation,

²J_PC) 12 Hz), 62.12 (m-OMe cation), 61.89 (m-OMe anion), 61.18

(p-OMe cation), 61.00 (p-OMe anion). Anal. Calcd for

C₆₄H₅₆Cl₂N₆O₁₄P₂Pt₂: C, 46.41; H, 3.41; N, 5.07. Found: C, 46.01;

H, 3.46; N, 4.89. Single crystals were obtained by slow diffusion

of Et₂O into a CDCl₃/CHCl₃solution of 11 · 10.

(d, i-C, Aryl, J_PC) 12 Hz), 101.59 (CH acac), 61.92 (m-OMe),

61.06 (p-OMe), 27.20 (d, Me acac, ⁴J_PC) 7 Hz), 27.00 (Me, acac).

Anal. Calcd for C₃₂H₃₁N₂O₉PPt: C, 47.24; H, 3.84; N, 3.44. Found:

C, 47.06; H, 3.46; N, 3.78. Single crystals were obtained by slow

diffusion of Et₂O into a CDCl₃solution of 9.

Synthesis of cis-(PPN)[Pt(K¹-Ar)Cl₂(PPh₃)] (PPN · 10). To a

stirred suspension of 6d (53 mg, 0.04 mmol) in CH₂Cl₂(5 mL)

was added PPNCl (41 mg, 0.07 mmol). After 24 h the resulting

solution was concentrated (1 mL) and Et₂O (10 mL) was added.

The suspension was ﬁltered and the solid washed with Et₂O and

air-dried to give PPN · 10 as a pale yellow solid. Yield: 88 mg,

Synthesis of (OC-6-32)-[Pt(K²-Ar)₂Cl₂] (12). A solution of cis-

[Pt(κ²-Ar)(κ¹-Ar)(OH₂)] (0.07 mmol) in CH₂Cl₂was concentrated

to dryness, and CHCl₃(2 mL) and PhICl₂(26 mg, 0.10 mmol)

were then added. The resulting yellow solution was stirred for 15

min and then concentrated (1 mL). Et₂O (10 mL) was added, and

the solid was ﬁltered off, washed with Et₂O, and air-dried, to give

12 as a yellow solid. Yield: 52 mg, 96%. Dec pt: 200 °C. IR (cm^-1):

95%. Mp: 247-249 °C. IR (cm^-1): ν(PtCl) 305, 281. H NMR

1

(400.91 MHz, CDCl₃): δ 8.11-8.93 (m, 45 H, Ph), 3.69 (s, 3 H,

OMe), 3.66 (s, 6 H, OMe). ³¹P{¹H} NMR (162.29 MHz, CDCl₃):

δ 21.25 (s, PPN), 9.15 (s, PPh₃, J_PtP) 4283 Hz). ¹³C{¹H} NMR

1

(75.45 MHz, CDCl₃): δ 147.07 (o-C, Aryl), 146.19 (m-C, Aryl),

141.17 (p-C, Aryl), 136.08 (d, o-C PPh₃, J_PC) 11 Hz),

ν(PtCl) 366, 316. H NMR (300 MHz, CDCl₃): δ 4.30 (s, 3 H,

2

OMe), 4.21 (s, 3 H, OMe), 4.16 (s, 3 H, OMe), 4.13 (s, 3 H, OMe),

3.98 (s, 3 H, OMe), 3.92 (s, 3 H, OMe). ¹³C{¹H} NMR (75.45

MHz, CDCl₃): δ 156.54 (s, C_qAr), 156.05 (s, C_qAr), 156.02 (s,

C_qAr), 154.04 (s, C_qAr), 145.07 (s, C_qAr), 144.44 (s, C_qAr),

143.76 (s, C_qAr), 142.59 (s, C_qAr), 135.67 (s, C_qAr), 133.43 (s,

C_qAr), 115.66 (s, C_qAr), 103.82 (s, C_qAr), 63.26 (s, OMe), 62.96

(s, OMe), 62.87 (s, OMe), 62.84 (s, OMe), 62.36 (s, OMe), 62.11

(s, OMe). Anal. Calcd for C₁₈H₁₈Cl₂N₄O₁₄Pt: C, 27.70; H, 2.32;

N, 7.18. Found: C, 27.55; H, 2.43; N, 7.27. Single crystals were

obtained by slow diffusion of Et₂O into an CH₂Cl₂solution of 12.

Synthesis of (OC-6-22)-[Pt(K²-Ar)₂Cl₂] (13). To a solution of

trans-[Pt(κ²-Ar)(κ²-Ar)(CO)] (55 mg, 0.07 mmol) in CHCl₃(2 mL)

was added a saturated solution of Cl₂in CCl₄(0.5 mL). The solution

was stirred for 20 min, and n-pentane (3 mL) was added. The

suspension was ﬁltered, and the solid was washed with n-pentane

to give complex 13 as an orange solid. Yield: 26 mg, 47%. Dec pt:

181 °C. IR (cm^-1): ν(PtCl) 377, 365. ¹H NMR (300 MHz, CDCl₃):

δ 4.28 (s, 6 H, OMe), 4.16 (s, 6 H, OMe), 3.94 (s, 6 H, OMe).

Anal. Calcd for C₁₈H₁₈Cl₂N₄O₁₄Pt: C, 27.70; H, 2.32; N, 7.18.

Found: C, 27.70; H, 2.26; N, 6.99. Single crystals were obtained

by slow diffusion of n-hexane into an Me₂CO solution of 13.

Synthesis of fac-[Pt(K²-Ar)Cl₃(PPh₃)] (14). To a suspension of

trans-6d (98 mg, 0.07 mmol) in CH₂Cl₂(6 mL) was added PhICl₂

(59 mg, 0.22 mmol). After 6 h the orange solution was concentrated

(1 mL), and Et₂O (10 mL) was added. The resulting suspension

was ﬁltered, and the solid was washed with Et₂O and air-dried to

give 14 as an orange solid. Yield: 103 mg, 97%. Dec pt: 208 °C.

IR (cm^-1): ν(PtCl) 374, 307, 293. ¹H NMR (300 MHz, CDCl₃): δ

7.72-7.65 (m, 6H, PPh₃), 7.59-7.52 (m, 3 H, PPh₃), 7.43-7.37

(m, 6H, PPh₃), 4.15 (s, 3 H, OMe), 3.96 (s, 3 H, OMe), 3.87 (s, 3

H, OMe). ³¹P{¹H} NMR (81.01 MHz, CDCl₃): δ 5.95 (s, PPh₃,

¹J_PtP) 2122 Hz). Anal. Calcd for C₂₇H₂₄Cl₃N₂O₇PPt: C, 39.51; H,

2.95; N, 3.41. Found: C, 39.12; H, 2.92; N, 3.44.

133.96-133.92 (m, p-C PPN), 132.13-131.90 (m, m-C PPN),

129.90 (br, p-C PPh₃), 129.75-129.50 (m, o-C PPN), 127.36 (d,

m-C PPh₃, J_PC) 11 Hz), 126.85 (dd, i-C PPN, J_PC) 108 Hz,

³J_PC) 2 Hz), 125.17 (d, i-C, Aryl, ²J_PC) 7 Hz), 61.77 (m-OMe),

60.94 (p-OMe). Anal. Calcd for C₆₃H₅₄Cl₂N₃O₇P₃Pt: C, 57.15; H,

4.11; N, 3.17. Found: C, 57.04; H, 4.08; N, 3.10.

3

1

Synthesis of [Pt(K¹-Ar)(bpy)(PPh₃)]Cl (11 · Cl). To a suspension

of 6d (14 mg, 0.01 mmol) in CH₂Cl₂was added bpy (6 mg, 0.04

mmol). The resulting suspension was stirred for 24 h and then was

concentrated to dryness. The residue was stirred with Et₂O (10 mL),

the suspension was ﬁltered, and the solid was washed with Et₂O

and air-dried to give 11 · Cl as a pale yellow solid. Yield: 15 mg,

92%. Dec pt: 170 °C. ∆_M) 115 Ω^-1cm²mol^-1. ¹H NMR (400.91

MHz, CDCl₃): δ 9.69-9.64 (m, 2 H, bpy), 8.53-8.48 (m, 1 H,

bpy), 8.44-8.40 (m, 1 H, bpy), 8.03-8.00 (m, 1 H, bpy), 7.95-7.90

(m, 4 H, PPh₃), 7.67-7.54 (m, 9 H, PPh₃+ bpy), 7.12-7.03 (m,

4 H, PPh₃+ bpy), 7.00-6.96 (m, 1 H, bpy), 3.84 (s, 3 H, OMe),

3.79 (s, 6 H, OMe). ³¹P{¹H} NMR (162.29 MHz, CDCl₃): δ 11.34

1

(s, PPh₃, J_PtP) 3750 Hz). ¹³C{¹H} NMR (100.81 MHz, CDCl₃):

3

δ 157.00 (C, bpy), 156.08 (d, C bpy, J_PC) 1.5 Hz), 150.53 (d,

3

CH bpy, J_PC) 3 Hz), 149.79 (CH, bpy), 148.00 (m-C, Aryl),

146.06 (o-C, Aryl), 144.03 (p-C, Aryl), 142.78 (CH, bpy), 142.73

(CH, bpy), 135.58 (d, o-C, PPh₃, ²J_PC) 12 Hz), 133.14 (p-C PPh₃),

3

129.57 (d, m-C PPh₃, J_PC) 11.5 Hz), 127.71 (CH, bpy), 127.30

(CH, bpy), 126.96 (CH, bpy), 126.79 (CH, bpy), 125.85 (d, i-C

1

2

PPh₃, J_PC) 61 Hz), 120.94 (d, i-C, Aryl, J_PC) 12 Hz), 62.11

(m-OMe), 61.14 (p-OMe). Anal. Calcd for C₃₇H₃₂ClN₄O₇PPt: C,

49.04; H, 3.56; N, 6.18. Found: C, 48.70; H, 3.46; N, 6.21.

Synthesisof[Pt(K¹-Ar)(bpy)(PPh₃)][Pt(K¹-Ar)Cl₂(PPh₃)](11 · 10).

To a stirred suspension of 6d (61 mg, 0.04 mmol) in CH₂Cl₂(5

mL) was added bpy (6 mg, 0.04 mmol). After 24 h of stirring, the

resulting solution was concentrated (1 mL) and Et₂O (10 mL) was

added. The suspension was ﬁltered, and the solid was washed with

Et₂O and air-dried to give 11 · 10 as a pale yellow solid. Yield: 59

mg, 89%. Mp: 195-197 °C. Λ_M) 79 Ω^-1cm²mol^-1. IR (Nujol,

Synthesis of [Pt(K²-Ar)₂(OH₂)₂](ClO₄)₂(15). A mixture of 12

(201 mg, 0.26 mmol) and AgClO₄(124 mg, 0.60 mmol) in CH₂Cl₂

(5 mL) was stirred (protected from daylight) for 12 h. The resulting

suspension was ﬁltered, and the solution was concentrated (1 mL).

Addition of Et₂O (10 mL) gave a suspension, which was ﬁltered.

