Syntheses and Structures of the Complexes cis-[M(C6F5)2(N-X)] (M = Pd, Pt; N-X = 2-Iodoaniline, 2-Benzoylpyridine) Containing N-X Acting as a Didentate Chelating Ligand and Displaying I→M or O→M Interactions

Article abstract of DOI:10.1021/ic950283+

Complexes cis-[M(C₆F₅)₂(THF)₂] (M = Pd, Pt) are weak Lewis acids and react with the halocarbon ligand 2-iodoaniline (R-I) yielding the corresponding cis-[M(C₆F₅)₂(R-I)] [M = Pd (

Full text of DOI:10.1021/ic950283+

56
Inorg. Chem. 1996, 35, 56-62
Syntheses and Structures of the Complexes cis-[M(C6F5)2(NkX)] (M = Pd, Pt; NkX =
2-Iodoaniline, 2-Benzoylpyridine) Containing NkX Acting as a Didentate Chelating Ligand
and Displaying IfM or OfM Interactions
Jose´ Mar´ıa Casas, Larry R. Falvello, Juan Fornie´s,* and Antonio Mart´ın
Departamento de Qu´ımica Inorga´nica, Instituto de Ciencia de Materiales de Arago´n,
Universidad de Zaragoza-C.S.I.C. 50009 Zaragoza, Spain
ReceiVed March 9, 1995X
Complexes cis-[M(C6F5)2(THF)2] (M ) Pd, Pt) are weak Lewis acids and react with the halocarbon ligand
2-iodoaniline (R-I) yielding the corresponding cis-[M(C6F5)2(R-I)] [M ) Pd (1), Pt (2)]. In these complexes
a (C-)I-M bond is present. The use of other 2-haloanilines (halogen ) F, Cl, Br) does not yield the analogous
complexes because of the lesser nucleophilic character of the halogen involved. The presence of the (C-)I-Pt
bond in 2 has been confirmed by an X-ray structure determination, which also reveals an N-H‚‚‚M hydrogen
bond between two neutral molecules. Complex 2 crystallizes in the space group P1h: Z ) 4; a ) 11.797(4) Å;
b ) 13.735(4) Å; c ) 14.107(4) Å; R ) 97.24(2)°; â ) 90.91(2)°; γ ) 99.44(2)°; V ) 2235(2) Å3. Similarly,
complexes cis-[M(C6X5)2(THF)2] (M ) Pd, Pt; X ) F, Cl) react with the ligand 2-benzoylpyridine {R-C(O)-
Ph}, in which the oxygen atom of the ketonic group can behave as a nucleophilic center, yielding the complexes
cis-[M(C6X5)2{R-C(O)Ph}] [M ) Pd, X ) F (3); M ) Pt, X ) F (4), Cl (5)]. Complex 3 crystallizes in the
space group C2/c: Z ) 16; a ) 26.284(3) Å; b ) 10.623(1) Å; c ) 31.423(4) Å; â ) 93.15(1)°; V ) 8760(2)
Å3. The I-M or O-M bonds in complexes 1-5 are weak and can be easily broken by the addition of neutral
(CO, PPh3, and CH3CN) or anionic (Br-) ligands.
Introduction
forming RX-M complexes is relatively rare and recent.4 Thus,
only one palladium4b and two platinum complexes5 have been
reported prior to this work.
Some years ago we described the syntheses of complexes of
stoichiometry cis-[M(C6X5)2(THF)2] (M ) Pd, Pt; X ) F, Cl;
THF ) tetrahydrofuran).1 The study of their reactivity has
shown that they are excellent precursors for the preparation of
complexes not accessible by other routes since the two THF
groups are easily replaced by other ligands.2 In the “cis-
M(C6X5)2” fragment the metal atom has acid properties and is
able to accept electron density from a ligand with a suitable
nucleophilic center, forming a XfM dative bond. A judicious
choice of the nucleophilic ligand can lead to the preparation of
complexes containing interesting structural features. In this
work we report the syntheses and structural characterization of
complexes of the type cis-[M(C6X5)2(NkX)], in which NkX is
a bidentate N-donor ligand containing a substituent nucleophilic
center such as halogen (halocarbon ligands) or oxygen atoms.
Halocarbons have the general formula RX in which R is an
organic group and X is a halogen atom. This kind of compound
is one of the more important and better represented organic
substances.3 However, the use of halocarbons as ligands
There are several reasons that explain the relatively small
number of halocarbon complexes known. One is that the
halocarbons are very weak bases so that the RX-M bonds
formed are easily displaced by other donor ligands. In sharp
contrast, complexes of the halide ions X-, especially where X
) Cl, Br, or I, constitute one of the largest classes of
coordination compounds mainly because the anions X- are
much more basic than the halocarbons RX. Thus, among the
halocarbons, iodocarbons should be the best candidates as
ligands, being the best donors, especially toward soft Lewis acids
such as the “cis-M(C6X5)2” fragment.
Other common decomposition pathways for halocarbon
complexes are nucleophilic attack at the R-carbon3 and oxidative
addition to the metal center to give an alkyl metal halide,
R-M-X. Haloarenes have a greater C-X bond strength that
helps to prevent this reaction. The chelate effect can be used
to increase the binding tendency of ligands, and thus, chelating
haloarenes are the largest class of halocarbon ligand found to
date.
X Abstract published in AdVance ACS Abstracts, November 15, 1995.
(1) Uso´n, R.; Fornie´s, J.; Toma´s, M.; Menjo´n, B. Organometallics 1985,
4, 1912.
The oxygen atoms of ketonic groups are also nucleophiles
able to donate electron density to the metal center in the “cis-
M(C6X5)2” fragment in a way similar to that of halogen atoms
in halocarbon ligands. This capability has been used in the
preparation of complexes possesing ROfM bonds.
(2) (a) Uso´n, R.; Fornie´s, J.; Toma´s, M.; Menjo´n, B.; Carnicer, J.; Welch,
A. J. J. Chem. Soc., Dalton Trans. 1990, 150. (b) Uso´n, R.; Fornie´s,
J.; Toma´s, M.; Menjo´n, B. Organometallics 1986, 5, 1581. (c) Uso´n,
R.; Fornie´s, J.; Toma´s, M.; Navarro, R.; Casas, J. M. J. Chem. Soc.,
Dalton Trans. 1989, 169. (d) Falvello, L. R.; Fornie´s, J.; Navarro, R.;
Sicilia, V.; Toma´s, M. Angew. Chem., Int. Ed. Eng. 1990, 29, 891.
(e) Fornie´s, J.; Menjo´n, B.; Go´mez, N.; Toma´s, M. Organometallics
1992, 11, 1187. (f) Fornie´s, J.; Go´mez, M. A.; Lalinde, E.; Moreno,
M. Organometallics 1992, 11, 2873. (g) Uso´n, R.; Fornie´s, J.; Toma´s,
M.; Menjo´n, B.; Fortun˜o, C.; Welch, A. J.; Smith, E. J. Chem. Soc.,
Dalton Trans. 1993, 275. (h) Berenguer, J. R.; Falvello, L. R; Fornie´s,
J.; Lalinde, E.; Toma´s, M. Organometallics 1993, 12, 6. (i) Casas, J.
