Synthesis and reactivity toward isonitriles of (2-aminoaryl)palladium(II) complexes

Article abstract of DOI:10.1021/om0104971

The synthesis and reactivity towards isonitriles of (2-aminoaryl)palladium(II) complexes were studied. The NMR spectra of the complexes was found in agreement with the proposed structures. The structure of the cation of 9a·CH₂Cl₂ showed an iodine atom bridging two palladium centres, with every palladium atom bonded to both a terminal isonitrile and a chelating ligand.

Full text of DOI:10.1021/om0104971

272
Organometallics 2002, 21, 272-282
Syn th esis a n d Rea ctivity tow a r d Ison itr iles of
(2-Am in oa r yl)p a lla d iu m (II) Com p lexes
J ose´ Vicente,*,† J ose´-Antonio Abad,*,† Andrew D. Frankland, and
J oaqu´ın Lo´pez-Serrano
Grupo de Quı´mica Organometa´lica, Departamento de Qu´ımica Inorga´nica, Facultad de
Quı´mica, Universidad de Murcia, Aptdo. 4021, E-30071 Murcia, Spain
M. Carmen Ram´ırez de Arellano*,‡
Departamento de Quı´mica Orga´nica, Universidad de Valencia, 46100 Valencia, Spain
Peter G. J ones*,§
Institut fu¨r Anorganische und Analytische Chemie, Technische Universita¨t Braunschweig,
Postfach 3329, 38023 Braunschweig, Germany
Received J une 11, 2001
Mixtures of “Pd(dba)2” (dba ) dibenzylideneacetone) and 2,2′-bipyridine (bpy; 1:2) or
N,N,N′,N′-tetramethylethylenediamine (tmeda; 1:1) react with 2-bromo-4-nitroaniline to give
[Pd{C6H3NH2-2-NO2-5}Br(N-N)] (N-N ) bpy (1b), tmeda (1b′)). Reactions of 2-iodoaniline
with mixtures of “Pd(dba)2” and isonitriles RNC (R ) C6H3Me2-2,6 (Xy), 2:1:2 molar ratios;
R ) tBu, 2.9:1:2 molar ratios) result in the formation of the complexes [Pd{κ2C,N-C(dNXy)-
C6H4NH2-2}I(CNXy)] (2a ) and trans-[Pd{C(dNtBu)C6H4NH2-2}I(CNtBu)2] (3a *). The reac-
tions of [Pd{C6H4NH2-2}I(bpy)] and 1b′ with RNC give the complexes trans-[Pd{C(d
t
NR)C6H3NH2-2-Y-5}}X(CNR)2] (Y ) H, X ) I, R ) Xy (3a ), Bu (3a *); Y ) NO2, X ) Br, R
) Xy (3b), tBu (3b*)). Complexes 3 react with Tl(TfO) (TfO ) CF3SO3) to give decomposition
products, with the exception of 3a , which gives the cyclopalladated complex cis-[Pd{κ2C,N-
C(dNXy)C6H4NH2-2}(CNXy)2]TfO (4a ). Complex 2a or 3 reacts with Tl(TfO) in the presence
of the corresponding ligand, L or L2, to give the cationic complex [Pd{C(dNR)C6H3NH2-2-
t
t
Y-5}(CNR)L2]TfO (L ) BuNC, Y ) H (5a *), NO2 (5b*); L2 ) bpy, Y ) H, R ) Xy (6a ), Bu
(6a *)). When L ) PPh3, the resulting complexes trans-[Pd{C(dNR)C6H3NH2-2-Y-5}(CN-
tBu)2(PPh3)]TfO (Y ) H (7a *), NO2 (7b*)) decompose easily to the Pd(I) complex [Pd2(CN-
tBu)4(PPh3)2](TfO)2 (8). The reaction of 2a with Tl(TfO) affords [{Pd[κ2C,N-C(dNXy)C6H4-
NH2](CNXy)}2(µ-I)]TfO (9a ), and that with a mixture of bpy and Tl(TfO) in acetone with
subsequent bubbling of CO through the solution gives [Pd(R)(CNXy)(bpy)](TfO)2 (10), where
R is 2-(xylylamino)-3-xylylquinazolinium-4-yl. The crystal structures of 2a , 3a , 4a , 6a , 8,
9a ‚CH2Cl2, and 10‚1.5CH2Cl2 have been determined by X-ray diffraction studies. Some
3
hydrogen bond interactions (Csp -H‚‚‚Pd, N-H‚‚‚π-arene, N-H‚‚‚I-Pd; eight-membered
rings ‚‚‚O-S-O‚‚‚H-N-C-C-H‚‚‚ and ‚‚‚I-Pd-N-H‚‚‚I-Pd-N-H‚‚‚) lead to interesting
supramolecular structures.
In tr od u ction
oxygen,6 or carbon-phosphorus bonds.7 In particular,
(2-aminophenyl)palladium species are intermediates in
the palladium-catalyzed formation of nitrogen-contain-
ing heterocycles from o-iodo- or o-bromoanilines and, for
example, alkynes,8 dienes,9,10 and vinyl cyclopropanes
Arylpalladium complexes participate in many pal-
ladium-catalyzed organic reactions involving carbon-
carbon1-3 or carbon-heteroatom bond formation: for
example, the formation of carbon-nitrogen,3-5carbon-
† E-mail: J .V., jvs@um.es; J .-A.A., jaab@um.es. Web: http://
www.scc.um.es/gi/gqo.
(4) Wolfe, J . P.; Wagaw, S.; Marcoux, J .-F.; Buchwald, S. L. Acc.
Chem. Res. 1998, 31, 805. Goodson, F. E.; Hauck, S. I.; Hartwig, J . F.
J . Am. Chem. Soc. 1999, 121, 7527. Bei, X. H.; Uno, T.; Norris, J .;
Turner, H. W.; Weinberg, W. H.; Guram, A. S.; Petersen, J . L.
Organometallics 1999, 18, 1840. Huang, J .; Grasa, G.; Nolan, S. P.
Org. Lett. 2000, 1, 1307. Old, D. W.; Harris, M. C.; Buchwald, S. L.
Org. Lett. 2000, 1, 1403. Stauffer, S. R.; Lee, S.; Stambuli, J . P.; Hauck,
S. I.; Hartwig, J . F. Org. Lett. 2000, 1, 1423.
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(6) Mann, G.; Incarvito, C.; Rheingold, A. L.; Hartwig, J . F. J . Am.
Chem. Soc. 1999, 121, 3224. Aranyos, A.; Old, D. W.; Kiyomori, A.;
Wolfe, J . P.; Sadighi, J . P.; Buchwald, S. L. J . Am. Chem. Soc. 1999,
121, 4369.
‡ Corresponding author regarding the X-ray diffraction studies of
compounds 2a , 4a , 6a , 9a ‚CH2Cl2, and 10‚1.5CH2Cl2. E-mail:
M.Carmen.Ramirezdearellano@UV.es.
§ Corresponding author regarding the X-ray diffraction study of
compounds 3a and 8. E-mail: p.jones@tu-bs.de.
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10.1021/om0104971 CCC: $22.00 © 2002 American Chemical Society
Publication on Web 12/20/2001

(2-Aminoaryl)palladium(II) Complexes
Organometallics, Vol. 21, No. 2, 2002 273
and cyclobutanes,11 as well as in intramolecular cascade
cyclizations.12 The palladium-catalyzed synthesis of
2-aryl- and 2-vinyl-4H-3,1-benzoxazin-4-ones from 2-
iodoaniline, carbon monoxide, and the appropriate
complexes. Moreover, di-,20,25,26,32,33,42,54 tri-,20,55 and
polyinsertion reactions, which are relevant in the pal-
ladium-mediated, screw-sense-selective polymerization
of isonitriles, have been reported.54,56,57 In some cases,
these insertions can be followed by a transformation of
the resultant ligand to give, for example, a σ-bonded
vinylketenimine,50 a coordinated â-keto imino frag-
ment,25 or, after a depalladation process, organic com-
pounds.24-26,36,38-41,58 We have reported the synthesis
of a highly functionalized ketenimine by the reaction
of a (2,3,4-trimethoxy-6-formylphenyl)palladium com-
plex with 2,6-dimethylphenyl isocyanide.43 The imidoyl
complexes reported have been prepared (i) by
reacting isonitriles with alkyl,19,20,23,25,27-30,39,55,59
aryl,20,30,35,37,38,40,42-44,55 alkynyl,28,32,33,56 or other orga-
nopalladium complexes,49,51,52,59 (ii) via transmetalation
reactions involving an organosodium52 or an organo-
mercury compound60 and a palladium isonitrile complex,
and (iii) by the thermal rearrangement of an organo-
(isonitrile)palladium complex.46,47,61 In this paper, we
report the synthesis of imidoyl complexes involving (i)
insertion reactions of isonitriles with (2-aminoaryl)-
palladium complexes or (ii) oxidative addition reactions
of 2-iodoaniline or 2-bromo-4-nitroaniline with Pd-
(CNR)2 (R ) Xy ) 2,6-dimethylphenyl, tBu). This
method has only been used with a few alkylpalladium
complexes, and the results were different from those we
organic halides or triflates has been reported.13
A
palladium-catalyzed domino process to give 1-benz-
azepines from 2-iodoaniline and homoallylic alcohols has
also been developed.14 These results have encouraged
us to isolate (2-aminoaryl)palladium complexes and to
study their reactivity. We have reported previously the
synthesis of (2-amino-5-nitrophenyl)palladium com-
plexes via oxidative addition of the corresponding bro-
moarene to [Pd(PPh3)4].15 More recently we have pre-
pared (2-aminophenyl)palladium complexes by the
oxidative addition of 2-iodoaniline to Pd(0) species and
studied their reactivity toward carbon monoxide and
oxygen.16,17 In this context, we wish to report here on
the synthesis of new (2-aminoaryl)palladium complexes
and a study of their reactivity with isonitriles.