The solid was washed with Et₂O and air-dried to give 15 · Et₂O as

an orange solid. Yield: 207 mg, 89%. Dec pt: 138 °C. Λ_M(acetone,

4.8 × 10^-4M) ) 164 Ω^-1cm²mol^-1. IR (cm^-1): ν(OH)

3641-3605. ¹H NMR (400 MHz, CDCl₃, a:b isomers 4:1): isomer

a, δ 4.35 (s, 3 H, OMe), 4.33 (s, 3 H, OMe), 4.22 (s, 3 H, OMe),

4.16 (s, 3 H, OMe), 3.99 (s, 3 H, OMe), 3.93 (s, 3 H, OMe); isomer

b, δ 4.32 (s, 3 H, OMe), 4.21 (s, 3 H, OMe), 4.20 (s, 3 H, OMe),

1

cm^-1): ν(PtCl) 303, 281. H NMR (400 MHz, CDCl₃): δ 9.42 (d,

1 H, bpy, ³J_HH) 8 Hz), 9.36 (d, 1 H, bpy, ³J_HH) 8 Hz), 8.55-8.48

(m, 2 H, bpy), 8.03-7.92 (m, 9 H, PPh₃+ bpy), 7.66-7.54 (m, 9

H, PPh₃+ bpy), 7.38-7.28 (m, 7 H, PPh₃), 7.13-6.91 (m, 9 H,

PPh₃+ bpy), 3.83 (s, 3H, OMe), 3.79 (s, 6 H, OMe), 3.71 (s, 3 H,

OMe), 3.69 (s, 6 H, OMe). ³¹P{¹H} NMR (162.29 MHz, CDCl₃):

δ 11.51 (s, PPh₃cation, ¹J_PPt) 3750 Hz), 8.64 (s, PPh₃anion, ¹J_PPt

) 4292 Hz). ¹³C{¹H} NMR (100.81 MHz, CDCl₃): δ 156.85 (d,

3

bpy, J_PC) 1.4 Hz), 156.10 (d, bpy, J_PC) 1.4 Hz), 150.32 (d,

CH bpy, J_PC) 2.6 Hz), 149.55 (CH, bpy), 147.97 (m-C, Aryl

cation), 146.92 (o-C, Aryl anion), 146.45 (m-C, Aryl anion), 146.14

1

4.01 (s, 3 H, OMe), 3.94 (s, 3 H, OMe). H NMR (400 MHz,

CDCl₃, -50 °C): δ 7.87 (br, 4 H, H₂O), 4.38 (s, 3 H, OMe), 4.32

3506 Organometallics, Vol. 28, No. 12, 2009

Vicente et al.

(s, 3 H, OMe), 4.27 (s, 3 H, OMe), 4.19 (s, 3 H, OMe), 3.93 (s, 3

H, OMe), 3.86 (s, 3 H, OMe). Both spectra show resonances at

3.50 (q, 4H, CH₂) and 1.20 (t, 6 H, Me) due to 1equiv of Et₂O.

Anal. Calcd for 15 · Et₂O, C₂₂H₃₂Cl₂N₄O₂₅Pt: C, 25.94; H, 3.17; N,

5.50. Found: C, 26.11; H, 3.03; N, 5.89.

Scheme 1

Synthesis of cis-[Pt(K²-Ar)(K¹-Ar)(AsPh₃)] (16). To a suspen-

sion of 12 (81 mg, 0.10 mmol) in CH₂Cl₂(5 mL) was added AsPh₃

(64 mg, 0.21 mmol). The resulting red solution was concentrated

(2 mL), and EtOH was added. After 15 min, the solid was ﬁltered

and the solid washed with EtOH. The ﬁltrate was concentrated,

and ethanol was added. After 15 min, the resulting precipitate was

ﬁltered off, washed with EtOH, and air-dried, to give 16 as a orange

solid. Yield: 33 mg, 29%. Mp: 213-217 °C. ¹H NMR (300 MHz,

CDCl₃): δ 7.52-7.29 (m, 15 H, Ph), 4.04 (s, 3 H, OMe), 4.00 (s,

3 H, OMe), 3.85 (s, 3 H, OMe), 3.84 (s, 3 H, OMe), 3.73 (s, 3 H,

OMe). Anal. Calcd for C₃₆H₃₃AsN₄O₁₄Pt: C, 42.57; H, 3.27; N,

5.52. Found: C, 42.46; H, 3.27; N, 5.44. Single crystals were

obtained by slow diffusion of n-hexane into a solution of 16 in

CDCl₃.

Synthesis of cis-(AsPh₃OH)[Pt(K²-Ar)(K¹-Ar)Cl] (17). To a

suspension of 12 (81 mg, 0.10 mmol) in CH₂Cl₂(2 mL) was added

AsPh₃(32 mg, 0.10 mmol). The resulting suspension was ﬁltered

and the ﬁltrate concentrated (1 mL). Addition of Et₂O (3 mL) gave

a suspension, which was ﬁltered; the solid was washed with Et₂O

and air-dried to give 17 as a red solid. Yield: 70 mg, 62%. Mp:

163-170 °C. Λ_M(acetone, 5.6 × 10^-4M) ) 79 Ω^-1cm²mol^-1

.

IR (cm^-1): ν(PtCl) 293. ¹H NMR (300 MHz, CDCl₃): δ 7.81-7.63

(m, 16 H, HOAsPh₃), 3.98 (s, 9 H, OMe), 3.93 (s, 3 H, OMe),

3.88 (s, 3 H, OMe), 3.82 (s, 3 H, OMe). ¹³C{¹H} NMR (75.45

MHz, CDCl₃): δ 154.21 (m-C, κ²-Ar), 153.41 (m-C, κ²-Ar), 148.89

(o-C, κ²-Ar), 147.98 (o-C, κ²-Ar), 146.65 (m-C, κ¹-Ar), 142.89 (p-

C, Ar), 141.93 (p-C, Ar), 138.02 (o-C, κ²-Ar), 134.80 (p-C, Ph),

132.12 (o-C, Ph), 130.62 (m-C, Ph), 124.07 (i-C, Ar), 124.02 (i-C,

Ph), 111.36 (i-C, Ar), 62.20 (m-OMe, κ²-Ar), 62.01 (m-OMe, κ¹-

Ar), 61.92 (m-OMe, κ²-Ar), 61.19 (p-OMe), 61.13 (p-OMe). Anal.

Calcd for C₃₆H₃₄AsClN₄O₁₅Pt: C, 40.48; H, 3.21; N, 5.25. Found:

C, 40.14; H, 3.11; N, 5.18. Crystals of 17 suitable for X-ray

diffraction studies were obtained by slow diffusion of Et₂O into an

CDCl₃/Me₂CO solution of 17.

11 · 10 · 2CHCl₃, and -0.006(4) for 17; the structure of 11 · 10 ·

2CHCl₃is pseudosymmetric, the anion and cation being related

via a pseudoinversion center. Compounds 3 and 5a were nonmero-

hedrally twinned, in both cases by 180° rotation about the x axis.

The scale factor for the minor component was reﬁned to 0.104(1)

and 0.318(1), respectively. Reﬂections cannot be counted reliably

for these twins; the detwinning involves merging of all equivalent

reﬂections. Compound 8c was pseudomerohedrally twinned by

rotation about a metrically orthorhombic pseudocell (twin matrix

100/0-10/-10-1); the scale factor was 0.373(1).

Results and Discussion

X-ray Structure Determinations. Intensities were registered at

low temperature on a Bruker SMART 1000 CCD diffractometer

using monochromated Mo KR radiation (λ ) 0.710 73 Å).

Absorption corrections were based on multiscans (program SAD-

ABS). Structures were reﬁned anisotropically using SHELXL-97.¹²

Hydrogen atoms were included using rigid methyl groups or a riding

model, except for H atoms of coordinated double bonds, which

were reﬁned freely but with C-H distance restraints (for trans-6b

these hydrogens are indistinct). The OH hydrogen of 17 was located

in a difference synthesis but was reﬁned as a rigid group allowed

to rotate. Special features and exceptions: Compound HAr was

measured on a Siemens P4 diffractometer. For 2a · CH₂Cl₂, 2c,

trans-6c · CDCl₃, and 16 · CDCl₃, absorption corrections were based

on indexed faces. Compound 12 was measured on a Siemens P4

diffractometer, and the absorption correction was based on ψ-scans.

Compound 13 was measured on a Bruker SMART APEX CCD

diffractometer. In this compound the relatively high electron density

near the palladium atom can be ascribed to absorption errors (thin

needle). Some disorder was observed as follows: 8a, a single

signiﬁcant difference peak of 1.5 e Å^-3near the sulfur atom may

indicate a slight disorder of the Me₂S ligand; trans-7 · Et₂O, the

ether molecule is poorly resolved; 8c, isonitrile H atoms were not

located and are probably disordered; 9, methyl H at C1 are

disordered; 11 · 10 · 2CHCl₃, solvent is not well-resolved; 12, C18

and C19 are disordered over two sites; 16 · CDCl₃, solvent is

disordered over two sites with occupation ratio ca. 7:1. Flack

parameters were reﬁned to 0.010(8) for 8c, 0.056(4) for

Synthesis of Mono(nitroaryl) Pt(II) Complexes [Pt₂(K²-

Ar)₂(µ-X)₂] by Protonolysis. As mentioned in the Introduction,

transmetalation reactions from nitroaryl Hg(II) complexes to

Pt(II) give only bis(nitroaryl) Pt(II) complexes, irrespective of

reaction conditions.^7,13Nevertheless, we have recently found

that these diaryl Pt(II) complexes can transmetalate one aryl

group to Hg, affording the ﬁrst mono(nitroaryl) Pt(II) complexes,

[Pt₂(κ¹-Ar)₂(µ-X)(µ-Y)(PPh₃)₂] (X ) Y ) Cl (trans-2d), OH;

X ) AcO, Y ) OH).⁸However, although they can be used to

prepare other mono(nitroaryl) derivatives, as we will show in

this article, the presence of PPh₃leaves only two coordination

positions available for substitution at platinum.

In the search for a more useful starting material for the

preparation of mono(nitroaryl) derivatives, we attempted the

addition of hydrochloric acid to a CH₂Cl₂solution of [Pt(κ²-

Ar)(κ¹-Ar)(OH₂)] (1:1),⁷which led to a 1:1 mixture of cis- and

trans-[Pt₂(κ²-Ar)₂(µ-Cl)₂] (1a; Scheme 1). This method has been

used previously to prepare Pd or Pt (M) complexes (1) [M]Ar′

(Ar′ ) perhaloaryl group) from [M]Ar′₂,^14,15(2) [M]Ar′_n(n )

(13) Vicente, J.; Chicote, M. T.; Martin, J.; Jones, P. G.; Fittschen, C.;

Sheldrick, G. M. J. Chem. Soc., Dalton Trans. 1986, 2215.

(14) Belluco, U.; Giustiniani, M.; Graziani, M. J. Am. Chem. Soc. 1967,

89, 6494. Romeo, R.; Minniti, D.; Lanza, S.; Uguagliati, P.; Belluco, U.

Inorg. Chem. 1978, 17, 2813. Belluco, U.; Michelin, R. A.; Uguagliati, P.;

Crociani, B. J. Organomet. Chem. 1983, 250, 565. Romeo, R.; Plutino,

M. R.; Elding, L. I. Inorg. Chem. 1997, 36, 5909. Casas, J. M.; Diosdado,

B. E.; Fornie´s, J.; Mart´ın, A.; Rueda, A. J.; Orpen, A. G. Inorg. Chem.

2008, 47, 8767.

(12) Sheldrick, G. M. Acta Crystallogr., Sect. A 2008, 64, 112.

2,6-Dinitroaryl Pt(II) and Pt(IV) Complexes

Organometallics, Vol. 28, No. 12, 2009 3507

Scheme 2

Scheme 3

1-3)¹⁶from [M]Ar′₄,(3) [M]₂Ar′₃from [M]₂Ar′₄,¹⁵and (5)

[M]₆Ar′₄from [M]₃Ar′₄.¹⁷

However, a better yield of 1a (70 vs 23%) was obtained by

reacting [Pt(κ²-Ar)(κ¹-Ar)(OH₂)] with MeCOCl (1:1) in the

presence of atmospheric moisture. Probably, the slow production

of HCl prevents formation of other products. The byproduct,

HAr, could also be isolated and characterized by spectroscopy

and by an X-ray diffraction study. The synthesis of HAr was

reported long ago by reaction of 3,5,6-trinitroveratrole with

KOH in MeOH.¹⁸Similarly, [Pt(κ²-Ar)(κ¹-Ar)(OH₂)] reacts with

MeC(O)Br to give a 1:1 mixture of cis- and trans-[Pt₂(κ²-Ar)₂(µ-

Br)₂] (1b). This synthetic approach (using HX or MeC(O)X as

a source of HX) to prepare monocarbyl from dicarbyl complexes

has been reported while we were preparing this paper.¹⁹

Complexes 1 are stable at room temperature in the solid state

and in CHCl₃or CH₂Cl₂solutions, but in acetone they

decompose slowly into unidentiﬁed compounds.

complex (SP-4-4)-[Pt(κ²-Ar)Br(NCMe)] (5a) (2.5:1:1.9; Scheme

3), and MeCN, consistent with the observation that addition of

MeCN is required to isolate pure 4a in CHCl₃. This process

probably occurs by coordination of the nitro group from the

trans isomer, establishing the equilibrium trans-4a a 5a +

MeCN. Indeed, the signals corresponding to 5a in the ¹H NMR

spectrum of this mixture do not appear when CD₃CN is added.