M.; Fornie´s, J.; Mart´ın, A.; Menjo´n, B. Organometallics 1993, 12,
4376.
(3) Patai, S., Ed. The Chemistry of the Carbon-Halogen Bond; Wiley:
New York, 1973.
(4) (a) Kulawiec, R. J.; Crabtree, R. H. Coord. Chem. ReV. 1990, 99, 89,
and references given therein. (b) Peng, T.-S.; Winter, C. H.; Gladysz,
J. A. Inorg. Chem. 1994, 33, 2534. (c) Harrison, R.; Arif, A. M.;
Wulfsberg, G. ; Russell, L.; Ju, T.; Kiss, G.; Hoff, C. D.; Richmond,
T. G. J. Chem. Soc., Chem. Commun. 1992, 1374.
(5) Gomes-Carneiro, T. M.; Jackson, R. D.; Downing, J. H.; Orpen, A.
G.; Pringle, P. G. J. Chem. Soc., Chem. Commun. 1991, 317.
0020-1669/96/1335-0056$12.00/0 © 1996 American Chemical Society

cis-[M(C6F5)2(NkX)]
Inorganic Chemistry, Vol. 35, No. 1, 1996 57
hydrogen region. 19F NMR (CDCl3, room temperature), ppm: o-F,
Experimental Section
3
3
-120.42 (2F, JPt-F ) 516.7 Hz) and -121.76 (2F, JPt-F ) 428.5
Hz); m-F, -163.89 (2F) and -164.93 (2F); p-F, -161.02 (1F) and
-161.62 (1F).
Anal. Found (Calcd) for 5: N, 1.61 (1.60); C, 32.51 (32.87); H,
1.06 (1.03). IR, cm-1: C6Cl5, 1335(s), 1319(s), 1294(s), 676(s), and
625(s); R-C(O)Ph, 598(m), 1584(m), 1575(m), 1551(s), 1268(m),
1026(m), 960(m), 814(m), 769(m), 751(s), 697(s), and 651(m). 1H
NMR (CDCl3, room temperature), ppm: The signals appear overlapped
in the zone of the aromatic hydrogens.
cis-[Pt(C6F5)2(R-I)(CO)] (6). Through a solution of 0.200 g (0.267
mmol) of cis-[Pt(C6F5)2(R-I)], 2, in CH2Cl2 (20 mL) at room
temperature was bubbled CO for 5 min. After evaporation to dryness
and addition of n-hexane (20 mL) a white solid, cis-[Pt(C6F5)2(R-I)-
(CO)] (6), was isolated in 80% yield. cis-[Pd(C6F5)2(R-I)], 1, does
not react with CO under similar conditions.
C, H, and N analyses were done with a Perkin-Elmer 240B
microanalyzer. The IR spectra were recorded on a Perkin-Elmer 883
or 1710 FTIR spectrophotometer (4000-200 cm-1) using Nujol mulls
between polyethylene sheets or CH2Cl2 solutions in NaCl windows.
The 1H and 19F NMR spectra were recorded on a Varian XL-200 or a
Unity-300 in CD2Cl2, CDCl3, or HDA (acetone-d6) solutions. cis-
[M(C6X5)2(THF)2] (M ) Pd, Pt; X ) F, Cl) was prepared as described
elsewhere.1 2-Fluoroaniline, 2-chloroaniline, 2-bromoaniline, 2-iodoa-
niline, and 2-benzoylpyridine were obtained from commercial sources
and used as delivered.
cis-[M(C6F5)2(R-I)] [R-I ) 2-Iodoaniline; M ) Pd (1), Pt (2)].
To a solution of 0.200 g of cis-[M(C6F5)2(THF)2] (M ) Pd, 0.342 mmol;
M ) Pt, 0.297 mmol) in 20 mL of CH2Cl2 was added 2-iodoaniline in
a 1:1 molar ratio (M ) Pd, 0.074 g, 0.34 mmol; M ) Pt, 0.065 g, 0.30
mmol). The resulting brown solution was stirred at room temperature
for 15 min, and the solvent was evaporated to dryness. The residue
was thrice treated with 3 mL of CHCl3 and then evaporated to dryness,
Anal. Found (Calcd) for 6: N, 2.16 (1.80); C, 30.34 (29.39); H,
0.73 (0.78). IR, cm-1: C6F5 X-sensitive,6 817(s) and 798(s); others,
1639(m), 1506(vs), 1064(s), and 964(vs); R-I, 3331(m), 3263(m),
1590(m), 1575(m), 1126(s), and 757(s); ν(CO) ) 2123(vs). 1H NMR
(CD2Cl2, room temperature), ppm: 5.47 (s, 2H, 2JPt-H ) 35 Hz); 6.99
(t, 1H); 7.30 (d, 1H); 7.44 (t, 1H); 7.93 (d, 1H). 19F NMR (CD2Cl2,
i
and finally, the residue was treated with PrOH, rendering complexes
1 (96% yield) and 2 (90% yield).
Anal. Found (Calcd) for 1: N, 2.29 (2.12); C, 33.95 (32.78); H,
1.25 (0.92). IR, cm-1: C6F5 X-sensitive,6 797(s) and 783(s); others,
1638(m), 1600(m), 1501(vs), 1057(vs), and 960(vs); R-I, 3332(s),
3277(m), 1582(m), 1556(m), 1356(m), 1080(s), 814(m), 761(s), 647(m),
and 429(m); in solution, ν(N-H) ) 3307(m) and 3253(m). 1H NMR
(CDCl3, room temperature), ppm: 4.64 (s, 2H); 7.19 (m, 1H); 7.28 (d,
1H); 7.44 (t, 1H); 7.77 (d, 1H). 19F NMR (CDCl3, room temperature),
ppm: o-F, -117.04 (2F) and -119.09 (2F); m-F, -164.27 (2F) and
-165.55 (2F); p-F, -160.76 (1F) and -161.93 (1F).
3
room temperature), ppm: o-F, -118.22 (2F, JPt-F ) 413.4 Hz) and
3
-118.77 (2F, JPt-F ) 359.6 Hz); m-F, -161.77 (2F) and -163.13
(2F); p-F, -156.93 (1F) and -159.28 (1F).
Reaction of 1 and 2 with CH3CN. To a solution of cis-[M(C6F5)2-
(R-I)] [M ) Pd (1) or Pt (2)] in 20 mL of CH2Cl2, 5 mL of CH3CN
was added. The solution was stirred at room temperature for 5 min,
and the solvent was evaporated to dryness. The residue was treated
with n-hexane, rendering cis-[M(C6F5)2(CH3CN)2].
Reaction of 2 with NBu4Br. To a solution of 0.120 g (0.16 mmol)
of cis-[Pt(C6F5)2(R-I)] (2) in 20 mL of CH2Cl2 was added 0.052 g
(0.16 mmol) of NBu4Br. The solution was stirred at room temperature
for 15 min, and the solvent was evaporated to dryness. The residue
was treated with n-hexane, rendering [NBu4]2[Pt2(µ-Br)2(C6F5)4].
cis-[Pt(C6F5)2{R-C(O)Ph}(CO)] (7). CO was bubbled for 5 min
through a solution of 0.200 g (0.281 mmol) of cis-[Pt(C6F5)2{R-
C(O)Ph}] (4) in CH2Cl2 (20 mL) at room temperature. The red solution
became colorless. After evaporation to dryness and addition of
n-hexane (20 mL) a white solid cis-[Pt(C6F5)2{R-C(O)Ph}(CO)] (7)
was isolated in 87% yield. cis-[Pd(C6F5)2{R-C(O)Ph}] (3) does not
react with CO under similar conditions.