Isonitriles usually react with organopalladium com-
plexes to give imidoyl compounds. Such insertion
reactions have been observed with alkyl-,18-31 al-
kynyl-,28,32-35 aryl-,36-48 and other49-53 organopalladium
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274 Organometallics, Vol. 21, No. 2, 2002
Vicente et al.
report here.59 We have recently used the same method
of synthesis starting from 2-ROC6H4I (R ) H, C(O)-
Me).62
yellow-green solid. Yield: 275 mg, 65%. Dec pt: 160 °C. IR
(Nujol, cm-1): ν 3166 (NH), 3140 (NH), 2170 (CtN), 1640 (Nd
1
C). H NMR (200 MHz, CDCl3): δ 8.16 (d, J H,H ) 11 Hz, 1 H),
7.5-7.0 (several m, aromatics, 4 H), 6.96 (d, J H,H ) 11 Hz, 2
H), 6.75 (d, J H,H ) 11 Hz, 2 H), 6.27 (t, J H,H ) 11 Hz, 1 H),
5.44 (s, NH2, 2 H), 2.24 (s, 2Me, 6H), 2.21 (s, 2Me, 6H). 13C-
{1H} NMR (50 MHz, CDCl3): δ 175.0 (CdN), 152.2 (CN), 144.1,
142.9, 134.0, 131.7 (C-H), 128.8 (C-H), 128.2 (C-H), 127.5
(C-H), 127.4 (C-H), 127.0, 126.8 (C-H), 124.6 (C-H), 123.7
(C-H), 19.2 (Me), 18.6 (Me). Anal. Calcd for C24H24IN3Pd: C,
49.04; H, 4.12; N, 7.15. Found: C, 49.33; H, 4.06; N, 7.18.
Single crystals of 2a were grown by slow diffusion of n-hexane
into solutions of 2a in CH2Cl2.
Syn t h esis of tr a n s-[P d {C(dNt Bu )C6H 4NH 2-2}I(CN-
tBu )2] (3a *). Meth od A. “Pd(dba)2” (360 mg, 0.63 mmol) and
tBuNC (138 µL, 1.3 mmol) were mixed in toluene (30 mL) at
0 °C under nitrogen and stirred for 5 min. 2-Iodoaniline (390
mg, 1.8 mmol) was then added, and the mixture was warmed
slowly to room temperature and stirred for a further 15 h. The
solvent was evaporated in vacuo, CH2Cl2 (20 mL) was added,
and the resulting suspension was filtered through Celite. The
yellow solution was evaporated to dryness, the residue was
washed with Et2O and filtered, and the solid was washed with
Et2O and n-hexane and air-dried, giving 3a * as a yellow solid.
Yield: 210 mg, 81% with respect to isonitrile.
Exp er im en ta l Section
C, H, N, and S analyses, melting point measurements,
infrared and NMR spectra, and purification of solvents were
carried out as described previously.63 The complex “Pd(dba)2”
([Pd2(dba)3]‚dba; dba ) dibenzylideneacetone) was prepared
by following described procedures.1,64 The compound [Pd{C6H4-
NH2-2}I(bpy)] (1a ) was prepared as reported previously.17
Preparative TLC separations were carried out on silica 60
AC.C 70-200 µm.
Syn th esis of [P d {C6H3NH2-2-NO2-5}Br (bp y)] (1b). “Pd-
(dba)2” (160 mg, 0.28 mmol) and bpy (2,2′-bipyridine) (87 mg,
0.55 mmol) were mixed in toluene (10 mL) under nitrogen and
stirred for 15 min. 2-Bromo-4-nitroaniline was then added and
the resulting mixture stirred at 130 °C in a silicone oil bath
for a few minutes until the red color disappeared. The hot bath
was then substituted by a cooled water bath, and solvents were
removed in vacuo. The residue was extracted with acetone (15
cm3), and the extracts were filtered through anhydrous
magnesium sulfate. The magnesium sulfate was washed with
hot acetone (3 × 5 cm3), and the washing liquors were added
to the extracts. The resulting solution was evaporated almost
to dryness. Addition of Et2O precipitated a yellow solid which
was washed with Et2O and dried in a current of air, giving
yellow 1b. Yield: 65 mg, 50%. IR (Nujol, cm-1): ν 3438 (NH),
Meth od B. tBuNC (42 µL, 0.37 mmol) was added to a
solution of 1a (60 mg, 0.12 mmol) in CH2Cl2 (10 mL) at room
temperature. The pale yellow solution was stirred for 10 min
and the solvent evaporated to dryness. Addition of n-hexane
(10 mL) precipitated a solid which was filtered, washed with
n-hexane, and air-dried to give 3a *. Yield: 51 mg, 70%. Mp:
149 °C. IR (Nujol, cm-1): ν 3403 (NH), 3203 (NH), 2187 (Ct
1
4
3326 (NH). H NMR (300 MHz, (CD3)2CO): δ 9.16 (d, J H,H
)
4 Hz, 1 H, H6), 8.12 (d, J H,H ) 2 Hz, 2 H, bpy), 8.27 (m, 2 H,
bpy), 7.88-7.45 (several m, 6 H, bpy and aryl), 6.4 (b s, 2 H
NH2). Compound 1b could not be isolated as an analytically
pure compound (see Discussion).
1
3
N). H NMR (300 MHz, CDCl3): δ 8.46 (dd, J H,H ) 8 Hz,
4J H,H ) 1.5 Hz, 1 H, H6), 7.01 (ddd, J H,H ) 8 Hz, J H,H ) 8
3
3
4
3
Hz, J H,H ) 1.5 Hz, 1 H, H4 or H5), 6.72 (ddd, J H,H ) 8 Hz,
Syn th esis of [P d {C6H3NH2-2-NO2-5}Br (tm ed a )] (1b′).
“Pd(dba)2” (200 mg, 0.34 mmol) and N,N,N′,N′-tetramethyl-
ethylenediamine (tmeda; 40 mg, 0.34 mmol) were mixed in
toluene (10 mL) under nitrogen, and the mixture was stirred
for 15 min. 2-Bromo-4-nitroaniline (150 mg, 0.69 mmol) was
then added, and the mixture was heated slowly until its color
turned from red to orange-yellow. The solvent was removed
in vacuo and the residue treated with CH2Cl2 (12 cm3) and
filtered through Celite. The resulting yellow solution was
evaporated to dryness and Et2O added to precipitate the
compound, which was filtered, washed with Et2O and n-
hexane, and air-dried. This solid was purified by preparative
TLC with CH2Cl2/Et2O (3:1), Rf ) 0.46. Yield: 92 mg, 60%.
Mp: 192 °C. IR (Nujol, cm-1): ν 3440 (NH), 3316 (NH). 1H
3J H,H ) 8 Hz, J H,H ) 1.5 Hz, 1 H, H4 or H5), 6.56 (dd, J H,H
)
4
3
4
8 Hz, J H,H ) 1.5 Hz, 1 H, H3), 6.02 (s, 2H NH2), 1.62 (s, 9 H,
3Me), 1.37 (s, 18 H, 6Me). Anal. Calcd for C21H33IN4OPd: C,
43.88; H, 5.79; N, 9.75. Found: C, 44.20; H, 5.67; N, 9.57.
Syn th esis of tr a n s-[P d {C(dNtBu )C6H4NH2-2}I(CNXy)2]
(3a ). XyNC (67 mg, 0.51 mmol) was added to a solution of 2a
(300 mg, 0.51 mmol) in CH2Cl2 (15 mL) at 0 °C, and the
resulting suspension was warmed slowly to room temperature
and stirred overnight. The solvent was removed in vacuo and
Et2O added to give 3a as a pale yellow solid. Yield: 293 mg,
80%. Dec pt: 140 °C. IR (Nujol, cm-1): ν 3450 (NH), 3374 (NH),
3290 (NH), 2180 (CtN). 1 H NMR (300 MHz, CDCl3, -60 °C):
δ 8.76 (d, 3J H,H ) 8 Hz, 1 H, H6 ortho to imine group), 7.4-6.9
3
4
(several m, 10 H, Xy and H4 or H5, 6.85 (t, J H,H ) 8 Hz, 1 H,
NMR (300 MHz, (CD3)2CO): δ 7.87 (d, J H,H ) 2.5 Hz, 1 H,
H5 or H4), 6.72 (d, 3J H,H ) 8 Hz, 1 H, H3), 6.3 (vb s, 2 H, NH2),
2.23 (s, 12 H, Me), 2.16 (s, 6 H, Me). 13C{1H} NMR (75 MHz,
CDCl3, room temperature): δ 179.15 (C), 149.10 (C), 145.63
(C), 144.01 (b C), 138.06 (b, CH), 135.87 (C), 135.70 (C), 130.40
(CH), 129.89 (CH), 128.07 (CH), 127.96 (CH), 127.00 (C),
125.59 (b, C), 123.51 (CH), 116.05 (b, C-H), 115.32 (b, C-H),
19.04 (s, Me), 18.64 (s, Me). Anal. Calcd for C33H33IN4Pd: C,
55.13; H, 4.63; N, 7.79. Found: C, 55.39; H, 4.51; N, 7.87.
Single crystals of 3a were grown by slow diffusion of n-hexane
into solutions of 3a in CH2Cl2.
Syn th esis of tr a n s-[P d {C(dNXy)C6H3NH2-2-NO2-5}Br -
(CNXy)2] (3b). Meth od A. Complex 1b (60 mg, approximately
0.13 mmol) was reacted with XyNC (70 mg, 0.38 mmol) in
acetone (15 mL) for 10 min. The solvent was evaporated in
vacuo and Et2O (10 mL) added, causing the precipitation of a
solid which was filtered, washed with Et2O and n-hexane, and
air-dried to give yellow 3b. Yield: 68 mg, 75%.