The alternative transformation of cis-4a into the (SP-4-2)-5a

isomer and MeCN is prevented by the mutual hindrance of the

uncoordinated NO₂group and the Br ligand. Trans- and cis-4a

are the ﬁrst reported [Pt(R)X(NCR′)₂] (R, R′ ) hydrocarbyl, X

) halogen) complexes. The reaction of 1b with MeCN (MeCN:

Pt ) 1) in CH₂Cl₂gave 5a. Because of the insolubility of 1b,

it is reasonable to assume that cis-4a is also the ﬁrst product of

this reaction and that its isomerization into trans-4a followed

by O-coordination of the aryl ligand to afford 5a and MeCN

fully converts 1b into 5a.

Similar results have been obtained by reacting 1b with the

isocyanide XyNC (Xy ) 2,6-Me₂C₆H₄) or CO. Thus, a 6:1

mixture of trans-/cis-[Pt(κ¹-Ar)Br(CNXy)₂] (4b; Scheme 2) was

obtained in the reaction of 1b with XyNC (L:Pt ) 2 or 4) at

room temperature or in reﬂuxing acetone (XyNC:Pt ) 2). The

6:1 mixture remained unchanged after heating in a CH₂Cl₂

solution at 100 °C in a Carius tube. The XyNC:Pt ) 1 reaction

in CH₂Cl₂at room temperature gave also the 6:1 mixture along

with other unidentiﬁed products, but this changed slowly, giving

after 48 h pure complex (SP-4-4)-[Pt(κ²-Ar)Br(CNXy)] (5b).

After CO was bubbled for a few minutes through a CH₂Cl₂

suspension of 1b at room temperature, (SP-4-4)-[Pt(κ²-Ar)-

Br(CO)] (5c) was obtained (Scheme 2). This complex is stable

in the solid state and in solution.

Reactivity of [Pt₂(K²-Ar)₂(µ-X)₂]. Complexes 1 react with

neutral bidentate ligands to give [Pt(κ¹-Ar)X(L^∧L)] (X ) Cl,

L^∧L ) bpy (2a); X ) Br, L^∧L ) cod (2b), nbd (2c); Scheme

1) or 1b with Tl(acac) (1:2) to afford [Pt(κ²-Ar)(acac)] (3).

The room-temperature reaction with a large excess of MeCN

(MeCN:Pt ) 20) led to a 2.5:1 mixture of trans- and cis-[Pt(κ¹-

Ar)Br(NCMe)₂] (4a; Scheme 2). This reaction gives ﬁrst cis-

4a, the kinetic product expected in accordance with the strongest

trans effect of the aryl ligand,²⁰which slowly and partially

transforms into trans-4a, reaching the equilibrium trans/cis )

2.5 after 10 h. The isomerization is favored in the presence of

MeCN, because this assists the formation of the required ﬁve-

coordinate transition state.^11,21The lower stability of the cis

isomer could be attributable to the greater steric hindrance

between the anionic ligands. When 4a is dissolved in CDCl₃, a

mixture is obtained containing trans- and cis-4a, the new

(15) Fornie´s, J.; Fortun˜o, C.; Navarro, R.; Mart´ınez, F.; Welch, A. J. J.

Organomet. Chem. 1990, 394, 643.

(16) Uso´n, R.; Fornie´s, J.; Toma´s, M.; Ara, I.; Menjo´n, B. J. Organomet.

Chem. 1987, 336, 129. Uso´n, R.; Fornie´s, J.; Martinez, F.; Toma´s, M.;

Reoyo, I. Organometallics 1983, 2, 1386. Uso´n, R.; Fornie´s, J.; Toma´s,

M.; Fandos, R. J. Organomet. Chem. 1984, 263, 253.

(17) Ara, I.; Fornie´s, J.; Fortun˜o, C.; Iba´n˜ez, S.; Mart´ın, A.; Mastrorilli,

P.; Gallo, V. Inorg. Chem. 2008, 47, 9069.

(18) Pollecoff, F.; Robinson, R. J. Chem. Soc., Trans. 1918, 645.

(19) Sivaramakrishna, A.; Su, H.; Moss, J. R. Dalton Trans. 2008, 2228.

(20) Chval, Z.; Sip, M.; Burda, J. V. J. Comput. Chem. 2008, 29, 2370.

(21) Favez, R.; Roulet, R.; Pinkerton, A. A.; Schwarzenbach, D. Inorg.

Chem. 1980, 19, 1356.

The complexes trans-/cis-1b react with 3-hexyne, ethylene,

or styrene (1:4), affording one, two (1:4), or four (one major)

isomers, respectively, of [Pt(κ¹-Ar)(µ-Br)(η²-L)]₂(L ) 3-hexyne

(6a), ethylene (6b), styrene (6c); Scheme 3), which result from

the cleavage of the O-Pt bond. Reaction of 1b with PhCtCH

or MeO₂CCtCCO₂Me gave complex mixtures of unidentiﬁed

3508 Organometallics, Vol. 28, No. 12, 2009

Vicente et al.

Scheme 4

products. Single crystals of the trans isomers 6b,c could be

obtained and studied by X-ray diffraction (see Crystal Struc-

tures). Probably, this is also the geometry of the only isomer

obtained of 6a and is the most abundant of 6b,c. The formation

of 6 is not the result that would be expected from a consideration

of the greater trans effect of the aryl ligand compared to that of

the bromo ligand.²⁰Furthermore, the products lack the stability

of the chelating κ²-Ar ligand. Probably, formation of products

resulting from bridge cleavage is prevented (1) if η²-L coordi-

nates trans to Ar, by the transphobia (τ)^10,11,22,23between the

two trans carbon donor ligands, which is greater than that

between a carbon and Br ligand, i.e. τ(aryl/η²-L) . τ(aryl/Br),

or (2) if η²-L coordinates trans to O, by the hindrance of the

uncoordinated NO₂group of the κ²-Ar ligand and η²-L, which

is not as important when L ) MeCN, XyNC, CO. PPh₃also

behaves toward 1a (Pt:P ) 1:1) as a bulky ligand, giving trans-

[Pt(κ¹-Ar)(µ-Cl)(PPh₃)]₂(trans-6d).⁸However, because of the

insolubility of 1b, trans- and cis-[Pt(κ¹-Ar)Cl(PPh₃)₂] (7) and

minor amounts of other unidentiﬁed complexes were detected.

Although cis-7 could not be isolated, NMR data prove its

presence in the reaction mixture (¹H NMR: δ 3.78, s, 6 H,

1

m-OMe; 3.71 (s, 3 H, p-OMe); ³¹P NMR: δ 19.1 (d), J_PtP

)

2136 Hz, ²J_PP) 19 Hz; 12.0 (d), ¹J_PtP) 3991 Hz; see below).

However, trans-7 could be obtained quantitatively by reacting

trans-6d with PPh₃(see below).

Synthesis of Mono(nitroaryl) Pt(II) Complexes from

trans-[Pt(K¹-Ar)(µ-Cl)(PPh₃)]₂(trans-6d). Complex trans-6d

is a suitable precursor for the synthesis of a variety of monoaryl

complexes by bridge splitting. Thus, adding PPh₃and SMe₂

(Pt:L ) 1:2, CH₂Cl₂) or bubbling CO through a suspension of

trans-6d in CH₂Cl₂led to the corresponding complexes [Pt(κ¹-

Ar)Cl(PPh₃)(L)] (L ) PPh₃(trans-7), SMe₂(8a), CO (8b);

Scheme 4). Complexes trans-7 and 8a,b are air-stable in the

solid state and also in CDCl₃solutions, except for 8b, which

slowly decomposes in solution to give the starting complex

trans-6d. Probably, this decomposition can be ascribed to the

competition between CO and the phosphine ligand for the scarce

π donor electron density of platinum and to the low solubility

of trans-6d. The carbonyl complex 5c, in which no other good

π-acceptor is present, is stable in solution and in the solid state.

The room-temperature reaction of trans-6d with XyNC (Pt:L

) 1:1, 1:4) in CH₂Cl₂gave a mixture of three complexes that,

although they could not be separated, was probably composed

of the geometric isomers of composition [Pt(κ¹-Ar)Cl(PPh₃)-

(CNXy)] (8c1 + 8c2 + 8c3 ) 8c; Scheme 4). When the 1:1

reaction was followed by ¹H and ³¹P NMR in CD₂Cl₂, a product

containing κ¹-Ar, XyNC, and PPh₃ligands in a 1:1:1 molar ratio

and only one ³¹P singlet was observed. This compound slowly

decomposes to give the isolated mixture of complexes 8c. We

propose tentatively that this intermediate is the pentacoordinate

complex trans-[Pt(κ¹-Ar)(µ-Cl)(CNXy)(PPh₃)]₂(A, Scheme 4),

resulting from the coordination of one XyNC to each Pt atom

of trans-6d. When the mixture of isomers 8c was reﬂuxed in

acetone for 4.5 h, it transformed into the isomer 8c1, whose

greater thermodynamic stability is attributable to steric grounds.

Scheme 5

Complex trans-6d reacts with anionic ligands X (Pt:X ) 1)

to give the substitution or the addition product (Scheme 5). Thus,

with Tl(acac) it gave cis-[Pt(κ¹-Ar)(acac)(PPh₃)] (9) and with

(PPN)Cl it afforded cis-PPN[Pt(κ¹-Ar)Cl₂(PPh₃)] (PPN · 10). The

reaction with Tl(acac) had to be carried out in dry CH₂Cl₂and

under N₂because in the presence of moisture complex 9 was

obtained contaminated with trans-[{Pt(κ¹-Ar)(PPh₃)}₂(µ-OH)₂].⁸

Since CH₂Cl₂and acetone solutions of 9 are stable in the

presence of moisture, formation of trans-[{Pt(κ¹-Ar)(PPh₃)}₂(µ-

(22) Vicente, J.; Arcas, A.; Blasco, M. A.; Lozano, J.; Ram´ırez de

Arellano, M. C. Organometallics 1998, 17, 5374.

(23) Vicente, J.; Arcas, A.; Bautista, D.; Jones, P. G. Organometallics

1997, 16, 2127. Vicente, J.; Arcas, A.; Bautista, D.; Tiripicchio, A.;

Tiripicchio-Camellini, M. New J. Chem. 1996, 20, 345. Vicente, J.; Abad,

J. A.; Frankland, A. D.; Ram´ırez de Arellano, M. C. Chem. Eur. J. 1999,

5, 3066. Vicente, J.; Abad, J. A.; Frankland, A. D.; Lo´pez-Serrano, J.;

Ram´ırez de Arellano, M. C.; Jones, P. G. Organometallics 2002, 21, 272.

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.

2,6-Dinitroaryl Pt(II) and Pt(IV) Complexes

Organometallics, Vol. 28, No. 12, 2009 3509

Scheme 6

Scheme 7

OH)₂] probably arises from the hydrolysis of some intermediate

in the formation process of 9.

The reaction of trans-6d with bpy in the Pt:bpy molar ratio

1:1 afforded after 24 h cis-[Pt(κ¹-Ar)(PPh₃)(bpy)]Cl (11 · Cl)

(Scheme 5). At shorter reaction times, the reaction product was

a mixture or 11 · Cl and cis-[Pt(κ¹-Ar)(PPh₃)(bpy)](cis-[Pt(κ¹-

Ar)Cl₂(PPh₃)]) (11 · 10). The latter could be isolated by reacting

trans-6d with bpy in a Pt:bpy molar ratio of 2:1. trans-6d did

not react with ethylene, dimethyl maleate, dimethyl fumarate,

or dimethyl acetylenedicarboxylate.

of a mixture of two isomers (see Spectroscopic Properties).