Anal. Found (Calcd) for 2: N, 1.68 (1.87); C, 29.66 (28.89); H,
0.86 (0.81). IR, cm-1: C6F5 X-sensitive,6 810(s) and 801(s); others,
1638(m), 1609(m), 1506(vs), 1064(vs), and 960(vs); R-I, 3315(m),
1557(m), and 757(s); in solution ν(N-H) ) 3289(m) and 3240(m).
1H NMR (CDCl3, room temperature), ppm: 5.38 (s, 2H, JPt-H ) 37
2
Hz); 7.24 (d, 1H); 7.38 (t, 1H); 7.41 (t, 1H); 7.73 (d, 1H). 19F NMR
3
(CDCl3, room temperature), ppm: o-F, -117.00 (2F, JPt-F ) 435.4
3
Hz) and -121.55 (2F, JPt-F ) 491.9 Hz); m-F, -163.03 (2F) and
-164.57 (2F); p-F, -159.72 (1F) and -161.52 (1F).
Attempts To Prepare Similar Compounds with R-X (R-X )
2-Fluoroaniline, 2-Chloroaniline, or 2-Bromoaniline). The reactions
between cis-[M(C6F5)2(THF)2] and R-X (R-X ) 2-fluoroaniline,
2-chloroaniline, or 2-bromoaniline) under similar conditions only
renders a mixture of unidentified compounds.
Anal. Found (Calcd) for 7: N, 1.81 (1.89); C, 40.84 (40.55); H,
1.04 (1.23). IR, cm-1: C6F5 X-sensitive,6 808(s) and 798(s); others,
1638(m), 1506(vs), 1064(vs), and 961(vs); R-C(O)Ph, 1681(s),
1600(m), 1573(m), 1558(m), 1321(m), 1304(f), 1278(m), 1184(m),
1175(m), 1160(m), 1108(m), 1026(m), 944(s), 931(m), 775(m), 759(m),
701(s), 649(s), 514(m), 460(m), and 368(m); ν(CO) ) 2128(vs). 1H
cis-[M(C6X5)2{R-C(O)Ph}] [R-C(O)Ph ) 2-Benzoylpyridine;
M ) Pd, X ) F (3); M ) Pt, X ) F (4); M ) Pt, X ) Cl (5)]. A
typical preparation (3) was as follows. To a solution of 0.080 g (0.13
mmol) of cis-[Pd(C6F5)2(THF)2] in 20 mL of CH2Cl2 was added 0.025
g (0.13 mmol) of 2-benzoylpyridine. The yellow solution (red in the
case of the platinum complexes) was stirred at room temperature for 5
min and then evaporated to dryness. In order to eliminate completely
the THF, the residue was treated with 3 mL of CHCl3 and evaporated
to dryness. This operation was repeated 3 times, and finally, the residue
was treated with n-hexane, rendering 3 as a yellow solid (red for 4 and
5). Yields: 3, 83%; 4, 88%; 5, 70%.
Anal. Found (Calcd) for 3: N, 2.29 (2.25); C, 46.47 (46.22); H,
1.61 (1.45). IR, cm-1: C6F5 X-sensitive,6 805(s) and 799(s); others,
1632(m), 1500(vs), 1057(vs), and 959(vs); R-C(O)Ph, 1608(m),
1598(m), 1589(m), 1577(m), 1566(s), 1334(s), 1267(s), 1185(m),
1177(m), 1168(m), 1023(m), 820(m), 789(s), 772(m), 754(s), 700(s),
685(m), 664(m), and 649(m). 1H NMR (CDCl3, room temperature),
ppm: All the signals appear overlapped in the aromatic hydrogen
region. 19F NMR (CDCl3, room temperature), ppm: o-F, -116.31 (2F)
and -118.26 (2F); m-F, -163.05 (2F) and -164.15 (2F); p-F, -159.87
(1F) and -160.73 (1F).
NMR (HDA, room temperature), ppm: 7.58 (t, 2H); 7.75 (d, 2H), ≈7.8
3
(t, 1H); 7.96 (d, 1H); 8.05 (t, 1H); 8.40 (t, 1H); 9.50 (d, 1H, JPt-H
)
28 Hz). 19F NMR (HDA, room temperature), ppm: o-F, -117.82 (2F,
3JPt-F ) 403.0 Hz) and -119.19 (2F, 3JPt-F ) 483.6 Hz); m-F, -163.00
(2F) and -165.43 (2F); p-F, -160.09 (1F) and -162.01 (1F). 19F NMR
(HDA, -90 °C), ppm: o-F, -118.40 (1F), -119.47 (1F), -119.97
(1F), and -121.37 (1F) (due to the poor resolution it is not possible to
calculate the o-F-Pt coupling constants); m-F, -165.08 (4F); p-F,
-160.62 (1F) and -161.43 (1F).
cis-[Pt(C6F5)2{R-C(O)Ph}(PPh3)] (8). To a solution of 0.150 g
(0.211 mmol) of cis-[Pt(C6F5)2{R-C(O)Ph}], 4, in CH2Cl2 (20 mL)
0.055 g (0.211 mmol), of PPh3 was added. The red solution, which
immediately changed to colorless, was stirred at room temperature for
2 min and then evaporated to dryness. The resulting white solid, cis-
[Pt(C6F5)2{R-C(O)Ph}(PPh3)] (8), was washed with n-hexane (20 mL)
and was isolated in 85% yield.
Anal. Found (Calcd) for 4: N, 1.77 (1.97); C, 39.88 (40.46); H,
1.18 (1.27). IR, cm-1: C6F5 X-sensitive,6 819(s) and 814(s); others,
1636(m), 1503(vs), 1064(vs), and 959(vs); R-C(O)Ph, 1608(m),
1598(m), 1584(m), 1575(m), 1558(s), 1335(s), 1266(m), 1184(m),
1167(m), 1026(m), 806(s), 770(m), 754(s), 694(s), 683(m), 667(m),
and 651(m). 1H NMR (CDCl3, room temperature), ppm: 8.56 (d, 1H,
3JPt-H ) 28 Hz); the rest of the signals appear overlapped in the aromatic
Anal. Found (Calcd) for 8: N, 1.58 (1.44); C, 51.73 (51.76); H,
2.52 (2.48). IR, cm-1: C6F5 X-sensitive,6 787(s) and 775(s); others,
1638(m), 1503(vs), 1064(vs), and 956(vs); R-C(O)Ph, 1681(s), 1602(s),
1582(m), 1356(s), 1320(m), 1293(f), 1277(f), 1172(m), 1160(m),
1103(f), 1097(f), 1029(m), 940(f), 760(s), 698(s), 463(m), and 433(m);
PPh3, 807 (vs), 752(s), 740(s), 537(vs), 514(vs), and 494(s). 1H NMR
(HDA, room temperature), ppm: All signals except those corresponding
to the pyridinic ring appear overlapped in the zone of the aromatic
(6) Maslowsky, E., Jr. Vibrational Spectra of Organometallic Compounds;
3
Wiley: New York, 1977; p 437, and references given therein.
hydrogens; 8.82 (d, HR, JPt-H ) 26 Hz); 7.90 (t, Hâ); 7.19 (t, Hγ);

58 Inorganic Chemistry, Vol. 35, No. 1, 1996
Table 1. Crystallographic Data for 2‚1/4CHCl3 and 3
Casas et al.