H6), 7.59 (dd, 3J H,H ) 8.5 Hz, 4J H,H ) 2.5 Hz, 1 H, H4), 6.30 (d,
3J H,H ) 8.5 Hz, 1 H, H3), 5.76 (b s, 2 H NH2), 3.15-2.5 (several
m, 4H, CH2), 2.69 (s, 3 H, Me), 2.67 (s, 3 H, Me), 2.60 (s, 3 H,
Me), 2.47 (s, 3 H, Me). Anal. Calcd for C12H21BrN4O2Pd: C,
32.78; H, 4.81; N, 12.74. Found: C, 33.23; H, 4.66; N, 12.51.
Syn th esis of [P d {K2C,N-C(dNXy)C6H4NH2-2}I(CNXy)]
(2a ). Pd(dba)2 (400 mg, 0.70 mmol) and XyNC (Xy ) C6H3-
Me2-2,6; 184 mg, 1.40 mmol) were mixed in toluene (60 mL)
at -5 °C and stirred for 5 min under N2. Then, C6H4NH2I-2
(302 mg, 1.40 mmol) was added and the temperature of the
reaction mixture maintained for a further 4 h. The reaction
mixture was stirred for 3 days more at room temperature. The
resulting suspension was then evaporated to dryness, the
residue was extracted with CH2Cl2, and the extracts were
filtered through anhydrous MgSO4. The green-brown solution
was concentrated and Et2O added to precipitate 2a as a pale
(62) Vicente, J .; Abad, J . A.; Fo¨rtsch, W.; J ones, P. G.; Fischer, A.
K. Organometallics 2001, 20, 2704.
(63) Vicente, J .; Abad, J . A.; Gil-Rubio, J .; J ones, P. G. Organome-
tallics 1995, 14, 2677.
(64) Yatsimirsky, A. K.; Kazankov, G. M.; Ryabov, A. D. J . Chem.
Soc., Perkin Trans. 2 1992, 1295.
Meth od B. 3b was similarly prepared from complex 1b′ (60
mg, 0.14 mmol) and XyNC (54 mg, 0.41 mmol). Yield: 85 mg,
87%. Mp: 160 °C. IR (Nujol, cm-1): ν 3346 (NH), 2184 (Ct
1
4
N). H NMR (300 MHz, CDCl3): δ 9.62 (d, J H,H ) 3 Hz, 1 H,
3
4
H6), 8.06 (dd, J H,H ) 9 Hz, J H,H ) 3 Hz, 1 H, H4), 7.3 (vb s,

(2-Aminoaryl)palladium(II) Complexes
2 H, NH2), 7.28-6.9 (several m, 9 H, XyNC), 6.67 (d, J H,H
Organometallics, Vol. 21, No. 2, 2002 275
3
)
Et2O added to precipitate 2a as a pale yellow solid. Yield: 179
mg, 91%. Dec pt: 165 °C. IR (Nujol, cm-1): ν 3452 (NH), 3340
(NH), 2194 (CtN). 1H NMR (200 MHz, CDCl3): δ 8.69 (d, J H,H
) 8 Hz, 1 H), 8.24 (m, 2 H), 7.6-6.7 (several m, 15 H), 6.35 (b
s, 2 H, NH2), 2.23 (s, 6 H, 2Me), 1.91 (s, 6 H, 2Me). 13C{1H}
NMR (75 MHz, CDCl3) δ 179.04 (CdN), 154.79, 150.24 (C-
H), 148.95, 147.05, 141.64 (b, C-H), 136.10 (C-H), 135.55
(CN), 131.58 (C-H), 130.83 (C-H), 128.48 (C-H), 128.33 (C-
H), 127.48 (C-H), 126.71, 123.97 (C-H), 121.36, 117.64,
116.76 (C-H), 116.09 (C-H), 18.99 (Me), 18.62 (Me). 19F NMR
(282 MHz, CDCl3): δ -77.8 (s, CF3). Anal. Calcd for C35H32F3-
N5O3PdS: C, 54.87; H, 4.21; N, 9.14; S, 4.18. Found: C, 54.34;
H, 4.27; N, 8.76; S, 4.23. Single crystals of 6a were grown by
slow diffusion of n-hexane into solutions of 6a in CH2Cl2.
9 Hz, 1 H, H3), 2.24 (s, 12 H, 4Me), 2.16 (s, 6 H, 2Me). Anal.
Calcd for C33H32BrN5O2Pd: C, 55.28; H, 4.50; N, 9.77. Found:
C, 54.94; H, 4.39; N, 9.54.
Syn th esis of tr a n s-[P d {C(dNtBu )C6H3NH2-2-NO2-5}Br -
(CNtBu )2] (3b*). This yellow complex was similarly prepared
t
from 1b (60 mg, approximately 0.13 mmol) and BuNC (42 µL,
0.38 mmol) (method A) or from 1b′ (60 mg, 0.14 mmol) and
tBuNC (46 µL, 0.41 mmol) (method B). Yield: 53 mg, 74% and
66 mg, 84%, respectively. Mp: 156 °C. IR (Nujol, cm-1): ν 3336
(NH), 2192 (CtN). 1H NMR (300 MHz, CDCl3): δ 9.22 (d, 4J H,H
3
) 3 Hz, 1 H, H6), 7.92 (dd, J H,H ) 9 Hz,4J H,H ) 3 Hz, 1 H,
3
H4), 6.87 (s, 2 H, NH2), 6.53 (d, J H,H ) 9 Hz, 1 H, H3), 1.62
(s, 9 H, 3Me), 1.39 (s, 18 H, 6Me). Anal. Calcd for C21H32
-
Syn th esis of [P d {C(dNtBu )C6H4NH2-2}(CNtBu )(bp y)]-
TfO (6a *). bpy (34 mg, 0.19 mmol) and Tl(TfO) (68 mg, 0.21
mmol) were added to a solution of complex 3a * (100 mg, 0.17
mmol) in acetone (10 mL). The resulting suspension was
stirred for 15 min and then filtered through Celite. The filtrate
was evaporated to dryness and the residue triturated with
Et2O (10 mL). The resulting solid was filtered, washed with
Et2O (3 × 3 mL), and air-dried to give 6a * as a yellow solid.
Yield: 100 mg, 86%. Mp: 132 °C. ΛM ) 135 Ω-1 cm2 mol-1. IR
(Nujol, cm-1): ν 3370 (NH), 2212 (CtN). 1 H NMR (300 MHz,
CDCl3): δ 8.7-6.5 (several m, 12 H), 6.89 (s, 2H, NH2), 1.63
(s, 9 H, 3Me), 1.58 (s, 9 H, 3Me). Anal. Calcd for C27H42F3N5O3-
PdS: C, 48.40; H, 4.81; N, 10.45; S, 4.79. Found: C, 48.63; H,
4.91; N, 10.60; S, 4.75.
BrN5O2Pd: C, 44.03; H, 5.63; N, 12.23 found: C, 44.05; H, 5.94;
N, 11.99.
Syn th esis of cis-[P d{K2C,N-C(dNXy)C6H4NH2-2}(CNXy)2]-
TfO (4a ). Tl(TfO) (100 mg, 0.28 mmol) was added to a solution
of 3a (200 mg, 0.28 mmol) in CH2Cl2 (10 mL) at 0 °C. The
resulting suspension was warmed slowly to room temperature
and stirred overnight. The mixture was filtered through
MgSO4, the solvent removed in vacuo, and n-hexane added to
precipitate 4a as an orange solid. Yield: 151 mg, 73%. Dec pt:
105 °C. IR (Nujol, cm-1): ν 3426 (NH), 3372 (NH), 3305 (NH),
2178 (CtN). ΛM ) 144 Ω-1 cm2 mol-1
.
1H NMR (300 MHz,
3
CDCl3): δ 8.09 (d, J H,H ) 7.5 Hz, 1 H, ortho to imine group),
7.75 (d, 3J H,H ) 7.5 Hz, 1 H, ortho to NH2 group), 7.44 (t, 3J H,H
) 7.5 Hz, 1 H, H4 or H5), 7.36-7.12 (m, 3 H, 3H4 of Xy), 7.05
3
3
(d, J H,H ) 8 Hz, 4 H, 2H3 of Xy), 6.78 (d, J H,H ) 8 Hz, 2 H,
H3 of Xy), 6.72 (b s, 2 H, NH2), 6.33 (t, 3J H,H ) 7.5 Hz, 1 H, H5
or H4), 2.29 (b s, 12 H, 4Me), 2.20 (s, 6 H, 2Me). At -50 °C
the broad signal corresponding to 4Me changed to two singlets
at 2.33 (2 Me) and 2.27 (2 Me) ppm. Anal. Calcd for
Syn th esis of tr a n s-[P d {C(dNtBu )C6H4NH2-2}(CNtBu )2-
(P P h 3)]TfO (7a *). PPh3 (45 mg, 0.16 mmol) and Tl(TfO) (61
mg, 0.16 mmol) were added to a solution of complex 3a * (94
mg, 0.16 mmol) in acetone (15 mL). The resulting suspension
was stirred for 15 min and then filtered through Celite. The
filtrate was evaporated to dryness and the residue triturated
with Et2O (10 mL). The resulting solid was filtered, washed
with Et2O (33 mL) and n-hexane, and air-dried to give 7a * as
a yellow solid. Yield: 128 mg, 92%. IR (Nujol, cm-1): ν 3394
(NH), 2198 (CtN). 1H NMR (200 MHz, CDCl3): δ 7.49 (dd,
C
34H33F3N4O3PdS: C, 55.10; H, 4.49; N, 7.56; S, 4.33. Found:
C, 54.55; H, 4.56; N, 7.63; S, 4.14. Single crystals of 4a were
grown by slow diffusion of n-hexane into solutions of 4a in
CH2Cl2.