Equimolecular amounts of 12 and PPh₃reacted to give a mixture

of products in which cis-[Pt(κ²-Ar)(κ¹-Ar)(PPh₃)]¹¹was identi-

ﬁed. The same product was obtained in moderate yield (65%)

using 2 equiv of PPh₃. Similarly, 12 reacted with 2 equiv of

AsPh₃, affording cis-[Pt(κ²-Ar)(κ¹-Ar)(AsPh₃)] (16); however,

its reaction with 1 equiv of AsPh₃gave (AsPh₃OH)[Pt(κ²-Ar)(κ¹-

Ar)Cl] (17). In both reactions, the ﬁrst step probably consists

of the oxidation of the ligand and the reduction of Pt to give

(EPh₃Cl)[Pt(κ²-Ar)(κ¹-Ar)Cl] (E ) P, As). Hydrolysis of this

intermediate affords 17 or the mixture of complexes observed

when the ligand is PPh₃. Replacement of the chloro ligand by

EPh₃leads to the isolated cis-[Pt(κ²-Ar)(κ¹-Ar)(EPh₃)]. We also

attempted the reaction between 12 and SbPh₃, but the starting

products were recovered unchanged.

Synthesis of Pt(IV) Complexes. The reaction of cis-[Pt(κ²-

Ar)(κ¹-Ar)(OH₂)]⁷with an excess of Cl₂in CCl₄(saturated

solution) or 1 equiv of PhICl₂gave only the stereoisomer (OC-

6-32)-[Pt(κ²-Ar)₂Cl₂] (12; Scheme 6), where both Ar groups

remain mutually cis, the κ¹-Ar ligand changes to κ²-Ar, and two

cis chloro ligands have been added. The reaction using Cl₂gave

initially a mixture of 12 and another isomer containing two

1

different κ²-Ar groups (1:0.3 molar ratio; H NMR in CDCl₃),

but after 19 h only 12 was observed.

trans-[Pt(κ²-Ar)(κ²-Ar)(CO)]¹¹reacts with an excess of Cl₂

(saturated solution in CCl₄), giving initially only the isomer (OC-

6-22)-[Pt(κ²-Ar)₂Cl₂] (13; Scheme 6), but its concentration

slowly decreased while that of its isomer 12 increased (after

18 h, the proportion 13:12 was 1.8:1). This slow isomerization

allowed the isolation of 13 after 20 min of reaction. The lower

stability of 13 must be caused by the transphobia (τ)^10,11,22,23

between the two trans carbon donor ligands, which is greater

than that between a carbon and other donor ligands: i.e., τ(aryl/

aryl) . τ(aryl/L) (L ) Cl- or O-donor ligand). In the solid state,

both isomers are stable at room temperature.

Crystal Structures. The crystal structures of HAr and the

complexes 2a · CH₂Cl₂, 2c, 3, 5a, trans-6b, trans-6c · CDCl₃,

trans-7 · Et₂O, 8a, 8c1, 9, 11 · 10 · 2CHCl₃, 12, 13, 16, and 17

have been determined (Figures 1-16 and Tables 1-4).

In HAr (Figure 1) the Me groups lie alternately above and

below the molecular plane. The angles between the ring and

the NO₂groups planes are 38.05 and 56.61°, showing the poor

π-acceptor character of these groups. However, the shortening

of C-OMe distances of the mutually meta groups (1.356(3)

and 1.354(3) Å) with respect to the other (1.375(3) Å) seems

to indicate that the -I effect of the nitro groups enhances the

π-donor ability of the nearest MeO groups.

fac-[Pt(κ²-Ar)Cl₃(PPh₃)] (14) was obtained by reacting [Pt(κ¹-

Ar)(µ-Cl)(PPh₃)]₂(6d) with an excess of PhICl₂(1:3). This

complex is stable in the solid state at room temperature, but it

loses Cl₂in CH₂Cl₂solution, giving the starting complex.

Reaction of 12 with 2 equiv of AgClO₄gave [Pt(κ²-

Ar)₂(H₂O)₂](ClO₄)₂(15; Scheme 7), which in solution consists

In all complexes, the platinum atom shows a slightly distorted

square planar (Pt(II)) or octahedral (Pt(IV)) coordination and

3510 Organometallics, Vol. 28, No. 12, 2009

Vicente et al.

Figure 3. Ellipsoid representation of 2c (50% probability). Selected

bond lengths (Å) and angles (deg): Pt-C(11) ) 2.034(3), Pt-C(3)#1

) 2.165(2), Pt-C(3) ) 2.165(2), Pt-C(2)#1 ) 2.252(2), Pt-C(2)

) 2.252(2), Pt-Br 2.4138(3), N(1)-O(2) ) 1.213(2), N(1)-O(1)

) 1.229(2), N(1)-C(12) ) 1.483(2), C(2)-C(2)#1 ) 1.367(4),

C(3)-C(3)#1)1.394(4);C(11)-Pt-C(3)#1)100.23(9),C(11)-Pt-C(3)

) 100.23(9), C(3)#1-Pt-C(3) ) 37.56(11), C(3)#1-Pt-C(2)#1

) 65.63(8), C(3)-Pt-C(2)#1 ) 77.45(8), C(3)#1-Pt-C(2) )

77.45(8), C(3)-Pt-C(2) ) 65.63(8), C(2)#1-Pt-C(2) ) 35.32(11),

C(11)-Pt-Br ) 90.66(8), C(2)#1-Pt-Br ) 98.54(6), C(2)-Pt-Br

) 98.54(6).

Figure 1. Ellipsoid representation of HAr (50% probability; solvent

omitted). Selected bond lengths (Å) and angles (deg): C(1)-C(2)

) 1.367(3), C(1)-C(6) ) 1.387(3), C(2)-C(3) ) 1.397(3),

C(2)-N(1) ) 1.474(3), C(3)-O(1) ) 1.354(3), C(3)-C(4) )

1.395(3), C(4)-O(2) ) 1.375(3), C(4)-C(5) ) 1.386(3), C(5)-O(3)

) 1.356(3), C(5)-C(6) ) 1.398(3), C(6)-N(2) ) 1.471(3),

O(4)-N(2) ) 1.226(3), O(5)-N(2) ) 1.232(3), O(6)-N(1) )

1.209(3), O(7)-N(1) ) 1.217(3); C(2)-C(1)-C(6) ) 117.3(2),

C(1)-C(2)-C(3) ) 123.5(2), C(1)-C(2)-N(1) ) 118.3(2),

C(3)-C(2)-N(1) ) 118.2(2), C(4)-C(3)-C(2) ) 117.4(2),

C(5)-C(4)-C(3) ) 121.2(2), C(4)-C(5)-C(6) ) 118.4(2),

C(1)-C(6)-C(5) ) 122.1(2), C(1)-C(6)-N(2) ) 117.0(2),

C(5)-C(6)-N(2) ) 120.8(2), O(6)-N(1)-O(7) ) 124.2(2),

O(6)-N(1)-C(2) ) 118.1(2), O(7)-N(1)-C(2) ) 117.6(2),

O(4)-N(2)-O(5) ) 124.4(2), O(4)-N(2)-C(6) ) 118.3(2),

O(5)-N(2)-C(6) ) 117.3(2).

Figure 4. Ellipsoid representation of 3 (50% probability). Selected

bond lengths (Å) and angles (deg): Pt-C(11) ) 1.957(4), Pt-O(1)

) 1.964(3), Pt-O(11) ) 1.999(3), Pt-O(2) ) 2.041(3), O(11)-

N(11) ) 1.303(4), O(12)-N(11) ) 1.208(4), O(16)-N(12) )

1.218(5), O(17)-N(12) ) 1.224(4), N(11)-C(12) ) 1.425(5),

N(12)-C(16))1.480(5);C(11)-Pt-O(1))95.78(13),C(11)-Pt-O(11)

) 81.42(13), O(1)-Pt-O(11) ) 176.19(12), C(11)-Pt-O(2) )

171.96(13), O(1)-Pt-O(2) ) 92.10(11), O(11)-Pt-O(2) )

90.63(11).

Figure 2. Ellipsoid representation of 2a (30% probability). Selected

bond lengths (Å) and angles (deg): Pt-N(21) ) 2.009(2), Pt-C(11)

) 2.013(3), Pt-N(31) ) 2.069(2), Pt-Cl(1) ) 2.2929(8),

N(11)-O(11) ) 1.222(3), N(11)-O(12) ) 1.227(3), N(11)-C(12)

) 1.466(4), N(12)-O(16) ) 1.222(3), N(12)-O(17) ) 1.223(3),

N(12)-C(16) ) 1.475(4); N(21)-Pt-C(11) ) 96.72(10), N(21)-

Pt-N(31) ) 80.33(10), C(11)-Pt-Cl(1) ) 88.83(8), N(31)-

Pt-Cl(1) ) 94.14(7).

complexes of the type [PtR(O,O-ꢀ-diketonate)L] (R ) any

C-donor ligand; L ) any P-donor ligand) reveals only two

crystal structures of complexes in which there is no signiﬁcant

difference between the Pt-O distances: [PtEt(O,O-acac)(PPh₃)]

(transtoC,2.064(5)Å;transtoP,2.087(6)Å),²⁴[{Pt(CH₂C₆H₄P(o-

tolyl)₂-κC,P}(acac-O,O)HgBr(µ-Br)}₂(µ-HgBr₂)] (trans to C,

2.090(9) Å; trans to P, 2.066(9) Å).²⁵

Complexes in which the aryl ligand is trans to the ligand Cl

show decreasing values of Pt-C bond distances from Pt(IV)

(12, Pt-C(κ²-Ar) ) 2.039(5) Å) to Pt(II) complexes (7,

(Pt-C(κ¹-Ar) ) 2.005(4) Å ≈ 11 · 10, Pt-C(κ¹-Ar) ) 2.000 Å

≈ 17, Pt-C(κ²-Ar) ) 1.994(4) Å), which might be attributable

their geometries are in agreement with those proposed in

Schemes 1-7. The following scales of trans inﬂuence can be

deduced by comparing the bond distances (Å) Pt-X trans to

different ligands L (Pt-X_L) in the same complex as follows:

Ar > Cl (2a, Pt-N_Ar) 2.069(2) > Pt-N_Cl) 2.009(2); 12:

Pt-O_Ar) 2.099(3)) > Pt-O_Cl) 2.035(3)), Ar > Br (2c, Pt-C_Ar

) 2.252(2) > Pt-C_Br) 2.165(2)), Ar > ON(Ar)O (3, Pt-O_Ar

) 2.041(3) > Pt-O_ON(O)Ar) 1.964(4); 12, Pt-Cl_Ar) 2.3599(12)

> Pt-Cl_ON(O)Ar) 2.2842(13)), Ar > π-(H₂CdCHR) (R ) H,

Ph) (trans-6b, Pt-Br_Ar) 2.5387(6), 2.5446(6) > Pt-Br_{H CdCH}

) 2.4740(6), 2.4457(6); trans-6c, Pt-Br_Ar, 2.5486(6), 2.5401(6)

> Pt-Br_{H CdCHPh}) 2.4659(6), 2.4695(6)), Ar > PPh₃(11 · 10,

Pt-N_Ar)²2.093(5) > Pt-N_P) 2.061(5); Pt-Cl_Ar) 2.3858(16)

> Pt-Cl_P) 2.3449(17); however, in 9 the trans inﬂuence of

Ar ≈ PPh₃(Pt-O_Ar) 2.0533(17) ≈ Pt-O_P) 2.0549(16)). A

search in the Cambridge Crystallographic Database for Pt(II)

2

(24) Cavell, K. J.; Jin, H.; Skelton, B. W.; White, A. H. J. Chem. Soc.,

Dalton Trans. 1993, 1973.

(25) Ara, I.; Falvello, L. R.; Fornies, J.; Sicilia, V.; Villarroya, P.

Organometallics 2000, 19, 3091.

2,6-Dinitroaryl Pt(II) and Pt(IV) Complexes

Organometallics, Vol. 28, No. 12, 2009 3511

Figure 5. Ellipsoid representation of 5a (50% probability). Selected

bond lengths (Å) and angles (deg): Pt-N(20) ) 1.950(5), Pt-C(11)

) 1.983(7), Pt-O(11) ) 1.990(4), Pt-Br ) 2.4629(8), O(11)-N(11)

) 1.307(7), O(12)-N(11) ) 1.210(7), N(11)-C(12) ) 1.402(8),

O(16)-N(12) ) 1.218(7), O(17)-N(12) ) 1.213(7), N(12)-

C(16) ) 1.491(7); N(20)-Pt-C(11) ) 100.1(3), C(11)-Pt-O(11)

) 80.7(2), N(20)-Pt-Br ) 89.69(19), O(11)-Pt-Br ) 89.49(15).