Chart 1
complex
formula
molecular weight
space group
crystal system
a, Å
2
3
PtIF10NC18H6‚1/4CHCl3 PdF10NOC24H9
778.078
P1h
623.729
C2/c
monoclinic
26.284(3)
10.623(1)
31.423(4)
90
93.15(1)
90
8760(2)
16
triclinic
11.797(4)
13.735(4)
14.107(4)
97.24(2)
90.91(2)
99.44(2)
2235(2)
4
b, Å
c, Å
R, deg
â, deg
where P ) [max(Fo ,0) + 2Fc2]/3 and g ) 0.0400. A difference map
following convergence showed only one peak higher than 1 e/Å3 (1.08)
lying at 1.2 Å of the Pd(1) atom (minimum difference density of -0.55
e/Å3).
2
γ, deg
V, Å3
Z
crystal size, mm
d
0.40 × 0.63 × 0.65
0.56 × 0.40 × 0.24
calc, g/cm3
2.31
1.89
Results and Discussion
scan range, deg
scan mode
3 < 2θ < 50.7
ω
78.4
Mo KR (λR )
0.710 73 Å)
20 ( 2
4 < 2θ < 47
2θ/ω
9.5
Mo KR (λR )
0.710 73 Å)
20 ( 2
1.190
0.060
Reactions of cis-[M(C6F5)2(THF)2] (M ) Pd, Pt) with
2-Haloaniline (C6H6NX, X ) F, Cl, Br, I). In our attempts
to prepare complexes containing halocarbon ligands we have
used the 2-haloaniline family, C6H6NX (X ) F, Cl, Br, I; see
Chart 1a). The nitrogen atom of these ligands must displace
one of the THF groups of the starting material, leaving the
halogen atom suitably disposed to replace the second THF group
to establish a C-XfM bond. As mentioned above, the stability
of the halocarbon complex formed should be favored by the
chelating nature of the halocarbon ligand. Moreover, the higher
strength of the X-C (arene) bond can prevent the cleavage of
the C-X bond with oxidative addition to the metal center.
Thus, the reactions of complexes cis-[M(C6F5)2(THF)2] (M
) Pd, Pt) with 2-haloaniline have been carried out in a 1:1 molar
ratio using CH2Cl2 as a solvent. After 15 min of stirring, the
solvent is evaporated to dryness yielding a solid. Spectroscopic
and analytical data of the solids show that only for the
2-iodoaniline (R-I) the expected complexes, cis-[M(C6F5)2(R-
I)] [M ) Pd (1), Pt (2)], have been formed. For the other
2-haloanilines a mixture of compounds is obtained. We have
been unable to separate the components of this mixture in which,
in addition to the starting materials, the complexes cis-
[M(C6F5)2(C6H6NX)2] and cis-[M(C6F5)2(C6H6NX)(THF)] prob-
ably are present. Attempts to prepare the complexes cis-
[M(C6F5)2(C6H6NX)], analogous to 1 and 2, by changing
conditions such as reaction time or solvent have proved
unsuccessful.
µ(Mo KR), cm-1
radiation
temp, °C
goodness of fit on F2 1.312
R1[I > 2σ(I)]a
0.056
0.117
wR2[I > 2σ(I)]b
0.115
1.08/-1.55
final diff. peak/hole, 1.56/-2.19
e/Å3
a R ) ∑ | |Fo| - |Fc| | / ∑ |Fo|. b wR2 ) [∑[w(Fo - Fc2)2/
2
2
∑[w(Fo )2]1/2
.
7.54 (d, Hδ). 19F NMR (HDA, room temperature), ppm: o-F, -114.23
3
3
(1F, JPt-F ) 373.4), -116.02 (1F, JPt-F ) 351.4 Hz), -116.84 (1F,
3JPt-F ) 460.2 Hz), and -120.78 (1F, 3JPt-F ) 329.3 Hz); m-F, -163.83
(1F), -165.83 (1F), -165.94 (1F), and -166.69 (1F); p-F, -163.04
(1F) and -165.00 (1F).
Preparation of Crystals of 2 for X-ray Structure Determination.
Suitable crystals for X-ray purposes were obtained by slow diffusion
of n-hexane into a solution of 0.03 g of 2 in CH2Cl2 (4 mL) at -30 °C.
Crystal Data for Complex 2. Table 1 summarizes the crystal-
lographic data and least-squares residuals for the crystal structure of 2.
Diffraction data were measured by Crystalitics Company.7 An empirical
absorption correction was based on ψ-scan measurements. Six standard
reflections, which were remeasured after every 300 data points,
indicated that there was no decay. The structure was solved by direct
methods and refined on |Fo| using the SHELXL93 program.8 All of
2
the non-hydrogen atoms were refined anisotropically. All hydrogen
atoms were included in calculated positions and refined as riding atoms
[C-H, 0.96 Å and N-H, 0.90 Å] with their thermal parameters set up
to 1.2 times the Ueq value for the parent atoms. The chlorine atoms of
the solvent are disordered over two sites with a total occupancy of
0.25. The thermal parameters of each set of chlorine atoms have been
These results confirm the higher basicity of the iodine which
is able to compete successfully with the THF groups, leading
to the formation of the R-IfM bond.4c Even for the complexes
1 and 2, the presence in the NMR spectra of very small signals
could suggest the presence of some other complex such as cis-
[M(C6F5)2(R-I)2] (signals for THF are not observed) acting as
an impurity and worsening slightly the analytical data (see
Experimental Section).
constrained to be the same. Weights, w, were set equal to [σc2(Fo ) +
2
(gP)2]-1, where P ) [max(Fo ,0) + 2Fc2]/3 and g ) 0.0400.
A
2
difference map following convergence showed 17 peaks higher than 1
e/Å3 (1.56-1.01). These peaks lay very near the heavy atoms, and
they are most likely due to series termination or residual absorption
(minimum difference density of -2.19 e/Å3).
1
The H NMR spectra of 1 and 2 show only signals for the
R-I ligand. The signal corresponding to the amminic protons
is a singlet that, for complex 2, has platinum satellites because
of coupling with the 195Pt nucleus (2JPt-H ) 37 Hz). The
equivalence of the hydrogen nuclei for the NH2 fragment
indicates that a mirror plane is present in the molecule on the
NMR time scale. This mirror plane can also be inferred from
the 19F NMR spectra in which the two pentafluorophenyl groups
are inequivalent, displaying an AA′MM′X spin system.
Crystal Structure of the Complex cis-[Pt(C6F5)2(R-I)]‚
1/4CHCl3 (2‚1/4CHCl3). There are two molecules of 2 in the
crystallographic asymmetric unit. A drawing of these two
molecules (2a and 2b) showing the atom labeling scheme used
is depicted in Figure 1 (top and bottom, respectively). Selected
bond distances and angles for 2a and 2b are given in Table 2.