Syn t h esis of [P d {C(dNt Bu )C6H 4NH 2-2}(CNt Bu )3]TfO
t
(5a *). BuNC (27 µL, 0.17 mmol) and Tl(TfO) (62 mg, 0.17
4
3J H,H ) 8 Hz, J H,H ) 1.5 Hz, 1 H, H6), 7.62-7.31 (m, 15 H,
mmol) were added to a solution of 3a * (100 mg, 0.17 mmol) in
acetone (10 mL). The resulting suspension was stirred for 15
min and then filtered through Celite. The filtrate was evapo-
rated to dryness and Et2O (10 mL) added, giving a solid which
was filtered, washed with Et2O (3 × 3 mL) and n-hexane (3 ×
3 mL), and air-dried to give 5a * as a yellow solid. Yield: 80
mg, 68%. Mp: 110 °C. IR (Nujol, cm-1): ν 3432 (NH), 3320
3
3
4
PPh3), 7.09 (ddd, J H,H ) 8 Hz, J H,H ) 8 Hz, J H,H ) 1.5 Hz, 1
3
3
4
H, H4 or H5), 6.76 (ddd, J H,H ) 8 Hz, J H,H ) 8 Hz, J H,H
)
3
4
1.5 Hz, 1 H, H4 or H5), 6.67 (dd, J H,H ) 8 Hz, J H,H ) 1.5 Hz,
1 H, H3), 5.92 (s, 2 H NH2), 1.60 (s, 9 H, 3Me), 1.13 (s, 18 H,
6Me). 31P NMR (121 MHz, CDCl3): δ 14.38 (s, PPh3). These
NMR spectra show small signals due to the presence of
impurities, including 8 (see Discussion). These impurities could
not be removed.
(NH), 2280 (CtN). ΛM ) 142 Ω-1 cm2 mol-1
.
1H NMR (300
3
4
MHz, CDCl3): δ 7.99 (dd, J H,H ) 8 Hz, J H,H ) 1 Hz, 1 H,
Syn th esis of tr a n s-[P d {C(dNtBu )C6H3NH2-2-NO2-5}-
(CNtBu )2(P P h 3)]TfO (7b*). This yellow complex was simi-
larly prepared from 3b* (60 mg, 0.11 mmol), PPh3 (28 mg, 0.11
mmol), and Tl(TfO) (37 mg, 0.11 mmol). Yield: 75 mg, 79%.
3
3
4
H6), 7.06 (ddd, J H,H ) 8 Hz, J H,H ) 8 Hz, J H,H ) 1 Hz, 1 H,
H4 or H5), 6.74 (ddd, 3J H,H ) 8 Hz, 3J H,H ) 8 Hz, 4J H,H ) 1 Hz,
3
4
1 H, H4 or H5), 6.62 (dd, J H,H ) 8 Hz, J H,H ) 1.5 Hz, 1 H,
H3), 5.98 (s, 2H NH2), 1.61 (s, 9 H, 3Me), 1.57 (s, 9 H, 3Me),
1.42 (s, 18 H, 6Me). Anal. Calcd for C27H32F3N5O3PdS: C,
47.68; H, 6.62; N, 10.30; S, 4.71. Found: C, 47.73; H, 6.48; N,
10.43; S, 4.58.
1
IR (Nujol, cm-1): ν 3392 (NH), 2208 (CtN). H NMR (200
MHz, CDCl3): δ 9.15 (d, 4J H,H ) 3 Hz, 1 H, H6), 7.95 (dd, 3J H,H
4
) 9 Hz, J H,H ) 3 Hz, 1 H, H4), 7.60-7.45 (m, 17 H, PPh3
+
3
Syn t h esis of [P d {C(dNt Bu )C6H 3NH 2-2-NO2-5}(CN-
tBu )3]TfO (5b*). The yellow complex 5b* was similarly
prepared from 3b* (37 mg, 0.034 mmol), tBuNC (7.5 µL, 0.064
mmol), and Tl(TfO) (23 mg, 0.064 mmol). Yield: 41 mg, 84%.
Mp: 135 °C. ΛM ) 137 Ω-1 cm2 mol-1. IR (Nujol, cm-1): ν 3342
(NH), 2210 (CtN). 1H NMR (300 MHz, CDCl3): δ 8.90 (d, 4J H,H
) 2.5 Hz, 1 H, H6), 7.94 (dd, 3J H,H ) 9 Hz, 4J H,H ) 2.5 Hz, 1 H,
NH2), 6.93 (d, J H,H ) 9 Hz, 1 H, H3), 1.64 (s, 9 H, 3Me), 1.11
(s, 18 H, 6Me). 31P NMR (121 MHz, CDCl3): δ 14.47 (s, PPh3).
These NMR spectra contain small signals due to the presence
of impurities, including 8 (see Discussion). These impurities
could not be removed.
Syn th esis of [P d 2(CNtBu )4(P P h 3)2](TfO)2 (8). A sample
of 7a * or 7b* was dissolved in the minimum amount of acetone
or CH2Cl2. The solution was left standing for 24 h at room
temperature. Et2O was slowly added until a turbidity was
observed; the mixture was left overnight in the refrigerator.
In this way crystals of 8 were obtained, some of them suitable
for X-ray determination studies. IR (Nujol, cm-1): ν 2190 (Ct
3
H4), 7.62 (s, 2 H, NH2), 6.86 (d, J H,H ) 9 Hz, 1 H, H3), 1.63
(s, 9 H, 3Me), 1.57 (s, 9 H, 3Me), 1.44 (s, 18 H, 6Me). Anal.
Calcd for C32H51F3N6O5PdS: C, 44.72; H, 5.69; N, 11.59; S,
4.42. Found: C, 44.75; H, 6.05; N, 11.34; S, 4.93.
Syn th esis of [P d {C(dNXy)C6H4NH2-2-(CNXy)}(bp y)]-
TfO (6a ). Bpy (40 mg, 0.26 mmol) and Tl(TfO) (95 mg, 0.27
mmol) were added to a solution of 2a (150 mg, 0.26 mmol) in
CH2Cl2 (12 mL). The resulting suspension was stirred for 3 h
and then filtered. The filtrate was evaporated to dryness and
1
N). H NMR (300 MHz, CDCl3): δ 7.6-7.4 (m, 30 H, 2PPh3),
1.30 (s, 36 H, 12Me), 31P NMR (121 MHz, CDCl3): δ 11.26 (s,
PPh3). Complex 8 was obtained in very small amounts and
was analytically impure (see Discussion).

276 Organometallics, Vol. 21, No. 2, 2002
Ta ble 1. Cr ysta l Da ta for Com p lexes 2a , 3a , 4a , 6a , 8, 9a ‚CH2Cl2, a n d 10‚1.5CH2Cl2
Vicente et al.
2a
3a
4a
6a
8
9a ‚CH2Cl2
10‚1.5CH2Cl2
formula
C24H24IN3Pd
C33H33IN4Pd
C34H33F3N4-
O3PdS
741.10
C35H32F3N5-
O3PdS
766.12
C58H66F6N4O6-
P2Pd2S2
1368.01
C50H50Cl2F3I- C46.5H43Cl3F6-
N6O3Pd2S N6O6PdS2
1282.62 1172.74
Mr
587.76
718.93
cryst size (mm)
0.62 × 0.42 × 0.60 × 0.25 × 0.60 × 0.25 × 0.64 × 0.24 × 0.25 × 0.09 ×
0.56 × 0.44 × 0.58 × 0.38 ×
0.38
0.15
0.20
0.18
0.09
0.40
0.34
cell constants
a (Å)
b (Å)
15.937(3)
8.255(1)
17.410(3)
90
100.28(1)
90
12.966(3)
12.378(3)
18.662(4)
90
90.28(3)
90
12.3735(6)
20.9499(13)
13.3414(7)
90
98.804(4)
90
8.127(1)
13.697(1)
15.975(1)
71.629(8)
81.22(1)
78.774(10)
1647.4(3)
2
43.682(8)
14.327(3)
20.743(4)
90
102.67(2)
90
14.3153(6)
23.4738(9)
15.8732(7)
90
105.903(3)
90
11.671(2)
14.029(2)
18.294(3)
100.938(14)
103.15(1)
111.112(10)
2596.4(7)
2
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
2253.7(6)
4
2995.2(12)
4
3417.7(3)
4
12665(4)
8
5129.8(4)
4
Z
λ (Å)
0.710 73
173(2)
Mo KR
graphite
P21/c
0.710 73
143(2)
Mo KR
graphite
P21/n
0.710 73
173(2)
Mo KR
graphite
P21/c
0.710 73
173(2)
0.710 73
143(2)
Mo KR
graphite
C2/c
0.710 73
173(2)
Mo KR
graphite
P21/c
0.710 73
173(2)
T (K)
radiation
monochromator
space group
Mo KR
graphite
P1h
Mo KR
graphite
P1h
µ (mm-1
max/min
transmissn (%)
)
2.208
0.487/0.341
1.678
0.862/0.720
0.659
0.879/0.693
0.688
0.751
1.506
0.666
0.8862/0.7998 0.862/0.356
0.5841/0.4860 0.805/0.699
abs cor
ψ scans
Siemens P4
ω
6 < 2θ < 50
(h; (k; +l
ψ scans
ψ scans
ψ scans
Siemens P4
ω
6 < 2θ < 50
-h; (k; (l
multiscan
Bruker SMART Siemens P4
ω and φ
ψ scans
ψ scans
Siemens P4
ω
6 < 2θ < 50
(h; +k; (l
diffractometer
scan method
2θ range (deg)
hkl range
no. of rflns
measd
Stoe STADI-4 Siemens P4
ω/θ
6 < 2θ < 50
+h, -k, (l
ω
ω
6 < 2θ < 50
(h; -k; (l
3.5 < 2θ < 53.7 6 < 2θ < 50
sphere
(h; +k; -l
6961
3950
0.035
0.0301
0.0764
5516
5280
0.0236
0.0323
0.0682
9803
5995
0.022
0.0321
0.0695
8397
5723
0.017
0.0369
0.1025
69 459
12 946
0.1586
0.0715
0.2003
10 733
8954
0.018
0.0259
0.0674
9284
8881
0.017
0.0493
0.1325
indep
Rint
R1a
wR2b
R1 ) ∑||Fo| - |Fc||/∑|Fo| for reflections with I > 2σ(I). wR2 ) [∑[w(Fo - Fc2)2]/∑[w(Fo2)2]]0.5 for all reflections; w-1 ) σ2(F2) + (aP)2
a
b
2
+ bP, where P ) (2Fc + Fo2)/3 and a and b are constants set by the program.