Figure 7. Ellipsoid representation of trans-6c (30% probability).

Selected bond lengths (Å) and angles (deg): Pt(1)-C(31) )

2.007(5), Pt(1)-C(28) ) 2.138(5), Pt(1)-C(27) ) 2.213(5),

Pt(1)-Br(1) ) 2.4659(6), Pt(1)-Br(2) ) 2.5486(6), Br(1)-Pt(2)

) 2.5401(6), Pt(2)-C(41) ) 2.005(5), Pt(2)-C(18) ) 2.128(5),

Pt(2)-C(17) ) 2.189(5), Pt(2)-Br(2) ) 2.4695(6), C(32)-N(31)

) 1.469(6), C(36)-N(32) ) 1.468(6), C(42)-N(41) ) 1.473(6),

C(46)-N(42) ) 1.474(6), N(31)-O(32) ) 1.209(6), N(31)-O(31)

) 1.206(6), N(32)-O(37) ) 1.217(5), N(32)-O(36) ) 1.225(5),

N(41)-O(42) ) 1.221(5), N(41)-O(41) ) 1.234(5), N(42)-O(47)

) 1.208(5), N(42)-O(46) ) 1.227(6), C(17)-C(18) ) 1.386(7),

C(27)-C(28) ) 1.392(7); C(31)-Pt(1)-C(28) ) 91.52(19),

C(31)-Pt(1)-C(27) ) 92.37(19), C(28)-Pt(1)-C(27) ) 37.27(18),

C(31)-Pt(1)-Br(1) ) 88.71(13), C(28)-Pt(1)-Br(2) ) 94.67(15),

C(27)-Pt(1)-Br(2) ) 95.52(14), Br(1)-Pt(1)-Br(2) ) 83.85(2),

Pt(1)-Br(1)-Pt(2) ) 82.34(2), C(41)-Pt(2)-C(18) ) 92.6(2),

C(41)-Pt(2)-C(17) ) 88.34(19), C(18)-Pt(2)-C(17) ) 37.42(19),

C(41)-Pt(2)-Br(2) ) 90.12(13), C(18)-Pt(2)-Br(1) ) 91.81(16),

C(17)-Pt(2)-Br(1) ) 98.24(14), Br(2)-Pt(2)-Br(1) ) 83.96(2),

Pt(2)-Br(2)-Pt(1) ) 82.09(2). The fold angle between the two

PtBr₂planes is 55.5°.

Figure 6. Ellipsoid representation of trans-6b (30% probability).

Selected bond lengths (Å) and angles (°): Pt(1)-C(11) ) 2.010(5),

Pt(1)-C(2) ) 2.147(6), Pt(1)-C(1) ) 2.154(6), Pt(1)-Br(1) )

2.4740(6), Pt(1)-Br(2) ) 2.5387(6), Pt(2)-C(21) ) 2.008(5),

Pt(2)-C(4) ) 2.147(6), Pt(2)-C(3) ) 2.150(6), Pt(2)-Br(2) )

2.4457(6), Pt(2)-Br(1) ) 2.5446(6), N(11)-O(12) ) 1.153(7),

N(11)-O(11) ) 1.214(7), N(11)-C(12) ) 1.458(7), N(12)-O(16)

) 1.208(6), N(12)-O(17) ) 1.238(7), N(12)-C(16) ) 1.473(7),

N(21)-O(21) ) 1.180(6), N(21)-O(22) ) 1.213(6), N(21)-C(22)

) 1.468(7), N(22)-O(26) ) 1.210(6), N(22)-O(27) ) 1.218(6),

N(22)-C(26) ) 1.463(7), C(1)-C(2) ) 1.368(9), C(3)-C(4) )

1.356(10); C(11)-Pt(1)-C(2) ) 92.5(2), C(11)-Pt(1)-C(1) )

90.7(2), C(2)-Pt(1)-C(1) ) 37.1(2), C(11)-Pt(1)-Br(1) )

90.88(17), C(2)-Pt(1)-Br(2) ) 90.73(17), C(1)-Pt(1)-Br(2) )

92.97(18), Br(1)-Pt(1)-Br(2) ) 85.57(2), C(21)-Pt(2)-C(4) )

92.2(2), C(21)-Pt(2)-C(3) ) 90.8(2), C(4)-Pt(2)-C(3) ) 36.8(3),

C(21)-Pt(2)-Br(2) ) 90.11(15), C(4)-Pt(2)-Br(1) ) 91.79(18),

C(3)-Pt(2)-Br(1) ) 92.33(17), Br(2)-Pt(2)-Br(1) ) 86.03(2).

The fold angle between the two PtBr₂planes is 54.9°.

Figure 8. Ellipsoid representation of trans-7 (30% probability).

Selected bond lengths (Å) and angles (deg): Pt-C(1) ) 2.005(4),

Pt-P(1) ) 2.3127(10), Pt-P(2) ) 2.3294(11), Pt-Cl ) 2.3781(10),

N(1)-O(2) ) 1.198(5), N(1)-O(1) ) 1.207(5), N(1)-C(2) )

1.488(5), N(2)-O(7) ) 1.204(5), N(2)-O(6) ) 1.226(5), N(2)-C(6)

) 1.484(5); C(1)-Pt-P(1) ) 91.07(11), C(1)-Pt-P(2) )

89.91(11), P(1)-Pt-Cl ) 88.10(4), P(2)-Pt-Cl ) 90.92(4).

to the weaker π(PtfC(Ar)) bond component for Pt(IV).

Consequently, Pt(IV) complex 13 has the longest Pt-C bond

distances (2.076(6), 2.073(6) Å) of the series because, in addition

to the high oxidation state of the metal center, the mutually

trans aryl ligands have a very high trans inﬂuence. However,

these values are shorter than those found in cis-bis(tetrahy-

drothiophene)bis(4,4′-bis(triﬂuoromethyl)biphenyl-2,2′-diyl-

)platinum(IV) (2.108 Å),²⁶(OC-6-32)-[Pt(C₆Cl₅)₂(κ²C,Cl-

C₆Cl₅)₂] (2.119(7), 2.139(7) Å),²⁷or (n-Bu₄N)[(OC-6-23)-

Pt(C₆F₅)₄Br(CO)] (2.09(2)-2.13(2) Å).²⁸

The other Pt(II)-C(Ar) bond distances decrease smoothly

from those having with higher trans inﬂuence trans to Ar,

namely PPh₃(8c1), π-(oleﬁn) (2c), and AsPh₃(16) (2.070(11)-

2.029(2) Å), to those with lower trans inﬂuence, Cl (7, 8a,

(27) Fornie´s, J.; Menjon, B.; Sanzcarrillo, R. M.; Tomas, M.; Connelly,

N. G.; Crossley, J. G.; Orpen, A. G. J. Am. Chem. Soc. 1995, 117, 4295.

(28) Fornie´s, J.; Gomez Saso, M. A.; Martin, A.; Mart´ınez, F.; Menjon,

B.; Navarrete, J. Organometallics 1997, 16, 6024.

(26) Marsh, R. E. Acta Crystallogr., Sect. B 1997, 53, 317.

3512 Organometallics, Vol. 28, No. 12, 2009

Vicente et al.

Figure 9. Ellipsoid representation of 8a (50% probability). Selected

bond lengths (Å) and angles (deg): Pt-C(11) ) 2.0131(16), Pt-P

) 2.2591(4), Pt-S ) 2.3571(4), Pt-Cl ) 2.3584(4), N(11)-O(11)

) 1.215(2), N(11)-O(12) ) 1.218(2), N(11)-C(12) ) 1.474(2),

N(12)-O(17) ) 1.224(2), N(12)-O(16) ) 1.225(2), N(12)-C(16)

) 1.472(2); C(11)-Pt-P ) 93.12(4), C(11)-Pt-S ) 87.39(4),

P-Pt-S ) 174.437(15), C(11)-Pt-Cl ) 173.80(5), P-Pt-Cl )

88.102(16), S-Pt-Cl ) 91.980(17).

Figure 11. Ellipsoid representation of 9 (30% probability). Selected

bond lengths (Å) and angles (deg): Pt-C(11) ) 1.996(2), Pt-O(8)

) 2.0533(17), Pt-O(9) ) 2.0549(16), Pt-P ) 2.2232(6), N(1)-

O(1) ) 1.207(3), N(1)-O(2) ) 1.212(3), N(1)-C(12) ) 1.468(3),

N(2)-O(6) ) 1.221(3), N(2)-O(7) ) 1.225(3), N(2)-C(16) )

1.470(3); C(11)-Pt-O(9) ) 88.53(8), O(8)-Pt-O(9) ) 91.90(7),

C(11)-Pt-P ) 92.46(6), O(8)-Pt-P ) 87.14(5).

Figure 12. Ellipsoid representation of 11 · 10 (50% probability).

Selected bond lengths (Å) and angles (deg): Pt(1)-C(11) )

2.003(7), Pt(1)-N(51) ) 2.061(5), Pt(1)-N(61) ) 2.093(5),

Pt(1)-P(1) ) 2.2589(18), P(1)-C(21) ) 1.817(6), Pt(2)-C(71)

) 2.000(7), Pt(2)-P(2) ) 2.2246(18), Pt(2)-Cl(1) ) 2.3449(17),

Pt(2)-Cl(2) ) 2.3858(16); C(11)-Pt(1)-N(51) ) 93.9(2),

C(11)-Pt(1)-N(61) ) 172.9(2), N(51)-Pt(1)-N(61) ) 79.0(2),

C(11)-Pt(1)-P(1) ) 89.41(18), N(51)-Pt(1)-P(1) ) 174.88(15),

N(61)-Pt(1)-P(1) ) 97.61(17), C(71)-Pt(2)-P(2) ) 92.32(18),

C(71)-Pt(2)-Cl(1) ) 87.31(18), P(2)-Pt(2)-Cl(1) ) 179.62(7),

C(71)-Pt(2)-Cl(2) ) 176.16(18), P(2)-Pt(2)-Cl(2) ) 90.97(6),

Cl(1)-Pt(2)-Cl(2) ) 89.39(6).

The aryl and the chelate rings of the κ²-Ar ligands are

almost coplanar (maximum interplanar angles ca. 8°), while

in κ¹-Ar ligands the phenyl ring is almost perpendicular to

the coordination plane (interplanar angles range from 71°

for17to90°for2c).Ashasbeenshownpreviously^{4,7,9,11,13,22,29-31}

for the κ²-Ar ligands, the N-O(M) bond (mean value 1.307

Å) is longer than the other N-O bond (mean value 1.208

Å), which in turn is similar to the N-O distances found in

κ¹-Ar ligands (mean value 1.219 Å); furthermore, the C-N

bond length is shorter (mean value 1.418 Å) than in κ¹-Ar

ligands (mean value 1.475 Å). These values, which curiously

do not depend on the oxidation state of the metal, can be

interpreted by assuming that (1) the electron density trans-

ferred from the oxygen atom to Pt in κ²-Ar ligands is

compensated by an electronic donation from the aryl group

to the N atom (-M effect) and (2) this donation does not

occur in κ¹-Ar ligands, which is also clear on taking into

account that the nitro group in these ligands is not coplanar

Figure 10. Ellipsoid representation of one of the two independent

molecules of (SP-4-3)-[Pt(κ¹-Ar)Cl(CNXy)(PPh₃)] (8c1) (30%

probability). Selected bond lengths (Å) and angles (deg) for the

two independent molecules are as follows. 8c1: Pt(1)-C(20) )

1.911(11), Pt(1)-C(11) ) 2.060(10), Pt(1)-P(1) ) 2.316(4),

Pt(1)-Cl(1) ) 2.328(3), N(11)-O(12) ) 1.206(12), N(11)-O(11)

) 1.221(12), N(11)-C(12) ) 1.487(12), N(12)-O(16) ) 1.197(12),

N(12)-O(17) ) 1.207(12), N(12)-C(16) ) 1.491(11), N(20)-C(20)

) 1.134(12); C(20)-Pt(1)-C(11) ) 86.9(5), C(20)-Pt(1)-P(1)

) 94.8(4), C(11)-Pt(1)-Cl(1) ) 87.8(3), P(1)-Pt(1)-Cl(1) )

90.40(12). 8c1′: Pt(2)-C(20′) ) 1.909(12), Pt(2)-C(11′) )

2.070(11), Pt(2)-P(2) ) 2.323(4), Pt(2)-Cl(2) ) 2.319(3),

N(11′)-O(12′) ) 1.187(13), N(11′)-O(11′) ) 1.185(12), N(11′)-

C(12′) ) 1.488(12), N(12′)-O(16′) ) 1.216(12), N(12′)-O(17′)

) 1.231(12), N(12′)-C(16′) ) 1.459(12), N(20′)-C(20′) )

1.133(12); C(20′)-Pt(2)-C(11′) ) 87.1(5), C(20′)-Pt(2)-P(2) )

94.7(4), C(11′)-Pt(2)-Cl(2) ) 86.7(3), Cl(2)-Pt(2)-P(2) )

91.55(13).