Fractional atomic coordinates and their estimated standard
deviation are listed in Table 3. The structural features of 2a
Preparation of Crystals of 3 for X-ray Structure Determination.
Suitable crystals for X-ray purposes were obtained by slow diffusion
of n-hexane into a solution of 0.03 g of 3 in CH2Cl2 (4 mL) at -30 °C.
Crystal Data for Complex 3. Table 1 summarizes the crystal-
lographic data and least-squares residuals for the crystal structure of 2.
Diffraction data for 3 were collected on a Siemens/STOE AED2 four-
circle diffractometer. An absorption correction based on ψ-scans was
applied. Three standard reflections were measured every 60 min
showing no decay. The structure was solved by direct methods and
2
refined on |Fo| using the SHELXL93 program.8 All of the non-
hydrogen atoms were refined anisotropically. All hydrogen atoms were
included in calculated positions and refined as riding atoms [C-H,
0.96 Å] with their thermal parameters set up to 1.2 times the Ueq value
2
for the parent atoms. Weights, w, were set equal to [σc2(Fo ) + (gP)2]-1
,
(7) Crystallytics Company, P.O. Box 82286, Lincoln, NE.
(8) Sheldrick, G. M. SHELXTL 93. J. Appl. Crystallogr., in press.

cis-[M(C6F5)2(NkX)]
Inorganic Chemistry, Vol. 35, No. 1, 1996 59
In addition, very few structures of iodocarbon complexes of
any transition metal can be found in the literature,11 and the
Pt-I distances found in 2a and 2b are shorter than any other
M-I-(C). In fact, these distances are similar or even shorter
than Pt-I distances found in complexes in which the iodine
ligand is acting in either a bridging or a terminal fashion.12 The
I-C distance and Pt-I-C angles in 2 are similar to those found
in other transition metal-iodocarbon ligand complexes.
Molecules 2a and 2b lie in parallel planes [the dihedral angle
between the two square-planar environments is 0.6(3)°]. The
amminic hydrogen atoms have been placed geometrically,
assuming an sp3 hybridization for the nitrogen and a N-H
distance of 0.90 Å. The distances between the platinum atom
of one molecule and one of the amminic hydrogen atoms of
the other are Pt(1)-H(2b) 2.79 Å and Pt(2)-H(1b) 2.79 Å, and
the angles Pt(1)-H(2b)-N(2) 161° and Pt(2)-H(1b)-N(1)
160° (see Figure 2). These short distances suggest that an
intermolecular Pt‚‚‚H interaction is present. The origin of such
interaction is due to the basic character of the metal center
(which is able to donate electron density from its 5dz2 orbital)
and the slightly weak acid characteristics of the amminic
hydrogen. There are few examples of this kind of interaction
MfH,13 which formally would possess a hydrogen-bonding
type of three center-four electron electronic configuration.
The existence of the Pt‚‚‚H interaction and concomitant
proximity of the two molecules require that the dihedral angles
between the best planes of the square-planar environment of
the platinum and the corresponding C6F5 groups take a value
lower (around 60°) than that usually found in other pentafluoro-
phenyl platinum(II) complexes (70-80°).9
There is no evidence of the presence of the Pt‚‚‚H interaction
in solution since, as previously mentioned, the 1H NMR
spectrum of 2 shows only one signal for both amminic hydrogen
atoms with 195Pt satellites due to the Pt-N bond. In any event,
the presence of the Pt‚‚‚H interaction in solution seems very
unlikely.
Reaction of cis-[M(C6X5)2(THF)2] (M ) Pd, Pt; X ) F,
Cl) with 2-Benzoylpyridine (C12H9NO, R-C(O)Ph). Reac-
tions identical to those described for the preparation of
complexes 1 and 2, but using the ligand 2-benzoylpyridine
(C12H9NO, R-C(O)Phssee Chart 1b), lead to the preparation
Figure 1. Drawing of the two molecules of complex 2 showing the
atom-labeling scheme.
Table 2. Selected Bond Distances and Angles for Complex 2
molecule 1
molecule 2
Distances (Å)
2.620(1) Pt(2)-I(2)
(9) Uso´n, R.; Fornie´s, J. AdV. Organomet. Chem. 1988, 288, 219, and
references given therein. Uso´n, R.; Fornie´s, J.; Toma´s, M. J.
Organomet. Chem. 1988, 358, 525, and references given therein. Uso´n,
R.; Fornie´s, J. Inorg. Chim. Acta 1992, 198-200, 165, and references
given therein.
(10) Albinati, A.; Pregosin, P. S.; Wombacher, F. Inorg. Chem. 1990, 29,
1812. Neve, F.; Ghedini, M.; de Munno, G.; Crispini, A. Organo-
metallics 1991, 10, 1143. Ryabov, A. D. Chem. ReV. 1990, 90, 403.
Albinati, A.; Anklin, C. G.; Ganazzoli, F.; Ru¨egg, H.; Pregosin, P. S.
Inorg. Chem. 1987, 26, 503. Crabtree, R. H.; Holt, E. M.; Lavin, M.;
Morehouse, S. H. Inorg. Chem. 1985, 24, 1986.
(11) Crabtree, R. H. ; Faller, J. W.; Mellea, M. F.; Quirk, J. M.
Organometallics 1982, 1, 1361. Winter, C. H.; Arif, A. M.; Gladysz,
J. A. J. Am. Chem. Soc. 1987, 109, 7560. Winter, C. H.; Veal, W. R.;
Garner, C. M.; Arif, A. M.; Gladysz, J. A. J. Am. Chem. Soc. 1989,
111, 4766. Burk, M. J.; Segmuller, B.; Crabtree, R. H. Organometallics
1987, 6, 2241. Conroy-Lewis, F. M.; Redhouse, A. D.; Simpson, S.
J. J. Organomet. Chem. 1989, 366, 357. Kulawiec, R. J.; Faller, J.
W.; Crabtree, R. H. Organometallics 1990, 9, 745. Powell, J.;
Horvath, M.; Lough, A. J. Chem. Soc., Chem. Commun. 1993, 733.
(12) van Beek, J. A. M.; van Koten, G.; Dekker, G. P. C. N.; Wissing, E.;
Zoutberg, M. C.; Stam, C. H. J. Organomet. Chem. 1990, 394, 659.
Abel, E. W.; Evans, D. G.; Koe, J. R. ; Hursthouse, M. B.; Madiz,
M.; Mahon, M. F.; Malloy, K. C. J. Chem. Soc., Dalton Trans. 1990,
1697. Stang, P. J.; Zong, Zh.; Kowalski, M. H. Organometallics 1990,
9, 833. Thiele, G.; Wagner, D. Chem. Ber. 1978, 111, 3162. Engelter,
C.; Moss, J. R.; Nassimbeni, L. R.; Niven, M. L.; Reid, G.; Spiers, J.
C. J. Organomet. Chem. 1986, 315, 255. Casas, J. M.; Falvello, L.
R.; Fornie´s, J.; Mart´ın, A.; Toma´s, M. J. Chem. Soc., Dalton Trans.