2
Syn th esis of [{P d [K2C,N-C(dNXy)C6H4NH2](CNXy)}2(µ-
I)]TfO (9a ). Tl(OTf) (42 mg, 0.12 mmol) was added to a
solution of 2a (140 mg, 0.24 mmol) in CH2Cl2 at 0 °C and the
resulting suspension warmed to room temperature overnight.
After this time the solution was filtered through MgSO4, the
solvent removed, and n-hexane added to give 9a as a bright
yellow solid. Yield: 100 mg, 70%. Dec pt: 94 °C. IR (Nujol,
cm-1): ν 3456 (NH), 3376 (NH), 2178 (CtN), 1640 (NC). 1H
The crystal of 8 was mounted as above on a Bruker SMART
1000 CCD diffractometer; data were recorded using ω and φ
scans.
Str u ctu r e Solu tion a n d Refin em en t. The structures
were solved by the heavy-atom method (2a , 3a , 4a , 6a , and
10‚1.5CH2Cl2) or by direct methods (8, 9a ) and refined aniso-
tropically on F2 (SHELXL-97 program).65 Hydrogen atoms
were included using a riding model or rigid methyl groups,
except as indicated below.
Sp ecia l F ea tu r es of Refin em en t. For compounds 2a , 3a ,
6a , and 9a , the amino group hydrogen atom(s) were located
in a difference Fourier synthesis and refined with restrained
N-H bond lengths. For compound 4a the methyl groups C(37)
and C(38) are disordered with two sites rotated by 60° from
one another (50% occupancy). For compound 6a the CF3 group,
which is disordered over two sites (65/35% occupancy), was
refined with a common carbon position and with isotropic
fluorine atoms. The maximum residual electron density of 1.44
e Å-3 is associated with the disordered CF3 group. In compound
8 one butyl group (at C17) and one triflate anion are disordered
over two positions. For 10‚1.5CH2Cl2 one of the CH2Cl2
molecules was refined with a common chlorine and carbon
position and with an isotropic chlorine atom disordered over
two sites (70/30% occupancy). The maximum residual electron
density of 1.38 e Å-3 is associated with the disordered CH2-
Cl2. The programs use neutral atom scattering factors, ∆f ′ and
∆f′′, and absorption coefficients from ref 66.
3
4
NMR (300 MHz, CDCl3): δ 8.08 (dd, J H,H ) 7 Hz, J H,H ) 1.5
3
4
Hz, 1 H, H6), 7.63 (dd, J H,H ) 7 Hz, J H,H ) 1.5 Hz, 1 H, H3),
3
3
4
7.45 (ddd, J H,H ) 7 Hz, J H,H ) 7 Hz, J H,H ) 1.5 Hz, 1 H, H4
3
3
4
or H5), 7.27 (ddd, J H,H ) 7 Hz, J H,H ) 7 Hz, J H,H ) 1.5 Hz,
3
1 H, H4 or H5), 7.10 (t, J H,H ) 8 Hz 1 H, para H Xy), 6.89 (d,
3J H,H ) 8 Hz 2 H, meta H’s Xy), 6.67 (d, J H,H ) 8 Hz 2 H,
3
3
meta H’s Xy), 6.23 (t, J H,H ) 8 Hz 1 H, para H Xy), 6.16 (s, 2
H, NH2), 2.15 (s, 6 H, 2Me), 2.03 (s, 6 H, 2Me). 13C{1H} NMR
(75 MHz, CDCl3): δ 150.92, 143.70, 142.50, 133.95, 132.33 (C-
H), 130.46, 129.11 (C-H), 128.91, 128.34, 127.75 (C-H),
127.51 (C-H), 127.45 (C-H), 126.87, 126.62 (C-H), 125.22
1
(C-H), 123.85 (C-H), 120.26 (q, J C,F ) 318 Hz, CF3), 19.15
(Me), 18.25 (Me). Anal. Calcd for C49H48F3IN6O3Pd2S: C, 49.14;
H, 4.04; N, 7.02; S, 2.68. Found: C, 49.28; H, 4.11; N, 6.71; S,
2.76. Single crystals of 9a were grown by slow diffusion of
n-hexane into solutions of 9a in CH2Cl2.
Cr yst a l St r u ct u r e Det er m in a t ion s. Da t a Collect ion .
Crystals were mounted in inert oil on a glass fiber and
transferred to the diffractometer (Siemens P4 with LT2 low-
temperature attachment) as summarized in Table 1. Unit cell
parameters were determined from a least-squares fit of ca. 60
accurately centered reflections (9° < 2θ < 25°). Data were
recorded using ω scans. Exceptions: the crystal of 3a was
mounted as above on a Stoe STADI-4 diffractometer; cell
constants were refined from (ω angles of 50 reflections in the
range 20° < 2θ < 23°; data were recorded using ω/θ-scans.
Resu lts a n d Discu ssion
We have previously reported the synthesis of the
complex [Pd{C6H4NH2-2}I(bpy)] (1a ; bpy ) 2,2′-bipyri-
(65) SHELXL 97; University of Go¨ttingen, Go¨ttingen, Germany.
(66) International Tables for Crystallography, Kluwer Academic:
Dordrecht, The Netherlands, 1992; Vol. C, Tables 6.1.1.4 (pp 500-
502), 4.2.6.8 (pp 219-222), and 4.2.4.2 (pp 193-199).

(2-Aminoaryl)palladium(II) Complexes
Organometallics, Vol. 21, No. 2, 2002 277
Sch em e 1
although with X ) Cl, the dinuclear complex [Pd{C(d
NtBu)CH2Ph}Cl(CNtBu)]2 was obtained.59 In our case,
the ability of the o-NH2 group to coordinate to the metal
atom to form a chelate is responsible for the formation
of the mononuclear complex 2a . However, the reaction
t
with BuNC seems to occur by a different mechanism.
It seems coordination of a third isonitrile ligand is faster
than the formation of the complex homologous to 2a .
However, this does not explain why 3a * was isolated
in lower yield when using stoichiometric amounts of the
reagents. We have observed this behavior previously
using 2-ROC6H4I (R ) H, C(O)Me) as the oxidative
addition reagent and proposed the following reaction
pathway.62 We assumed that the resulting [Pd(R)I(CNt-
Bu)2] (or that homologous to 2a ) (eq 1) quickly decom-
poses to 3a * and some polymeric complex (eq 2). When
a 1:3 molar ratio of Pd to tBuNC was used, not only does
the polymer not react with isonitrile to give 3a * but
other side reactions probably occur as well.
Similar reactions using 2-bromo-4-nitroaniline require
higher temperatures than those with 2-iodoaniline in
order to achieve the oxidative addition. Unfortunately,
this usually led to intractable mixtures. However, the
t
reaction of 1b or 1b′ with XyNC or BuNC (1:3 molar
ratio), respectively, gave the complex 3b or 3b*, respec-
tively. Similarly, the reaction of 2a or 1a with XyNC
(1:1 molar ratio) or BuNC (1:3 molar ratio), respectively,
dine), by reacting “Pd(dba)2” (dba ) dibenzylideneac-
etone) with 2-iodoaniline in the presence of bpy.16,17 By
a similar procedure, the complexes [Pd{C6H3NH2-2-
NO2-5}Br(L2)] (L2 ) bpy (1b), tmeda ) N,N,N′,N′-
tetramethylethylenediamine (1b′)) were obtained. Al-
though 1b could not be isolated as an analytically pure
compound, it could be used as the starting material for
the synthesis of several derivatives (Scheme 1).
t
gave the complex 3a or 3a *, respectively (Scheme 1). It
is noteworthy that in only one case, complex 2a , does
coordination of the NH2 group occur to give a cyclom-
etalated species. From the reaction of 1b or 1b′ with
t
both isonitriles or the reaction of 1a with BuNC in a
1:2 or even a 1:1 molar ratio, only the corresponding
complex 3 could be isolated. This also suggests that the
resulting complex 2 is unstable and decomposes to give
the corresponding complex 3. This contrasts with previ-
ously reported reactions of [PdClMe(L2)] (L2 ) bidentate
nitrogen donor ligand) with isonitriles in a 1:1 molar
ratio, affording the monoinserted complexes [PdCl{C(d
NR)Me}(L2)].21,29 In the case of the NO2-substituted aryl
derivatives, the presence of this electron-withdrawing
substituent could explain the decrease of the stability
of the corresponding complex 2 due to the reduced
coordinating ability of the amino group; this effect has
also been observed in the (2-amino-5-nitrophenyl)-
palladium and -platinum compounds studied previ-
ously.15,69 Moreover, the reaction of complexes 3 with
Tl(TfO) (TfO ) CF3SO3) led to decomposition products,
with the exception of 3a , which is transformed into the
cationic cyclopalladated complex cis-[Pd{κ2C,N-C(d
NXy)C6H4NH2-2}(CNXy)2]TfO (4a ) (Scheme 2) involving
one inserted and two coordinated XyNC molecules.