11 · 10, 17), bpy (2a), Br (5a, 6b,c), O-acac (3, 9), and ON(O)Ar

(12, 16, 17) (2.0131(16)-1.957(4) Å). However, the differences

in Pt(II)-C(Ar) bond distances are not sufﬁcient to allow us to

propose a scale of trans inﬂuence for these ligands. The

Pt(II)-C(κ²-Ar) distances are slightly shorter than Pt(II)-C(κ¹-

Ar) bond distances when the trans ligand is Br (1.983(7) Å in

5a vs 2.005(5), 2.007(5) Å in 6c or 2.008(5), 2.010(5) Å in 6b)

or O,O-acac (1.957(4) Å in 3 vs 1.996(2) Å) but not signiﬁcantly

different when the trans ligand is Cl (1.994(4) Å in 17 vs

2.000(7) Å in 11 · 10 or 2.005(4) Å in 7).

2,6-Dinitroaryl Pt(II) and Pt(IV) Complexes

Organometallics, Vol. 28, No. 12, 2009 3513

Figure 13. Ellipsoid representation of complex 12 (30% prob-

ability). Selected bond lengths (Å) and angles (deg): Pt-C(11) )

1.994(5), Pt-O(11) ) 2.035(3), Pt-C(21) ) 2.039(5), Pt-O(21)

) 2.099(3), Pt-Cl(1) ) 2.2842(13), Pt-Cl(2) ) 2.3599(12),

C(12)-N(11) ) 1.407(6), C(16)-N(12) ) 1.474(6), C(22)-N(21)

) 1.429(6), C(26)-N(22) ) 1.488(6), N(11)-O(12) ) 1.216(5),

N(11)-O(11) ) 1.306(5), N(12)-O(17) ) 1.217(6), N(12)-O(16)

) 1.226(5), N(21)-O(22) ) 1.202(5), N(21)-O(21) ) 1.305(5),

N(22)-O(27))1.219(5),N(22)-O(26))1.222(5);C(11)-Pt-O(11)

) 81.18(16), C(11)-Pt-C(21) ) 103.41(19), O(11)-Pt-C(21) )

89.66(17), C(11)-Pt-O(21) ) 172.85(17), O(11)-Pt-O(21) )

92.31(13), C(21)-Pt-O(21) ) 79.37(16), C(11)-Pt-Cl(1) )

101.52(14), O(11)-Pt-Cl(1) ) 176.31(10), C(21)-Pt-Cl(1) )

87.27(15), O(21)-Pt-Cl(1) ) 85.12(10), C(11)-Pt-Cl(2) )

84.74(13), O(11)-Pt-Cl(2) ) 90.01(10), C(21)-Pt-Cl(2) )

171.69(14), O(21)-Pt-Cl(2) ) 92.35(9), Cl(1)-Pt-Cl(2) )

92.74(5).

Figure 15. Ellipsoid representation of complex 16 · CHCl₃(50%

probability). Selected bond lengths (Å) and angles (deg): Pt-C(21)

) 1.990(2), Pt-C(11) ) 2.029(2), Pt-O(11) ) 2.0780(15), Pt-As

) 2.4154(3), O(11)-N(11) ) 1.293(2), O(12)-N(11) ) 1.214(2),

O(16)-N(12) ) 1.213(3), O(17)-N(12) ) 1.225(3), O(21)-N(21)

) 1.224(2), O(22)-N(21) ) 1.224(2), O(26)-N(22) ) 1.213(3),

O(27)-N(22) ) 1.207(3), C(12)-N(11) ) 1.432(3), C(16)-N(12)

) 1.477(3), C(22)-N(21) ) 1.468(3), C(26)-N(22) ) 1.480(3);

C(21)-Pt-C(11) ) 99.58(8), C(11)-Pt-O(11) ) 79.31(7),

C(21)-Pt-As ) 90.00(6), C(11)-Pt-As ) 170.18(6), O(11)-

Pt-As ) 91.36(4).

Figure 16. Ellipsoid representation of complex 17 (30% prob-

ability). Selected bond lengths (Å) and angles (deg): Pt-C(21) )

1.991(3), Pt-C(11) ) 1.994(4), Pt-O(11) ) 2.080(3), Pt-Cl )

2.3513(10), C(12)-N(11) ) 1.438(5), N(11)-O(12) ) 1.201(4),

N(11)-O(11) ) 1.284(4), C(16)-N(12) ) 1.476(5), N(12)-O(17)

) 1.215(5), N(12)-O(16) ) 1.224(5), C(22)-N(21) ) 1.472(5),

N(21)-O(22) ) 1.223(5), N(21)-O(21) ) 1.239(5), C(26)-N(22)

) 1.481(4), N(22)-O(26) ) 1.213(4), N(22)-O(27) ) 1.221(4);

C(21)-Pt-C(11) ) 101.53(17), C(21)-Pt-O(11) ) 174.62(13),

C(11)-Pt-O(11) ) 80.56(13), C(21)-Pt-Cl ) 90.63(13),

C(11)-Pt-Cl ) 167.65(11), O(11)-Pt-Cl ) 87.52(8).

Figure 14. Ellipsoid representation of complex 13 (50% prob-

ability). Selected bond lengths (Å) and angles (deg): Pt(1)-O(7)

) 2.020(4), Pt(1)-O(17) ) 2.035(4), Pt(1)-C(11) ) 2.073(6),

Pt(1)-C(1) ) 2.076(6), Pt(1)-Cl(1) ) 2.2785(16), Pt(1)-Cl(2)

) 2.2900(16), N(1)-O(6) ) 1.210(7), N(1)-O(7) ) 1.322(7),

N(1)-C(6) ) 1.407(8), N(2)-O(2) ) 1.216(7), N(2)-O(1) )

1.232(7), N(2)-C(2) ) 1.485(8), N(3)-O(16) ) 1.202(7),

N(3)-O(17) ) 1.332(7), N(3)-C(16) ) 1.404(8), N(4)-O(11) )

1.218(7), N(4)-O(12) ) 1.225(7), N(4)-C(12) ) 1.471(8);

O(7)-Pt(1)-O(17) ) 89.26(18), O(7)-Pt(1)-C(11) ) 91.4(2),

O(17)-Pt(1)-C(11) ) 80.1(2), O(7)-Pt(1)-C(1) ) 80.3(2),

O(17)-Pt(1)-C(1) ) 91.5(2), C(11)-Pt(1)-C(1) ) 168.3(2),

O(7)-Pt(1)-Cl(1) ) 89.35(14), O(17)-Pt(1)-Cl(1) ) 178.59(13),

C(11)-Pt(1)-Cl(1) ) 100.20(18), C(1)-Pt(1)-Cl(1) ) 88.02(17),

O(7)-Pt(1)-Cl(2) ) 178.36(13), O(17)-Pt(1)-Cl(2) ) 89.52(14),

C(11)-Pt(1)-Cl(2) ) 87.34(17), C(1)-Pt(1)-Cl(2) ) 100.81(18),

Cl(1)-Pt(1)-Cl(2) ) 91.88(6).

(1.219 Å) calculated using the rest of such distances in κ¹-

Ar ligands. These oxygen atoms display unusually high U

values (and/or are slightly disordered), and the apparently

short bonds are probably an artifact attributable to libration

effects.

The molecule of 2c displays crystallographic mirror

symmetry, with the atoms Pt, Br, C11, C14, O4, C16, and

C4 lying in the mirror plane. The molecules of 3 are stacked,

forming inversion-symmetric dimers in which the vector

formed by the center of the κ²-Ar ligand of one molecule

and the metal atom of other molecule has a length of 3.61 Å

and forms an angle of 87° with the plane of the κ²-Ar ring

(Figure 17). This is similar to that found in its homologous

and isostructural Pd complex.²²

with the aryl group (interplanar angles range from 50 to 85°).

There is only one pair of N-O bond distances, in the complex

trans-6b (N(11)-O(12) ) 1.153(7) Å and N(21)-O(21) )

1.180(6) Å), that are signiﬁcantly below the mean value

3514 Organometallics, Vol. 28, No. 12, 2009

Vicente et al.

Table 1. Crystal Data and Structure Reﬁnement Details of Compounds HAr, 2a · CH₂Cl₂, 2c, and 3

HAr

2a · CH₂Cl₂

2c

3

formula

fw

C₉H₁₀N₂O₇

258.19

C₂₀H₁₉Cl₃N₄O₇Pt

728.83

C₁₆H₁₇BrN₂O₇Pt

624.32

C₁₄H₁₆N₂O₉Pt

551.38

temp (K)

cryst syst

cryst habit

cryst size (mm)

space group

a (Å)

b (Å)

c (Å)

R (deg)

ꢀ (deg)

γ (deg)

V (Å³)

173(2)

133(2)

triclinic

monoclinic

orange block

0.42 × 0.23 × 0.21

P2₁/n

10.441(2)

7.133(2)

15.440(2)

90

100.59(2)

90

1130.3(4)

4

monoclinic

yellow prism

0.16 × 0.07 × 0.07

P2₁/n

9.8232(8)

18.8199(14)

13.6122(11)

90

106.692(4)

90

2410.5(3)

4

monoclinic

pale yellow lath

0.18 × 0.10 × 0.10

P2₁/m

6.6672(4)

10.1737(8)

14.2564(11)

90

101.119(4)

90

948.86(12)

2

red needle

0.23 × 0.10 × 0.06

j

P1

7.8635(12)

10.194(2)

11.036(2)

72.721(6)

79.293(6)

78.820(6)

820.9(3)

2

Z

F_calcd(Mg m^-3

)

1.517

0.133

536

2.008

6.20

1408

2.185

9.54

592

2.231

8.60

528

µ(Mo KR) (mm^-1

F(000)

)

θ range (deg)

no. of rﬂns coll

3.16-25.00

3227

1.9-30.0

40 029

2.0-30.0

19 121

2.0-30.2

5375

no. of indep rﬂns/R_int

transmssn

1987/0.046

7065/0.060

0.728-0.514

47/319

0.93

0.0251

0.0480

1.13/-0.86

2924/0.044

0.701-0.053

1/142

1.03

0.0161

0.0377

1.02/-1.01

5375/-

0.626-0.367

56/241

1.07

0.0284

0.0585

1.72/-1.33

no. of restraints/params

goodness of ﬁt on F²

R1 (I > 2σ(I))

0/166

0.862

0.0431

0.1060

wR2 (all rﬂns)

largest diff peak/hole (e Å^-3

)

0.191/ -0.255

Table 2. Crystal Data and Structure Reﬁnement Details of Compounds 5a, trans-6b, trans-6c · CDCl₃, and trans-7 · Et₂O

5a

trans-6b

trans-6c · CDCl₃

trans-7 · Et₂O

formula

fw

C₁₁H₁₂BrN₃O₇Pt

573.24

133(2)

C₂₂H₂₆Br₂N₄O₁₄Pt₂

1120.47

133(2)

C₃₄H₃₅DBr₂Cl₃N₄O₁₄Pt₂

1393.02

133(2)

C₄₉H₄₉ClN₂O₈P₂Pt

1086.38

133(2)

monoclinic

yellow tablet

0.3 × 0.3 × 0.12

P2₁/n

12.0365(11)

18.4161(16)

20.8327(16)

90

91.435(4)

90

temp (K)

cryst syst

cryst habit

cryst size (mm)

space group

a (Å)

b (Å)

c (Å)

R (deg)

ꢀ (deg)

γ (deg)

V (Å³)

monoclinic

red needle

0.3 × 0.04 × 0.02

P2₁/c

7.8089(11)

12.0507(14)

16.434(2)

90

97.118(10)

90

1534.6(3)

4

monoclinic

pale brown prism

0.33 × 0.13 × 0.07

C2/c

21.9820(14)

11.8465(8)

24.291(2)

90

101.631(4)

90

6195.8(8)

8

monoclinic

pale brown plate

0.35 × 0.17 × 0.04

P2₁/n

14.485(2)

20.009(3)

14.693(2)

90

94.47(2)

90

4245.5(12)

4

4616.4(7)

4

1.563

3.22

2184

Z

F_calcd(Mg m^-3

)

2.481

11.79

1072

2.402

11.67

4192

2.180

8.72

2648

µ(Mo KR) (mm^-1

F(000)

)

θ range (deg)

no. of rﬂns coll

2.1-30.6

5781

1.9-30.0

69 726

1.7-30.0

87 786

1.5-30.0

95 127

no. of indep rﬂns/R_int

transmssn

5781/-

0.798-0.424

207/210

1.18

0.0361

0.0811

9084/0.068

0.695-0.402

96/427

0.96

0.0336

0.0789

1.78/-0.94

12 414/0.063

0.677-0.141

118/571

0.99

0.0317

0.0822

2.05/-1.84

13 475/0.066

0.746-0.536

182/571

1.02

0.0354

0.1009

no. of restraints/params

goodness of ﬁt on F²

R1 (I > 2σ(I))

wR2 (all rﬂns)

largest diff peak/hole (e Å^-3

)

1.49/-1.10

2.42/-1.39

The dinuclear complexes 6b,c are not far from approximate

inversion symmetry with two bridging bromo ligands and

two mutually trans κ¹-Ar groups. The two coordination planes

subtend an angle of 125° (6b) and 129° (6c). In the crystals

of 8c1, two crystallographically independent, but very similar,

units are present. One of these is represented in Figure 4.