1993, 1107. O’Halloran, T. V.; Lippard, S. J.; Richmond, T. J.; Klug,
A. J. Mol. Biol. 1987, 194, 705.
Pt(1)-I(1)
2.610(1)
2.013(13)
1.981(13)
2.128(11)
2.092(14)
2.79(1)
Pt(1)-C(1)
Pt(1)-C(7)
Pt(1)-N(1)
I(1)-C(14)
Pt(1)‚‚‚H(2b)
1.990(13) Pt(2)-C(19)
1.990(13) Pt(2)-C(25)
2.132(12) Pt(2)-N(2)
2.101(15) I(2)-C(32)
2.77(1)
Angles (deg)
88.4(6) C(19)-Pt(2)-C(25) 89.0(6)
Pt(2)‚‚‚H(1b)
C(1)-Pt(1)-C(7)
C(1)-Pt(1)-N(1) 177.2(5)
C(7)-Pt(1)-N(1) 91.8(5)
C(19)-Pt(2)-N(2)
C(25)-Pt(2)-N(2)
I(2)-Pt(2)-C(19)
I(2)-Pt(2)-C(25)
I(2)-Pt(2)-N(2)
Pt(2)-I(2)-C(32)
177.9(5)
90.2(5)
96.7(4)
174.3(4)
84.1(3)
89.0(4)
I(1)-Pt(1)-C(1)
I(1)-Pt(1)-C(7)
I(1)-Pt(1)-N(1)
96.9(4)
174.7(4)
83.0(3)
Pt(1)-I(1)-C(14) 88.1(3)
and 2b are very similar. In both cases, the platinum atom has
a slightly distorted square-planar environment formed by the
two cis pentafluorophenyl groups and the iodoaniline which is
acting as a chelating didentate ligand. The Pt-Cipso distances
are in the range found in other pentafluorophenyl platinum
complexes.9 The Pt-N distances are also similar to those shown
in previously reported complexes.2i,10
The Pt-I distances are 2.620(1) Å for 2a and 2.610(1) Å for
2b. As far as we know, no structure containing a bond between
Pt and the iodine of an iodocarbon has previously been reported.

60 Inorganic Chemistry, Vol. 35, No. 1, 1996
Casas et al.
a
Table 3. Atomic Coordinates (×104) and Equivalent Isotropic Displacement Parameters (Å2 x 103) for 2‚1/4CHCl3
x
y
z
Ueq
x
y
z
Ueq
Pt(1)
Pt(2)
I(1)
1881(1)
1888(1)
1215(1)
4401(1)
908(1)
2417(1)
2709(1)
2302(1)
2717(1)
3498(10)
3475(11)
4237(13)
5072(12)
5135(11)
4378(11)
2677(6)
4145(9)
5815(8)
5963(6)
4496(6)
2421(11)
3199(11)
3182(12)
2433(14)
1609(12)
1637(10)
3987(6)
3967(8)
2426(8)
837(8)
836(6)
1224(9)
571(9)
872(10)
282(11)
-658(12)
-990(11)
-388(11)
1616(9)
694(10)
35(1)
33(1)
49(1)
44(1)
43(3)
56(4)
65(5)
70(5)
60(4)
52(4)
73(3)
105(4)
104(4)
84(3)
67(3)
46(4)
49(4)
57(4)
64(5)
62(5)
53(4)
64(3)
86(3)
89(4)
103(4)
79(3)
56(3)
40(3)
44(4)
55(4)
64(5)
70(5)
57(4)
37(3)
45(3)
C(21)
C(22)
C(23)
C(24)
F(20)
F(21)
F(22)
F(23)
F(24)
C(25)
C(26)
C(27)
C(28)
C(29)
C(30)
F(26)
F(27)
F(28)
F(29)
F(30)
N(2)
C(31)
C(32)
C(33)
C(34)
C(35)
C(36)
C(40)
Cl(1)
Cl(2)
Cl(3)
Cl(4)
Cl(5)
Cl(6)
1562(12)
2077(12)
2540(13)
2478(11)
946(8)
1070(9)
2103(9)
5358(12)
6324(12)
6759(11)
6183(11)
3876(6)
4938(7)
6880(8)
-42(9)
63(10)
938(11)
1679(9)
545(6)
47(4)
47(4)
51(4)
42(3)
62(2)
73(3)
74(3)
77(3)
65(3)
46(4)
49(4)
45(4)
60(5)
73(5)
57(4)
71(3)
69(3)
93(4)
102(4)
104(4)
46(3)
34(3)
43(3)
53(4)
64(5)
62(5)
45(3)
127(18)
135(6)
135(6)
135(6)
199(11)
199(11)
199(11)
-371(1)
-353(1)
2043(12)
2646(14)
2774(15)
2245(16)
1625(14)
1510(12)
3177(8)
I(2)
4016(1)
415(10)
-314(12)
-853(12)
-621(14)
125(13)
630(12)
-603(8)
-1581(9)
-1130(9)
375(8)
1361(7)
1543(11)
2051(11)
2271(12)
1937(14)
1421(14)
1246(13)
2412(7)
2784(8)
2145(9)
1106(10)
731(9)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
F(2)
F(3)
F(4)
F(5)
F(6)
C(7)
C(8)
C(9)
C(10)
C(11)
C(12)
F(8)
-905(6)
-658(6)
1076(7)
2535(6)
2804(11)
2094(11)
3595(10)
3692(12)
2980(14)
2177(13)
1308(7)
4316(6)
4466(7)
3084(9)
1469(9)
3898(8)
4494(9)
4127(9)
4677(11)
5630(11)
5994(11)
5423(9)
2054(15)
1317(17)
1540(20)
3201(14)
2465(24)
2241(27)
897(18)
3085(9)
2983(8)
7707(7)
6651(7)
3589(11)
4268(12)
4222(11)
5383(12)
6012(13)
5450(12)
3757(7)
3644(7)
5950(8)
7164(7)
6051(8)
1803(10)
819(10)
-227(12)
-1204(12)
-1101(15)
-59(14)
889(12)
5973(26)
6037(27)
6080(28)
6187(26)
7122(22)
6284(26)
5732(24)
4609(11)
4247(11)
5177(12)
5336(13)
4950(15)
4391(12)
3699(7)
5583(8)
5901(9)
5067(9)
4004(9)
3395(11)
2358(12)
1097(9)
894(8)
3588(11)
4242(12)
5433(12)
6002(12)
5362(13)
4195(12)
3755(7)
6037(8)
7158(7)
5930(9)
3636(8)
1706(10)
729(11)
-264(11)
-1281(12)
-1176(15)
-160(18)
776(14)
3584(9)
3572(9)
F(9)
3710(10)
3645(12)
3464(13)
3347(12)
3419(10)
7913(16)
6891(15)
8945(16)
7964(18)
7451(23)
9164(16)
7436(27)
F(10)
F(11)
F(12)
N(1)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
C(19)
C(20)
1996(9)
1660(10)
1184(10)
887(12)
1068(13)
1515(12)
1798(12)
5220(10)
4827(11)
1992(11)
1480(12)
a U(eq) is defined as one-third the trace of the orthogonalized Uij tensor.
electron density in the same way as the iodine atom in R-I.