The reaction of “Pd(dba)2” with XyNC (Xy ) 2,6-
dimethylphenyl) and then addition of an excess of
2-iodoaniline (1:2:2 molar ratio) yielded the complex [Pd-
{κ2C,N-C(dNXy)C6H4NH2-2}I(CNXy)] (2a ) (Scheme 1).
t
When a similar reaction was carried out with BuNC
(1:2:3 molar ratio, Pd:tBuNC:2-iodoaniline), the complex
trans-[Pd{C(dNtBu)C6H4NH2-2}I(CNtBu)2] (3a *) was
obtained (Scheme 1). Therefore, the reaction involves
the coordination of three molecules of isonitrile per
palladium instead of the two molecules used. Surpris-
ingly, when a 1:3 stoichiometry was used, the yield was
lower. Complex 3a * could also be obtained by reacting
t
1a with BuNC in a 1:3 molar ratio.
t
The reaction between BuNC and Pd(0) complexes has
been shown to give “Pd(CNtBu)2” (eq 1).67
“Pd(CNtBu)2” + RX f [Pd(R)X(CNtBu)2] (1)
[Pd(R)X(CNtBu)2] f
2/ [Pd{C(dNtBu)R}X(CNR′) ]
1
t
+ /3“Pd(R)X” (2)
3
2
Complex 3a * or 3b* reacts with BuNC and Tl(TfO)
3a *
to give the cationic species 5a * or 5b*, respectively, with
one inserted and three coordinated isonitriles (Scheme
2). However, similar reactions of 3a or 3b with XyNC
give TlI and a complex mixture from which we could
not identify any product. Complex 3a * reacts with bpy
and Tl(TfO) (1:1.1:1.2) to give the cationic complex 6a *,
resulting from the substitution of one isonitrile and the
iodo ligands. A similar reaction starting from 3a , 3b,
or 3b* resulted in the formation of complex mixtures of
Reactions between acyl, aroyl, and alkyl chlorides and
“Pd(CNtBu)2” were reported to give the complexes [Pd-
(R)X(CNtBu)2] (eq 2, R ) MeC(O), PhC(O), (CH2)2CO2-
Et, CH(Ph)CO2Et, CH2CO2Me, X ) Cl) but not insertion
products.68 Similar complexes with R ) CH2Ph and X
) Br, I were isolated by reacting “Pd(CNtBu)2” with XR,
(67) Otsuka, S.; Nakamura, A.; Tatsuno, Y. J . Am. Chem. Soc. 1969,
91, 6994.
(68) Otsuka, S.; Nakamura, A.; Yoshida, T.; Naruto, M.; Ataka, K.
J . Am. Chem. Soc. 1973, 95, 3180.
(69) Vicente, J .; Abad, J . A.; Teruel, F.; Garc´ıa, J . J . Organomet.
Chem. 1988, 345, 233.

278 Organometallics, Vol. 21, No. 2, 2002
Vicente et al.
Sch em e 2
products. The homologous 6a was obtained by reacting
2a with bpy and Tl(TfO) (1:1:1) (Scheme 2). When CO
was bubbled for 30 min through the above mixture of
2a , bpy, and Tl(TfO) (0.68 mmol of each in acetone), a
complex mixture of products was obtained. After the
removal of TlI, a single crystal was isolated from the
solution, which an X-ray diffraction study showed to be
the cationic complex [Pd(R)(CNXy)(bpy)](TfO)2 (10),
where R is 2-(xylylamino)-3-xylylquinazolinium-4-yl (see
Scheme 2). Unfortunately, despite repeated attempts,
we have not been able to isolate 10 again or the other
products of the reaction. It is therefore difficult to
propose any explanation for its formation or to elucidate
the role played by the carbon monoxide.
between a phosphorus donor ligand and the aryl
ligand.17,70,71 Such a destabilizing effect can explain the
geometry of some palladium complexes,71 of some C-X
(X ) C, N, O, P) coupling processes,5,17,72 and also of an
oxygenation reaction that we have recently reported.16,17
The reaction of 3a * or 3b* with PPh3 in the presence
of Tl(TfO) gives rise to the formation of trans-[Pd{C(d
NR)C6H3NH2-2-Y-5}(CNtBu)2(PPh3)]TfO (Y ) H (7a *),
NO2 (7b*)). These complexes are unstable and decom-
pose slowly, preventing their complete purification.
When they were left in solution for 24 h at room
temperature, Et2O was slowly added, and the resulting
suspension left overnight in the refrigerator, a mixture
was obtained in which single crystals were separated
and studied by X-ray diffraction, proving to be the
cationic palladium(I) dimer [Pd2(CNtBu)4(PPh3)2](TfO)2
(8). From the above-mentioned mixture we attempted
unsuccessfully to isolate an analytically pure sample of
8. The mother liquors resulting from this treatment
contains a complex mixture of organic and/or organo-
1
metallic compounds, as revealed by the H NMR spec-
F igu r e 1. Thermal ellipsoid plot (50% probability level)
of 2a . Selected bond lengths (Å) and angles (deg): Pd-
C(20) ) 1.941(4), Pd-C(7) ) 2.027(4), Pd-N(1) ) 2.074-
(4), Pd-I ) 2.6981(5), N(2)-C(7) ) 1.268(5); C(20)-Pd-
C(7) ) 99.66(16), C(20)-Pd-I ) 87.23(12), N(1)-Pd-I )
90.27(10), C(7)-Pd-N(1) ) 82.88(15), C(7)-N(2)-C(11) )
126.0(3).
trum of the corresponding residue obtained by evapo-
ration of the solution to dryness; this may indicate a
nonselective radical decomposition process. The NMR
resonances in the spectra of 8 appear as impurities in
freshly prepared samples of 7a * or 7b*. The instability
of these complexes may be due to the transphobia

(2-Aminoaryl)palladium(II) Complexes
Organometallics, Vol. 21, No. 2, 2002 279
F igu r e 2. (A) Packing diagram of 2a , showing C(28)-H(28A)‚‚‚Pd#3 (#3: x, y + 1, z) and N(1)-H(1A)‚‚‚M (M ) centroid
of ring C(1)#2 to C(6)#2 (#2: -x, -y, -z)) hydrogen bonds. (B) Packing view along the b axis of 2a , showing two molecular
layers. Interactions have been omitted for clarity.
The formation of 8 shows a new manifestation of the
transphobic effect. Similar palladium(I) complexes [Pd2-
(CNR)4L2]n+ (n ) 2, R ) Me, L ) MeNC;73-76 n ) 2, R
) tBu, L ) tBuNC;76 n ) 0, R ) tBu, L ) I, Br,77 Cl;76-78
n ) 0, R ) Me, L ) I79) have been reported. One or two
isocyanides in [Pd2(CNR)6]2+ have preliminarily been
reported to be replaced in solution by PPh3 to give
[Pd2(CNMe)6-n(PPh3)n]2+ (n ) 1, 2).80
The reaction of 2a with Tl(TfO) in a 2:1 molar ratio
results in the formation of the binuclear complex [{Pd-
[κ2C,N-C(dNXy)C6H4NH2](CNXy)}2(µ-I)]TfO (9a), which,
as confirmed by its X-ray crystal structure, consists of
two cyclopalladated moieties connected by a bridging
iodine atom. It is surprising that complex 9a was still
obtained even when using a 1:1 molar ratio.
(70) Vicente, J .; Arcas, A.; Blasco, M. A.; Lozano, J .; Ram´ırez de
Arellano, M. C. Organometallics 1998, 17, 5374. Vicente, J .; Chicote,
M. T.; Rubio, C.; Ram´ırez de Arellano, M. C.; J ones, P. G. Organome-
tallics 1999, 18, 2750. J alil, M. A.; Fujinami, S.; Nishikawa, H. J .
Chem. Soc., Dalton Trans. 2001, 1091.
(71) Lohner, P.; Pfeffer, M.; Fischer, J . J . Organomet. Chem. 2000,
607, 12. Larraz, C.; Navarro, R.; Urriolabeitia, E. P. New J . Chem.
2000, 24, 623. Fernandez, S.; Navarro, R.; Urriolabeitia, E. P. J .
Organomet. Chem. 2000, 602, 151. Albert, J .; Cadena, J . M.; Granell,
J . R.; Solans, X.; Fontbardia, M. Tetrahedron: Asymmetry 2000, 11,
1943. Albert, J .; Cadena, J . M.; Delgado, S.; Granell, J . J . Organomet.
Chem. 2000, 603, 235. Albert, J .; Bosque, R.; Cadena, J . M.; Granell,
J . R.; Muller, G.; Ordinas, J . I. Tetrahedron: Asymmetry 2000, 11,
3335; Ferna´ndez-Rivas, C.; Ca´rdenas, D. J .; Mart´ın-Matute, B.; Monge,
A.; Gutie´rrez-Puebla, E.; Echavarren, A. M. Organometallics 2001, 20,
2998.
(72) Stille, J . K. Angew. Chem., Int. Ed. Engl. 1986, 25, 504.
Miyaura, N.; Suzuki, A. Chem. Rev. 1995, 95, 2457. Sadighi, J . P.;
Harris, M. C.; Buchwald, S. L. Tetrahedron Lett. 1998, 39, 5327.
Vicente, J .; Arcas, A.; Bautista, D.; Tiripicchio, A.; Tiripicchio-Camel-
lini, M. New J . Chem. 1996, 20, 345.
(73) Goldberg, S. Z.; Eisenberg, R. Inorg. Chem. 1976, 15, 535.