In complex 17 a short Cl · · · HO hydrogen bond is formed

between the anion [Pt(κ²-Ar)(κ¹-Ar)Cl] and the HOAsPh₃

cation (H · · · Cl ) 2.17 Å, O · · · Cl ) 2.998(4) Å, O · · · H · · · Cl

) 167°). Consequently, the Pt-Cl bond distance is signiﬁ-

cantlylonger(2.3513(10)Å)thanintheanalogous[Ph₃PCH₂Ph]-

[Pt(κ²-Ar)(κ¹-Ar)Cl]⁷(2.3367(16) Å).

(4.35-3.52) from κ¹-Ar and/or κ²-Ar, respectively, expected for

the proposed structures in Schemes 1-7, except when some

accidental overlap occurs (e.g., in 17) or some transformation or

1

equilibrium occurs in solution. Thus, the room-temperature H

NMR spectrum of CDCl₃solutions of the 1:1 mixture of cis- and

trans-1a shows ﬁve MeO singlets (2:1:1:1:1), due to an accidental

coincidence of two singlets, while in acetone-d₆solutions a fast

equilibrium occurs between them because three (1:1:1) singlets are

observed. When the temperature is lowered, six singlets (1:1:1:2:

2:2) are observed at -30 °C (1:2 mixture of cis- and trans-1a)

and six (1:1:1:1:1:1) singlets at -75 °C (1:1 mixture). A possible

intermediate for the conversion of both isomers could be the

monomer [Pt(κ²-Ar)Cl{OC(CD₃)₂}], which might be responsible

for broad and narrow small resonances observed at -75 °C.

Spectroscopic Properties. The ¹H NMR and ¹³C{¹H} NMR

spectra of the complexes show the 2:1 and/or 1:1:1 MeO resonances

2,6-Dinitroaryl Pt(II) and Pt(IV) Complexes

Organometallics, Vol. 28, No. 12, 2009 3515

Table 3. Crystal Data and Structure Reﬁnement Details of Compounds, 8a,c, 9, and 11 · 10 · 2CHCl₃

8a

8c

9

11 · 10 · 2CHCl₃

formula

fw

C₂₉H₃₀ClN₂O₇PPtS

812.12

C₃₆H₃₃ClN₃O₇PPt

881.16

C₃₂H₃₁N₂O₉PPt

813.65

C₆₆H₅₈Cl₈N₆O₁₄P₂Pt₂

1894.90

temp (K)

cryst syst

cryst habit

cryst size (mm)

space group

a (Å)

b (Å)

c (Å)

R (deg)

ꢀ (deg)

γ (deg)

V (Å³)

133(2)

triclinic

133(2)

triclinic

133(2)

monoclinic

colorless tablet

0.25 × 0.11 × 0.03

P2₁

10.2286(12)

18.145(2)

19.724(2)

90

104.636(2)

90

3541.9(7)

4

monoclinic

pale brown tablet

0.19 × 0.15 × 0.05

Pn

10.3837(6)

14.7111(8)

23.2619(12)

90

94.900(4)

90

3540.4(3)

2

pale yellow tablet

0.33 × 0.26 × 0.16

pale yellow fragment

0.24 × 0.18 × 0.16

j

P1

9.6776(4)

10.6644(4)

16.2538(6)

72.051(4)

86.321(4)

72.729(4)

1523.20(10)

2

9.4446(6)

10.1492(6)

16.6855(11)

87.571(4)

86.830(4)

77.603(4)

1558.94(17)

2

Z

F_calcd(Mg m^-3

)

1.771

4.86

800

1.652

4.13

1744

1.733

4.61

804

1.778

4.36

1860

µ(Mo KR) (mm^-1

F(000)

)

θ range (deg)

no. of rﬂns coll

1.3-30.0

35 012

1.1-28.3

56 496

1.2-30.0

32 857

1.4-30.0

80 738

no. of indep rﬂns/R_int

transmssn

8853/0.022

0.564-0.381

78/384

1.05

0.0160

0.0407

1.47/-0.49

17 120/0.097

0.886-0.425

1495/884

0.96

0.0576

0.1072

9071/0.036

0.695-0.574

79/411

0.96

0.0243

0.0477

1.33/-0.50

20 408/0.078

0.773-0.634

517/889

0.88

0.0453

0.0720

3.02/-1.22

no. of restraints/params

goodness of ﬁt on F²

R1 (I > 2σ(I))

wR2 (all rﬂns)

largest diff peak/hole (e Å^-3

)

4.23/-4.30

Table 4. Crystal Data and Structure Reﬁnement Details of Compounds 12, 13, 16 · CDCl₃, and 17

12

13

16 · CDCl₃

17

formula

fw

C₁₈H₁₈Cl₂N₄O₁₄Pt

780.35

173(2)

C₁₈H₁₈Cl₂N₄O₁₄Pt

780.35

100(2)

C₃₇H₃₃DAsCl₃N₄O₁₄Pt

1136.05

143(2)

monoclinic

red block

0.27 × 0.19 × 0.08

P2₁/c

19.2324(14)

9.5645(8)

22.5031(18)

90

96.664(3)

90

C₃₆H₃₄AsClN₄O₁₅Pt

1068.13

143(2)

orthorhombic

red plate

0.27 × 0.10 × 0.02

Pca2₁

14.3292(12)

15.3241(12)

17.9615(14)

90

3944.0(5)

4

1.799

temp (K)

cryst syst

cryst habit

cryst size (mm)

space group

a (Å)

b (Å)

c (Å)

R (deg)

ꢀ (deg)

γ (deg)

V (Å³)

triclinic

monoclinic

yellow needle

0.08x 0.07 × 0.02

P2₁/n

13.2940(7)

10.7745(6)

16.8442(9)

90

93.058(2)

90

2409.3(2)

4

orange-yellow tablet

0.4 × 0.2 × 0.06

j

P1

8.4200(10)

9.6781(12)

16.8519(18)

96.815(8)

97.220(8)

110.295(8)

1258.2(3)

2

4111.43(6)

4

1.836

4.48

2232

Z

F_calcd(Mg m^-3

)

2.060

5.87

756

2.151

6.128

1512

µ(Mo KR) (mm^-1

F(000)

)

4.53

2104

θ range (deg)

no. of rﬂns coll

3.0-25.0

4458

1.90-27.10

26 504

1.8-30.0

42 564

1.3-28.3

59 475

no. of indep rﬂns/R_int

transmssn

4362/0.019

0.999-0.510

128/374

0.94

0.0259

0.0547

5285/0.054

0.887-0640

0/358

1.24

0.0487

0.0886

2.26/-3.72

12 021/0.049

0.941-0.819

456/560

0.97

0.0235

0.0483

9793/0.060

0.928-0.743

103/530

0.92

0.0251

0.0466

no. of restraints/params

goodness of ﬁt on F²

R1 (I > 2σ(I))

wR2 (all rﬂns)

largest diff peak/hole (e Å^-3

)

1.03/-0.76

0.88/-0.75

0.99/-0.59

The ¹H NMR spectra of complexes 5b,c show at low

temperatures (-30 and -10 °C, respectively) the expected

three singlets (1:1:1) due to the MeO groups. When the

solutions are warmed (to 22 and 50 °C, respectively), the

spectra change to two singlets (2:1), suggesting [Pt(κ²-

Ar)BrL] a [Pt(κ¹-Ar)(µ-Br)L]₂equilibria.

bond because of the steric hindrance of the styrene phenyl

substituent, while in 6b it rotates even at low temperature.

1

The J_PtLdata can be related to the trans inﬂuence of the

ligand trans to L.^11,32The values found in this work allow the

deduction of a hierarchy of trans inﬂuences and the establish-

ment of geometries of some complexes. Thus, from ¹J_PtP(Hz),

Ar (8c1, 2092) > PPh₃(trans-7, 2770) > CO (8b, 3270) > SMe₂

(8a, 3634) ≈ bpy (11, 11 · 10, 3750) > Cl (10, 4283, 11 · 10,

4292) > O,O-acac (9, 4329). In addition, the expected lower

Halogen-bridged complexes 6 (Scheme 3) behave differently

1

in CDCl₃solutions. The H NMR spectrum of 6a shows the

two MeO singlets (2:1) expected for only one isomer with a

κ¹-Ar group, while in 6b a 4:1 mixture of isomers (probably

trans/cis) is observed at -30 °C. However, the ¹H and ¹³C NMR

spectra of 6c show a main isomer with three MeO singlets

(1:1:1) and minor amounts of other isomers. This means that

the κ¹-Ar group in 6c has restricted rotation around the C-Pt

1

value of J_PtLfor Pt(IV) complexes than for Pt(II) is evident

when ¹J_PtP(Hz) in 14 (2122) is compared with that in 10 (4283)

or 11 · 10 (4292). In the mixture obtained by reacting 1a with

PPh₃, the presence of 6d and trans-7 was evident because these

complexes have been isolated previously⁸or prepared in this

3516 Organometallics, Vol. 28, No. 12, 2009

Vicente et al.

diaqua platinum(IV) complex,⁴⁰both H₂O ligands are trans to

C. It is then reasonable to assume that, if the diastereoisomer

15c is discarded because of the strong τ(C-Ar/C-Ar), 15a is

the only complex at low temperature and the main component

of the mixture at room temperature where the equilibrium 15a

a 15b exists. Therefore, the water molecules in the main isomer

of 15 occupy the same positions as the replaced chloro ligands,

which is a reasonable result for a substitution reaction in a Pt(IV)

complex at room temperature.

All complexes containing a κ¹-Ar ligand show strong bands

in the ranges 1580-1500 and 1370-1350 cm^-1corresponding

to ν_asym(NO₂) and ν_sym(NO₂), respectively. We have reported

that the ν_sym(NO₂) band shifts to around 1200-1270 cm^-1when

the ligand is of the κ²-Ar type.^{4,7,9,13,22,30}However, this band

could not be assigned in the present complexes because in this

region some bands appear even in the absence of a κ²-Ar group.

In accordance with the crystal structure of 11 · 10, the bands

at 281 and 303 cm^-1in its IR spectrum and those at 281 and

305 cm^-1in PPN · 10 must be assigned to ν(Pt-Cl) trans to

Figure 17. Formation of dimers in complex 3 through Pt · · · π

stacking.

Chart 1

aryl (ν(Pt-Cl)_Ar) and trans to PPh₃(ν(Pt-Cl)_PPh) ligands,

3

respectively. The IR spectrum of 13 shows two bands at 377

and 365 cm^-1, assignable to ν(Pt-Cl) trans to O (ν(Pt-Cl)_O).