Due to the higher basicity of the O atom with respect to the
phenyl group and the higher rigidity of the py-CO-Ph skeleton
in R-C(O)Ph than that of py-CH2-Ph, it is more likely that in
complexes 3-5 a bond Pt-OdC is present. Infrared spectra
of 3-5 confirm the existence of this bond since there is a
decrease in ν(CO) from 1671 cm-1 in the free ligand to about
1550 cm-1 in the complexes since the coordination of the
oxygen atom to the metal center causes the CO bond to
weaken.14
1
The most important feature in the H NMR spectra of 3-5
is the absence of signals for THF, which has been completely
displaced by the ligand R-C(O)Ph. 19F NMR spectra of 3 and
4 show the inequivalence of the two C6F5 groups, which appear
as AA′MM′X spin systems. Again, these spectra suggest the
existence of a symmetry plane on the NMR time scale that
would contain the square-planar environment of the metal atom.
Crystal Structure of Complex cis-[Pd(C6F5)2{R-C(O)Ph}]
(3). In this case, as for compound 2, there are two almost
identical molecules in the crystallographic asymmetric unit.
Figure 3 shows a drawing of both molecules (3a (left) and 3b
(right)) with the atom-labeling scheme. Tables 4 and 5 list
Figure 2. Perspective of the two molecules of complex 2 showing
the Pt-H interactions.
of the complexes cis-[M(C6F5)2{R-C(O)Ph}] [M ) Pd, X )
F (3); M ) Pt, X ) F (4), Cl (5)]. Compounds 3-5 are obtained
as strongly colored solids, yellow for the palladium and red for
the platinum complexes.
In a previous work we reported the preparation and structural
characterization of cis-[Pt(C6F5)2(R-CH2Ph)] (R-CH2Ph )
2-benzylpyridine; see Chart 1c) in which the four coordination
of the platinum center is achieved through an η2-phenyl-Pt
interaction.2i The ligand 2-benzoylpyridine is structurally
similar to bzpy. Nevertheless, for R-C(O)Ph, besides the
phenyl group there is also an oxygen atom that is able to donate
(13) Brammer, L.; Charnock, J. M.; Goggin, P. L.; Goodfellow, R. J.;
Orpen, A. G.; Koetzle, T. F. J. Chem. Soc., Dalton Trans. 1991, 1789.
Brammer, L.; McCann, M. C.; Bullock, R. M.; McMullan, R. K.;
Sherwood, P. Organometallics 1992, 11, 2339. Calderazzo, F.;
Fachinetti, G.; Marchetti, F.; Zanazzi, P. F. J. Chem. Soc., Chem.
Commun. 1981, 181. Wehman-Ooyevaar, I. C. M.; Grove, D. M.;
Kooijman, H.; van der Suis, P.; Spek, A. L.; van Koten, G. J. Am.
Chem. Soc 1992, 114, 9916.
(14) Allevi, C.; Della Pergola, R.; Garlaschelli, L.; Malatesta, M. C.;
Albinati, A.; Ganazzoli, F. J. Chem. Soc., Dalton Trans. 1988, 17.
Allevi, C.; Garlaschelli, L.; Malatesta, M. C.; Ganazzoli, F. Organo-
metallics 1990, 9, 1383, and references given therein.

cis-[M(C6F5)2(NkX)]
Inorganic Chemistry, Vol. 35, No. 1, 1996 61
ring be slightly distorted with respect to the ideal geometry
(O(1)-Pd(1)-N(1), 77.5(3)°; O(2)-Pd(2)-N(2), 77.0(3)°;
Pd(1)-N(1)-C(13), 114.3(6)°; Pd(2)-N(2)-C(37), 113.7(6)°).
Finally, 3a and 3b are almost coplanar (dihedral angle
6.3(2)°), but in this case no intermolecular interaction is
observed.
Reactivity of Complexes 1-5 toward Neutral and Anionic
Ligands. A proof of the weakness of the NkXfM bond is
obtained when neutral or anionic ligands are added to solutions
of complexes 1-5. In most of the cases, the new ligand L added
is able to displace the iodine or oxygen interaction forming a
new M-L bond. Thus, when CO is bubbled through a solution
of the iodocarbon complex 2 in CH2Cl2 for 5 min, the removal
of the solvent yields a solid that is identified as cis-[Pt(C6F5)2-
(R-I)(CO)] (6). The presence of the ligand CO coordinated
to the platinum center is confirmed by the infrared spectrum
that shows a sharp absorption at 2123 cm-1 corresponding to
ν(CO). Under the same conditions it is not possible to prepare
the analogous cis-[Pd(C6F5)2(R-I)(CO)]. Nevertheless, this
behavior is more likely due to the lack of stability of the Pd-
CO bond rather than to the strength of the NkXfPd one.2b
Figure 3. Drawing of the two molecules of complex 3 as they appear
in the crystal structure showing the atom-labeling scheme.
Table 4. Selected Bond Distances and Angles for 3
molecule 1
molecule 2
Distances (Å)
2.156(6) Pd(2)-O(2)
Pd(1)-O(1)
2.117(6)
1.988(8)
1.990(8)
2.103(7)
1.228(9)
Pd(1)-C(1)
Pd(1)-C(7)
Pd(1)-N(1)
C(18)-O(1)
2.012(9)
1.984(9)
2.099(7)
Pd(2)-C(25)
Pd(2)-C(31)
Pd(2)-N(2)
1
The H NMR spectrum of 6 shows that the ligand R-I is still
1.224(10) C(42)-O(2)
bonded to the metal atom because of the presence of 195Pt-1H
coupling in the amminic proton signal (2JPt-H ) 35 Hz). The
19F NMR spectrum indicates the presence of a molecular mirror
plane on the NMR time scale, even at -70 °C, since two
AA′MM′X spin systems are observed, one for each pentafluo-
rophenyl group.
If the bubbling of CO through solutions of 2 is maintained
over longer periods, the carbon monoxide is even able to
displace completely the ligand R-I, resulting in the formation
of cis-[Pt(C6F5)2(CO)2].2b Even in short duration reactions,
complex 6 is always impurified with small amounts of the bis-
(carbonyl) complex, the signals of which can be identified and
discarded in the NMR and infrared spectra.
Angles (deg)
C(1)-Pd(1)-C(7)
C(1)-Pd(1)-N(1)
C(7)-Pd(1)-N(1)
O(1)-Pd(1)-C(1)
O(1)-Pd(1)-C(7)
O(1)-Pd(1)-N(1)
Pd(1)-O(1)-C(18)
Pd(1)-N(1)-C(13)
Pd(1)-N(1)-C(17)
N(1)-C(13)-C(18)
O(1)-C(18)-C(13)
O(1)-C(18)-C(19)
88.3(4)
174.5(3)
97.1(3)
97.1(3)
174.1(3)
77.5(3)
113.3(6)
114.3(6)
127.6(6)
113.9(8)
120.6(8)
119.8(9)
C(25)-Pd(2)-C(31) 85.3(3)
C(31)-Pd(2)-N(2)
C(25)-Pd(2)-N(2)
O(2)-Pd(2)-C(31)
O(2)-Pd(2)-C(25)
O(2)-Pd(2)-N(2)
Pd(2)-O(2)-C(42)
Pd(2)-N(2)-C(37)
Pd(2)-N(2)-C(41)
N(2)-C(37)-C(42)
O(2)-C(42)-C(37)
O(2)-C(42)-C(43)
174.7(3)
99.2(3)
98.4(3)
176.1(3)
77.0(3)
117.6(6)
113.5(6)
126.2(7)
114.9(8)
116.4(8)
120.3(8)
C(13)-C(18)-C(19) 119.6(9)
C(37)-C(42)-C(43) 123.3(8)
The lability not only of the M-I bond but also of the M-N
bond in 1 and 2 becomes apparent once more in their reactions
with CH3CN and Br-. The addition of an excess of CH3CN to
solutions of 1 and 2 produces the complete displacement of the
iodoaniline ligand and the formation of the corresponding
complexes cis-[M(C6F5)2(CH3CN)2].17 If CH3CN is added in
a 1:1 molar ratio, a mixture of cis-[M(C6F5)2(CH3CN)2], cis-
[M(C6F5)2(R-I)(CH3CN)], and starting material is obtained.