(74) Doonan, D. J .; Balch, A. L.; Goldberg, S. Z.; Eisenberg, R.;
Miller, J . S. J . Am. Chem. Soc. 1975, 97, 1961.
Str u ctu r e of Com p lexes. The NMR spectra of the
complexes are in agreement with the proposed struc-
1
tures. However, the H NMR spectrum of 4a shows a
broad signal corresponding to four Me groups that
transforms into two Me singlets at T < 10 °C. It is
reasonable to assume that the large trans influence of
the C-donor ligand favors the dissociation of the XyNC
ligand trans to the imidoacyl ligand, leading to an
intermolecular exchange of isonitriles. The crystal
structure of 4a confirms the weakening of this bond (see
below).
In the crystal structure of complex 2a (Figure 1), the
C(dNXy)C6H4NH2-2 ligand is bonded to the palladium
atom through both the imine carbon and the amino
nitrogen atoms. The cis disposition of the carbon donor
ligands is due to the large transphobia between C-donor
ligands.17,70 The structure is planar (mean deviation
0.034 Å), apart from both Xy rings, which are almost
perpendicular to the main plane (dihedral angles of 89.5
and 84.2°, respectively), thus avoiding steric hindrance.
(75) Boehm, J . R.; Doonan, D. J .; Balch, A. L. J . Am. Chem. Soc.
1976, 98, 8.
(76) Rettig, M. F.; Kirk, E. A.; Maitlis, P. M. J . Organomet. Chem.
1976, 111, 113.
(77) Otsuka, S.; Tatsuno, Y.; Ataka, K. J . Am. Chem. Soc. 1971, 93,
6705.
(78) Marsh, R. E. Acta Crystallogr., Sect. B 1997, 53, 317.
(79) Rutherford, N. M.; Olmstead, M. M.; Balch, A. L. Inorg. Chem.
1984, 23, 2833.
(80) Boehm, J . R.; Balch, A. L. J . Organomet. Chem. 1976, 112, C20.

280 Organometallics, Vol. 21, No. 2, 2002
Vicente et al.
F igu r e 3. Thermal ellipsoid plot (50% probability level)
of 3a . Selected bond lengths (Å) and angles (deg): I-Pd )
2.7246(9), Pd-C(3) ) 1.969(4), Pd-C(4) ) 1.985(4), Pd-
C(2) ) 2.059(4), N(2)-C(2) ) 1.264(5), N(3)-C(3) ) 1.141-
(5), N(4)-C(4) ) 1.140(5); C(3)-Pd-C(2) ) 88.01(14),
C(4)-Pd-C(2) ) 90.07(14), C(3)-Pd-I ) 93.31(11) C(4)-
Pd-I ) 87.99(11), C(2)-N(2)-C(21) ) 126.5(3), C(3)-
N(3)-C(31) ) 175.0(4), C(4)-N(4)-C(41) ) 169.1(4), N(2)-
C(2)-C(11) ) 121.2(3), N(2)-C(2)-Pd ) 125.5(3), C(11)-
C(2)-Pd ) 113.2(3), N(3)-C(3)-Pd ) 176.9(3), N(4)-C(4)-
Pd ) 171.9(3).
3
A Csp -H‚‚‚Pd (C(28)-H(28A)‚‚‚Pd#3) intermolecular
interaction is observed (Figure 2A). The C-H bond
approaches the Pd atom from one of the axial positions,
which could be interpreted as a hydrogen bond, as
occurs in other square-planar complexes of group 10
elements;81-83 this interaction links molecules to form
infinite linear chains parallel to the b axis. Pairs of these
chains are self-assembled through mutual intermolecu-
lar N-H hydrogen bonds with the π system of the arene
C(1)#2-C(6)#2 giving a double chain (Figure 2A). The
distance of the H atom to the aromatic centroid (M)
(H(1A)‚‚‚M ) 2.444 Å) is much shorter than the dis-
tances to any of the individual C atoms (distance range
2.61-3.08 Å). Additionally, the angle between the
H(1A)‚‚‚M vector and the normal to the phenyl ring is
11°, showing that the interaction is close to centered.84
The remaining hydrogen atom of the amino group
interacts with an iodine atom of another different
molecule (N(1)-H(2A)‚‚‚I#1). This interaction is readily
identified as an N-H‚‚‚I-Pd hydrogen bond82,83 and
leads to zigzag chains, also parallel to the b axis,
connecting the double linear chains described above. As
a consequence of the three different hydrogen bond
types found in the crystal, a superstructure of molecular
layers parallel to the bc plane is observed (Figure 2B).
Complex 3a (Figure 3) exhibits a slightly distorted
square-planar geometry; the iodine atom lies 0.36 Å out
of the plane of Pd, C2, C3, and C4 (mean deviation 0.02
Å). Two hydrogen bonds involve the amine group as
donor: the intramolecular N1-H01‚‚‚N2 (H‚‚‚N ) 2.05-
(3) Å, N-H‚‚‚N ) 136(4)°) and the intermolecular N1-
F igu r e 4. (A) Thermal ellipsoid plot (50% probability level)
of the cation of 4a and (B) N(1)-H(1A)‚‚‚O(3) and N(1)-
H(1B)‚‚‚O(2)#1 (#1: x, -y + 1/2, z + 1/2) intermolecular
interactions forming zigzag chains. Selected bond lengths
(Å) and angles (deg): Pd-C(8) ) 1.950(3), Pd-C(7) )
2.034(3), Pd-N(1) ) 2.068(2), Pd-C(9) ) 2.087(3), N(2)-
C(7) ) 1.262(3), N(2)-C(11) ) 1.399(3), N(3)-C(8) ) 1.149-
(3), 1.409(3), N(4)-C(9) ) 1.144(3); C(8)-Pd-C(7) ) 95.28-
(11), C(7)-Pd-N(1) ) 82.97(10), C(8)-Pd-C(9) ) 92.58(11),
N(1)-Pd-C(9) ) 90.11(10), C(7)-N(2)-C(11) ) 125.6(2),
C(8)-N(3)-C(21) ) 177.1(3), C(9)-N(4)-C(31) ) 177.9-
(3).
H02‚‚‚I (H‚‚‚I ) 3.04(3) Å, N-H‚‚‚I ) 169(5)°), linking
molecules related by the n glide.
The crystal structure for compound 4a (Figure 4A)
shows the palladium center in a distorted square-planar
environment with an angle of 10.8° between the N(1)-
Pd-C(7) and C(8)-Pd-C(9) planes. The much greater
trans influence exerted by the iminoacyl carbon donor
ligand with respect to that of the coordinated NH2 group
is shown by the significantly longer Pd-C(9) bond
distance (2.089(3) Å) compared to Pd-C(8) (1.948(3) Å).
As mentioned above, the weakening of the Pd-C(9)
bond could be the origin of the behavior shown by this
complex in solution. Each hydrogen of the amino group
acts as a hydrogen bond donor to an oxygen atom of two
different triflate anions forming zigzag chains parallel
to the c axis (N(1)‚‚‚O(3) ) 2.937(3) Å, H(1A)‚‚‚O(3) 2.0
Å, N(1)-H(1A)‚‚‚O(3) ) 157.4° and N(1)‚‚‚O(2)#1
(81) Calhorda, M. J . Chem. Commun. 2000, 801. Braga, D.; Grepioni,
F.; Desiraju, G. R. Chem. Rev. 1998, 98, 1375. Aleya, E. O.; Ferguson,
G.; Kannan, S. Chem. Commun. 1998, 345.
(82) Brammer, L.; Charnock, J . M.; Goggin, P. L.; Goodfellow, R.
J .; Koetzle, T. F.; Orpen, A. G. J . Chem. Soc., Chem. Commun. 1987,
443.
(83) Brammer, L.; Charnock, J . M.; Goggin, P. L.; Goodfellow, R.
J .; Orpen, A. G.; Koetzle, T. F. J . Chem. Soc., Dalton Trans. 1991,
1789.
(84) Steiner, T.; Mason, S. A. Acta Crystallogr., Sect. B 2000, 56,
254.

(2-Aminoaryl)palladium(II) Complexes
Organometallics, Vol. 21, No. 2, 2002 281
F igu r e 5. Thermal ellipsoid plot (50% probability level)
of 6a showing N(2)-H(2A)‚‚‚N(1) and N(2)-H(2B)‚‚‚O(2)
hydrogen bonds. All other hydrogen atoms have been
omitted for clarity. Selected bond lengths (Å) and angles
(deg): Pd-C(20) ) 1.939(3), Pd-C(10) ) 2.015(3), Pd-N(4)
) 2.100(3), Pd-N(3) ) 2.137(3), N(1)-C(10) ) 1.279(5),
N(5)-C(20) ) 1.146(5); C(20)-Pd-C(10) ) 87.32(13),
C(10)-Pd-N(4) ) 94.44(12), C(20)-Pd-N(3) ) 100.19(12),
N(4)-Pd-N(3) ) 78.05(11), C(10)-N(1)-C(11) ) 121.9(3),
C(20)-N(5)-C(21) ) 178.1(4).