In accordance with this assignment, the bands at 366 and 316

(29) Vicente, J.; Arcas, A.; Mora, M.; Solans, X.; Font-Altaba, M. J.

Organomet. Chem. 1986, 309, 369. Vicente, J.; Arcas, A.; Borrachero,

M. V.; Hursthouse, M. B. J. Chem. Soc., Dalton Trans. 1987, 1655. Vicente,

J.; Arcas, A.; Borrachero, M. V.; Mol´ıns, E.; Miravitlles, C. J. Organomet.

Chem. 1989, 359, 127. Vicente, J.; Arcas, A.; Borrachero, M. V.; de

Goicoechea, M. L.; Lanfranchi, M.; Tiripicchio, A. Inorg. Chim. Acta 1990,

177, 247. Vicente, J.; Arcas, A.; Jones, P. G.; Lautner, J. J. Chem. Soc.,

Dalton Trans. 1990, 451. Vicente, J.; Bermu´dez, M. D.; Escribano, J.;

Carrillo, M. P.; Jones, P. G. J. Chem. Soc., Dalton Trans. 1990, 3083.

Vicente, J.; Arcas, A.; Borrachero, M. V.; Tiripicchio, A.; Tiripicchio-

Camellini, M. Organometallics 1991, 10, 3873. Vicente, J.; Arcas, A.;

Borrachero, M. V.; Mol´ıns, E.; Miravitlles, C. J. Organomet. Chem. 1992,

441, 487. Vicente, J.; Bermu´dez, M. D.; Carrio´n, F. J.; Jones, P. G. Chem.

Ber. 1996, 129, 1301. Vicente, J.; Bermu´dez, M. D.; Carrio´n, F. J.; Jones,

P. G. Chem. Ber. 1996, 129, 1395. Vicente, J.; Chicote, M. T.; Gonza´lez-

Herrero, P.; Gru¨nwald, C.; Jones, P. G. Organometallics 1997, 16, 3381.

Vicente, J.; Chicote, M. T.; Abrisqueta, M. D.; Jones, P. G. Organometallics

2000, 19, 2629. Vicente, J.; Arcas, A.; Ga´lvez-Lo´pez, M.-D.; Julia´-

Herna´ndez, F.; Bautista, D.; Jones, P. G. Organometallics 2008, 27, 1582.

(30) Vicente, J.; Chicote, M. T.; Martin, J.; Artigao, M.; Solans, X.;

Font-Altaba, M.; Aguilo´, M. J. Chem. Soc., Dalton Trans. 1988, 141.

(31) Vicente, J.; Arcas, A.; Ga´lvez-Lo´pez, M. D.; Jones, P. G. Orga-

nometallics 2004, 23, 3528.

work, respectively. The presence of cis-7 in this mixture was

proved by the observation of two doublets with platinum

1

satellites, whose J_PtPvalues of 2136 and 3991 Hz are the

expected values when PPh₃is trans to Ar and Cl, respectively.

In the mixture of isomers 8c1-3 it has been possible to assign

the resonances due to the nonisolated isomers (Scheme 4) using

the ¹J_PtPvalues 8c3 (2466 Hz, P trans to XyNC¹¹) < 8c2 (3791

Hz, P trans to Cl) associated with the trans inﬂuence of XyNC

> PPh₃> Cl. For complex 14, the facial arrangement of the Cl

(32) Pregosin, P. S. Coord. Chem. ReV. 1982, 44, 247.

1

(33) Hope, E. G.; Levason, W.; Powell, N. A. Inorg. Chim. Acta 1986,

115, 187. Pregosin, P. S.; Kunz, R. W. ³¹P and ¹³C NMR of Transition

Metal Phosphine Complexes; Springer-Verlag: New York, 1979; p 16.

Oberhauser, W.; Stampﬂ, T.; Bachmann, C.; Haid, R.; Langes, C.; Kopacka,

H.; Ongania, K. H.; Bruggeller, P. Polyhedron 2000, 19, 913. Oberhauser,

W.; Bachmann, C.; Stampﬂ, T.; Bruggeller, P. Inorg. Chim. Acta 1997,

256, 223.

(34) Crystallographic data were retrieved from the Cambridge Crystal-

lographic Database with Version 5.29 (November 2008 Updated January

and August 2008) on the basis of structures with crystallographic R factors

of less than 10%.

(35) Vicente, J.; Arcas, A. Coord. Chem. ReV. 2005, 249, 1135.

(36) Casas, J. M.; Falvello, L. R.; Fornie´s, J.; Mansilla, G. Polyhedron

1999, 18, 403. Hill, G. S.; Yap, G. P. A.; Puddephatt, R. J. Organometallics

1999, 18, 1408. Junicke, H.; Bruhn, C.; Kluge, R.; Serianni, A. S.; Steinborn,

D. J. Am. Chem. Soc. 1999, 121, 6232. Vedernikov, A. N.; Binﬁeld, S. A.;

Zavalij, P. Y.; Khusnutdinova, J. R. J. Am. Chem. Soc. 2006, 128, 82.

Janzen, M. C.; Jennings, M. C.; Puddephatt, R. J. Inorg. Chem. 2003, 42,

4553.

ligands is proposed on the basis of the J_PtPvalue (2122 Hz),

which is in the range reported for other Pt(IV) complexes

containing a phosphine trans to Cl.³³

At room temperature, the ¹H NMR spectrum of complex 15

shows 11 MeO resonances and no signal from the molecule of

H₂O, suggesting some type of ﬂuxional behavior. The MeO

signals are consistent with the presence of two diastereoisomers

in a 4:1 ratio because, according to the integrals, one signal

coincides accidentally with a signal of the other diastereoisomer.

When the temperature was decreased to -50 °C, the spectrum

showed six singlets of the same intensity for the MeO protons

and a broad singlet for the H₂O protons, which rules out

diastereoisomers 15d,e (Chart 1). A search of the Cambridge

Structural Database reveals a total of 11 crystal structures of

organometallic aqua complexes of platinum(IV)³⁴and, as in

Pd(II) complexes,³⁵whenever possible, the aqua ligand prefers

to be trans to C.³⁶Only in four complexes is an aqua ligand

not trans to C, but this is due to the enforced facial coordination

of a N-N-N,³⁷O-N-O,³⁸or N-O-N³⁹tridentate ligand.

The search also reveals that in the only crystal structure of a

(37) Prokopchuk, E. M.; Puddephatt, R. J. Can. J. Chem. 2003, 81, 476.

Canty, A. J.; Fritsche, S. D.; Jin, H.; Honeyman, R. T.; Skelton, B. W.;

White, A. H. J. Organomet. Chem. 1996, 510, 281.

(38) Appleton, T. G.; Byriel, K. A.; Hall, J. R.; Kennard, C. H. L.; Lynch,

D. E.; Sinkinson, J. A.; Smith, G. Inorg. Chem. 1994, 33, 444.

(39) Khusnutdinova, J. R.; Zavalij, P. Y.; Vedernikov, A. N. Organo-

metallics 2007, 26, 3466.

(40) Junicke, H.; Bruhn, C.; Muller, T.; Steinborn, D. Z. Anorg. Allg.

Chem. 1999, 625, 2149.

2,6-Dinitroaryl Pt(II) and Pt(IV) Complexes

Organometallics, Vol. 28, No. 12, 2009 3517

cm^-1in the IR spectrum of 12 must be assigned to ν(Pt-Cl)_O

and ν(Pt-Cl)_C, respectively. The X-ray diffraction study of 12

conﬁrms this assignment. In accordance with these asignments,

the three bands at 374, 307, and 293 cm^-1in the IR spectrum

of 14 are due to ν(Pt-Cl)_O, ν(Pt-Cl)_P, and ν(Pt-Cl)_C,

respectively. The chloro complex 17 shows a band assignable

Monodentate ligands afford complexes resulting from (1) bridge

splitting, [Pt(κ²-Ar)(X)L] (L ) MeCN, XyNC, CO), or (2)

cleavage of the Pt-O bond, [Pt(κ¹-Ar)(µ-X)L]₂(L ) 3-hexyne,

ethylene, styrene, PPh₃), depending on the steric hindrance of

the ligand. By using an excess of the ligand L, the complexes

[Pt(κ¹-Ar)BrL₂] (L ) MeCN, XyNC) were obtained. [Pt(κ¹-

Ar)(µ-Cl)(PPh₃)]₂has been used as the starting material for the

synthesis of [Pt(κ¹-Ar)Cl(PPh₃)L] (L ) PPh₃, SMe₂, CO,

XyNC), [Pt(κ¹-Ar)(acac-κ²O,O)(PPh₃)], [Pt(κ¹-Ar)Cl₂(PPh₃)]^-,

and [Pt(κ¹-Ar)(bpy)(PPh₃)]⁺. The platinum(IV) complexes (OC-

6-32)-[Pt(κ²-Ar)₂Cl₂], (OC-6-22)-[Pt(κ²-Ar)₂Cl₂], and fac-[Pt(κ²-

Ar)Cl₃(PPh₃)] have been obtained by chlorination of diaryl Pt(II)

complexes. The former reacts with AgClO₄to give (OC-6-32)-

[Pt(κ²-Ar)₂(OH₂)₂](ClO₄)₂and with PPh₃or AsPh₃to afford

Pt(II) complexes.

to ν(Pt-Cl)_Cat 293 cm^-1

.

The IR spectra of complexes 9 and 3 show a medium-intensity

band at 452 and 476 cm^-1, respectively, which has been assigned

to ν(PtO), in agreement with the chelating nature of the acac

ligand. The intensity and position of this band are similar to

those found in Me₄N[Pt(κ¹-Ar)₂(acac-κ²O,O)].⁷

Complex 15 shows a broad band in the region 3641-3605

cm^-1corresponding to ν(H₂O). The π-acceptor ability of CO

in complex 5c (ν(CO) 2124, 2116 cm^-1(sh)) is greater than

that in 8b (2134 cm^-1) because of the presence in the latter of

PPh₃.

Color of Complexes. In agreement with previous observa-

tions,^7,11,22,31complexes with a κ²-Ar ligand have intense color

(red (1a,b, 5a,b,c, 16, 17), dark pink (3), yellow (12), and orange

(13-15)) while for those complexes having only κ¹-Ar ligands,

the colors fade to pale yellow (2a-c, 4a,b, 6a, trans-7, 8a-c,

9, PPN · 10, 11 · 10, 11 · Cl) or pale pink (6b,c).

Acknowledgment. We thank Ministerio de Ciencia y

Tecnolog´ıa, FEDER (CTQ2007-60808/BQU, C-Consolider),

and Fundacio´n Se´neca (Comunidad Auto´noma de la Regio´n

de Murcia 04539/GERM/06: FS_CARM) for ﬁnancial sup-

port. M.D.G.-L. thanks the FS_CARM for a grant. Dr. R.

Herbst-Irmer gave valuable advice on the detwinning of

structures 3 and 5a.

Conclusions

Supporting Information Available: CIF ﬁles and tables of all

reﬁned and calculated atomic coordinates, anisotropic thermal

parameters, and bond lengths and angles for HAr, 2a · CH₂Cl₂, 2c,

3, 5a, trans-6b, 6c · CDCl₃, trans-7 · Et₂O, 8a,c, 9, 11 · 10 · 2CHCl₃,

12, 13, 16 · CDCl₃, and 17. This material is available free of charge

via the Internet at http://pubs.acs.org.

We describe the synthesis of the ﬁrst family of mono(ni-

troaryl) Pt(II) complexes, which have been obtained by hydro-

halogenation of cis-[Pt(κ²-Ar)(κ¹-Ar)(OH₂)]. The products of

this reaction, [Pt(κ²-Ar)(µ-X)]₂(X ) Cl, Br), have been used

to prepare the complexes [Pt(κ¹-Ar)X(L^∧L)] or [Pt(κ²-Ar)(acac-

κ²-O,O)] with bidentate neutral or anionic ligands, respectively.

OM9001582

Article Doi

Mono(2,6-dinitroaryl)platinum(II) and Mono- and Bis(2,6-dinitroaryl) platinum(IV) Complexes

DOI: 10.1021/om9001582

Source and publish data:

Authors:

Article abstract of DOI:10.1021/om9001582

Full text of DOI:10.1021/om9001582

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