F igu r e 7. (A) Thermal ellipsoid plot (50% probability level)
of 9a showing N(1)-H(1B)‚‚‚O(2), N(3)-H(3A)‚‚‚O(2), C(6)-
H(6)‚‚‚O(1), and C(26)-H(26)‚‚‚O(3) hydrogen bonds. (B)
Dimers of 9a formed through N(1)-H(1)‚‚‚I# (#: -x + 1,
-y + 1, +z + 1) hydrogen bonds. Selected bond lengths
(Å) and angles (deg): I-Pd(2) ) 2.7604(3), I-Pd(1) )
2.7680(3), Pd(1)-C(8) ) 1.955(3), Pd(1)-C(7) ) 2.025(3),
Pd(1)-N(1) ) 2.095(2), Pd(2)-C(10) ) 1.953(3), Pd(2)-C(9)
) 2.031(3), Pd(2)-N(3) ) 2.088(2), N(2)-C(7) ) 1.257(4),
N(4)-C(9) ) 1.252(4), N(5)-C(10) ) 1.154(4), N(6)-C(8)
) 1.151(4); Pd(2)-I-Pd(1) ) 117.700(10), C(8)-Pd(1)-C(7)
) 96.03(12), C(7)-Pd(1)-N(1) ) 82.48(11), C(8)-Pd(1)-I
) 91.21(9), N(1)-Pd(1)-I ) 90.88(7), C(10)-Pd(2)-C(9) )
96.46(12), C(9)-Pd(2)-N(3) ) 82.66(11), C(10)-Pd(2)-I )
89.79(9), N(3)-Pd(2)-I ) 91.27(7).
F igu r e 6. Thermal ellipsoid plot (30% probability level)
of the cation of 8. Pd(1)-C(1) ) 1.980(7), Pd(1)-C(6) )
1.979(7), Pd(1)-P(1) ) 2.3560(14), Pd(1)-Pd(2) ) 2.5596-
(7), Pd(2)-C(11) ) 1.964(5), Pd(2)-C(16) ) 1.983(6), Pd-
(2)-P(2) ) 2.3629(14), C(1)-N(1) ) 1.126(8), C(6)-N(2) )
1.151(8), C(11)-N(3) ) 1.158(7), C(16)-N(4) ) 1.140(7);
C(1)-Pd(1)-C(6) ) 165.7(2), C(1)-Pd(1)-P(1) ) 95.55(15),
C(6)-Pd(1)-P(1) ) 98.09(15), C(11)-Pd(2)-C(16) ) 162.9-
(2), C(11)-Pd(2)-P(2) ) 96.80(15), C(16)-Pd(2)-P(2) )
99.69(16).
membered ring (N(1) 0.55 Å out of the C(10)-C(1)-
C(2)-N(2)-H(2A) plane). The remaining hydrogen atom
of the amino group is involved in a hydrogen bond to
the triflate anion (N(2)‚‚‚O(2) ) 3.100(5) Å, H(2B)‚‚‚O(2)
) 2.35(4) Å, N(2)-H(2B)‚‚‚O(2) ) 148(5)°) (Figure 5).
The cation of the Pd(I) complex 8 (Figure 6) consists
of two Pd atoms, each having a distorted-square-planar
geometry. The main distortion is the narrowing of the
C-Pd-C angles (162.9(2), 165.7(2)°) in a direction away
from the phosphine ligands (P-Pd-C range 95.55(15)-
99.69(16)°). In similar complexes with less hindered
“axial” ligands, such distortion is less pronounced.73,79
The Pd-Pd (2.5596(7) Å) and Pd-C bond lengths
(1.964(5)-1.983(6) Å) are in the ranges found in struc-
tures of related complexes solved with similar ac-
curacy.73,79,85,86 The angle between the two coordination
planes (86.0°) is in the upper limit of the reported
data.73,79,85
(#1: x, -y + 1/2, z + 1/2) ) 2.937(3) Å, N(1)-
H(1B)‚‚‚O(2)#1 ) 2.07 Å, N(1)-H(1B)‚‚‚O(2)#1 ) 157.4°)
(Figure 4B).
Complex 6a (Figure 5) shows the palladium atom in
a square-planar environment. The plane formed by the
Pd coordination plane and the bpy ligand (mean devia-
tion 0.039 Å) is almost perpendicular to the aryl amino
group (dihedral angle 87.8°). The distance for the Pd-
N(3) bond (2.137(3) Å) is longer than for the Pd-N(4)
bond (2.100(3) Å). This indicates a greater trans influ-
ence of the iminoacyl ligand with respect to the isonitrile
ligand. An intramolecular hydrogen bond N-H‚‚‚N
(N(2)‚‚‚N(1) ) 2.828(5) Å, H(2A)‚‚‚N(1) ) 2.24(5) Å,
N(2)-H(2A)‚‚‚N(1) ) 126(4)°) forms a half-chair six-

282 Organometallics, Vol. 21, No. 2, 2002
Vicente et al.
the triflate anion. In addition, there are two weak
hydrogen bonds to the remaining oxygen atoms of the
triflate anion, C(6)-H(6)‚‚‚O(1) and C(26)-H(26)‚‚‚O(3)
(Figure 7A) (see the Supporting Information). These
supportive
hydrogen
bonds,
forming
two
‚‚‚O-S-O‚‚‚H-N-C-C-H‚‚‚ eight-membered rings,
could produce the strong distortion found for both
chelate rings. In the crystal, dimers are formed through
intermolecular N-H‚‚‚I hydrogen bonds, forming the
eight-membered ring I-Pd(1)-N(1)-H(1)‚‚‚I#-Pd(1)#-
N(1)#-H(1)# (#: -x + 1, -y + 1, +z + 1) (Figure 7B).
A weak C-H‚‚‚O interaction involving the dichlo-
romethane molecule is also observed (C(62)-
H(62B)‚‚‚O(1)).
The molecular structure of 10‚1.5CH2Cl2 (Figure 8)
shows a distorted-square-planar palladium environment
with a dihedral angle of 11.6° for the planes C(9)-Pd-
C(7) and N(8)-Pd-N(6). The bpy ligand is not planar,
and the dihedral angle between both rings is 9.2°. The
N-C bond distances in the heterocyclic part of the
quinazoline ring and the N(3)-C(8) bond length are in
a range of 1.321(5)-1.408(5) Å, suggesting a strong
electronic delocalization involving these atoms, as in-
dicated in Scheme 2. In fact, the C(11)-N(2)-C(8)-
N(3)-C(21) fragment is coplanar with the quinazoline
ring (mean deviation 0.038 Å). The amino group N(3)-
H(3N) makes a strong hydrogen bond with one O atom
F igu r e 8. Thermal ellipsoid plot (50% probability level)
of the cation of 10. Hydrogen atoms have been omitted for
clarity. Selected bond lengths (Å) and angles (deg): Pd-
C(9) ) 1.944(4), Pd-C(7) ) 2.009(4), Pd-N(6) ) 2.050(4),
Pd-N(5) ) 2.078(3), N(1)-C(8) ) 1.321(5), N(1)-C(2) )
1.361(5), N(2)-C(7) ) 1.356(5), N(2)-C(8) ) 1.408(5),
N(2)-C(11) ) 1.461(5), N(3)-C(8) ) 1.335(5), N(4)-C(9)
) 1.145(5); C(9)-Pd-C(7) ) 85.82(16), C(7)-Pd-N(6) )
96.79(15), C(9)-Pd-N(5) ) 98.23(15), N(6)-Pd-N(5) )
80.11(14), C(8)-N(1)-C(2) ) 118.0(3), C(7)-N(2)-C(8) )
121.6(3), C(7)-N(2)-C(11) ) 117.9(3), C(8)-N(2)-C(11) )
120.3(3), C(8)-N(3)-C(21) ) 122.2(3), C(9)-N(4)-C(31) )
174.1(4).
The structure of the cation of 9a ‚CH2Cl2 (Figure 7A)
shows an iodine atom bridging two palladium centers,
with every palladium atom bonded to both a terminal
isonitrile and a chelating C(dNXy)C6H4NH2-2 ligand.
For both Pd(1) and Pd(2) the C(dNXy)C6H4NH2-2 ligand
is bonded to the imine carbon trans to iodine and the
amino nitrogen atom trans to the isonitrile carbon atom.
Such geometry is in accord with the large transphobia
between C-donor ligands. The iodine bridge is not
symmetric (Pd(1)-I ) 2.7680(3) Å and Pd(2)-I )
2.7604(3) Å) and shows an angle Pd(1)-I-Pd(2) of
117.70(1)°. In contrast to compounds 2a and 4a , the
chelate rings are not planar; angles of 19.5° for the
N(1)-C(1)-C(2)-C(7) and N(1)-Pd(1)-C(7) planes and
14.4° for the N(3)-C(21)-C(22)-C(9) and N(3)-Pd(2)-
C(9) planes are observed. Both amino groups N(1) and
N(3) form a strong hydrogen bond to the O(2) atom of
of
a
triflate anion (N(3)‚‚‚O(4)
)
2.907(5) Å,
H(3N)‚‚‚O(4) ) 2.03(2) Å, N(3)-H(3N)‚‚‚O(4) ) 163(4)°)
and weak C-H‚‚‚O interactions involving aromatic
rings, a solvent molecule and both triflate anions are
also observed (see the Supporting Information).
Ack n ow led gm en t. We thank the Direccio´n General
de Investigacio´n Cient´ıfica y Te´cnica (PB97-1047), IN-
TAS (97-166), and the Fonds der Chemischen Industrie
for financial support. A.D.F. and J .L.-S. are grateful to
the DGESIC (Spain) and Fundacion Seneca (Comunidad
Autonoma de la Region de Murcia, Spain), respectively,
for grants.
Su p p or tin g In for m a tion Ava ila ble: Listings of all re-
fined and calculated atomic coordinates, all anisotropic ther-
mal parameters, and all bond lengths and angles for com-
pounds 2a , 3a , 4a , 6a , 8, 9a ‚CH2Cl2, and 10‚1.5CH2Cl2.
Crystallographic files for these compounds are also available
in CIF format. This material is available free of charge via
the Internet at http://pubs.acs.org.
(85) Tanase, T.; Ukaji, H.; Yamamoto, Y. J . Chem. Soc., Dalton
Trans. 1996, 3059.
(86) Tanase, T.; Kawahara, K.; Ukaji, H.; Kobayashi, K.; Yamazaki,
H.; Yamamoto, Y. Inorg. Chem. 1993, 32, 3682.
OM0104971