Reaction of 2 with NBu4Br in a 1:1 molar ratio results in the
formation of [NBu4]2[Pt2(µ-Br)2(C6F5)4],18 also with elimination
of R-I due to the ability of the Br- to act as a bridging ligand.
The cleavage of the Pt-O bond in 4 is also easily induced
by CO and PPh3 ligands. When CO is bubbled or PPh3 is added
in a 1:1 molar ratio to solutions of 4 in CH2Cl2, the strong red
color fades almost instantaneously. The removal of the solvent
yields solids identified as cis-[Pt(C6F5)2{R-C(O)Ph}L] [L )
CO (7) or PPh3 (8)]. The presence of the new ligands in
complexes 7 and 8 is confirmed by their infrared spectra,
especially for the carbonyl complex for which a sharp ν(CO)
selected bond distances and angles and fractional atomic
coordinates with their estimated standard deviations.
In both molecules the palladium atom has a slightly distorted
square-planar environment formed by the two cis C6F5 groups
and the 2-benzoylpyridine ligand acting as a chelating didentate
ligand. The Pd-C9 and Pd-N2i,10 distances are in the range
found in similar compounds. The Pd(1)-O(1) and Pd(2)-O(2)
distances are 2.156(6) and 2.117(6) Å, respectively. These
values are similar or slightly higher than others found in Pd
complexes containing chelate ligands of the type PdsC∼CdO
or PdsN∼CdO.15 The C(18)sO(1) and C(42)sO(2) distances
are 1.224(10) and 1.228(9) Å, slightly shorter than those reported
in related complexes.15 The mean value given in the literature
for a CdO bond in CarsCOsCar surroundings in pure organic
compounds is 1.230 Å.16 From these values it is possible to
deduce that the coordination of the oxygen atom to the metal
center does not affect perceptibly the length of the C-O bond.
The five-membered rings formed by the Pd, O, and N atoms
and the two C atoms bonded to the latter [C(13) and C(18) for
3a and C(37) and C(42) for 3b] are almost perfectly planar and
are coplanar with the square-planar environment of the metal
(dihedral angles are 0.4(2)° for 3a and 1.0(2)° for 3b). This
structural feature, due to the characteristics of the R-C(O)Ph
ligand and its coordination in a chelate fashion, requires that
some angles around the atoms involved in the five-membered
absorption is observed at 2128 cm-1
. Moreover, for both
complexes the signal due to the ketonic group of the R-C(O)-
Ph ligand shows a displacement to higher frequencies (1681
cm-1) with respect to the starting complex 4 (1558 cm-1
)
indicating that the CdOfPt bond is no longer present. Again,
the preparation of the complex analogous to 7, cis-[Pd(C6F5)2-
{R-C(O)Ph}(CO)], is not possible under the same conditions
for the reasons mentioned above. It is also noteworthy that the
Pt-N(pyridine) bond is more robust than the Pt-N(aniline)
(15) Russell, D. R.; Tucker, P. A. J. Chem. Soc., Dalton Trans. 1975, 1743.
Brumbaugh, J. S.; Whittle, R. R.; Parvez, M.; Sen, A. Organometallics
1990, 9, 1735. Beck, W.; Schmidt, C.; Wienold, R.; Steimann, M.;
Wagner, B. Angew. Chem., Int. Ed. Engl. 1989, 28, 1529.
(16) Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen, A.
G.; Taylor, R. J. Chem. Soc., Perkin Trans. 2 1987, S-1.
(17) Mart´ın, A.; Rueda, A. J. Work in progress.
(18) Uso´n, R.; Fornie´s, J.; Toma´s, M.; Fandos, R. J. Organomet. Chem.
1984, 263, 253.

62 Inorganic Chemistry, Vol. 35, No. 1, 1996
Casas et al.
Table 5. Atomic Coordinates (×104) and Equivalent Isotropic Displacement Parameters (Å2 × 103) for 3a
x
y
z
Ueq
x
y
z
Ueq
Pd(1)
Pd(2)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
857(1)
1628(1)
1084(3)
1525(4)
1694(4)
1413(5)
959(4)
814(3)
829(3)
1248(3)
1237(4)
784(5)
343(4)
375(4)
627(3)
544(3)
412(3)
381(3)
492(3)
753(3)
707(3)
1103(4)
1078(4)
660(5)
250(5)
275(4)
1697(3)
1355(4)
1403(4)
1814(5)
2150(4)
2097(4)
1382(3)
920(3)
782(4)
1109(4)
1562(3)
10532(1)
2365(1)
9559(9)
8867(9)
8148(9)
199(1)
2125(1)
-306(3)
-278(3)
-607(3)
-982(3)
-1027(3)
-696(3)
-164(3)
-329(3)
-568(3)
-628(3)
-478(3)
-256(3)
1099(3)
1501(3)
1559(3)
1207(3)
813(3)
1000(3)
1332(3)
1395(3)
1708(3)
1947(4)
1872(3)
1569(3)
2623(3)
2692(3)
3042(3)
3327(3)
3268(3)
2923(3)
2536(3)
2737(3)
3027(3)
3142(3)
2952(3)
35(1)
35(1)
36(2)
42(3)
44(3)
51(3)
53(3)
44(3)
38(2)
41(2)
47(3)
58(3)
57(3)
47(3)
36(2)
39(2)
47(3)
41(2)
41(2)
42(2)
38(2)
49(3)
61(3)
65(3)
67(3)
57(3)
33(2)
46(3)
54(3)
56(3)
52(3)
41(2)
30(2)
37(2)
47(3)
43(2)
41(2)
C(36)
C(37)
C(38)
C(39)
C(40)
C(41)
C(42)
C(43)
C(44)
C(45)
C(46)
C(47)
C(48)
F(2)
F(3)
F(4)
F(5)
F(6)
F(8)
F(9)
F(10)
F(11)
F(12)
F(26)
F(27)
F(28)
F(29)
F(30)
F(32)
F(33)
F(34)
F(35)
F(36)
O(1)
1682(3)
1917(3)
2044(3)
2203(4)
2230(4)
2064(4)
1754(3)
1790(3)
2203(4)
2219(5)
1861(5)
1451(4)
1429(4)
1821(2)
2148(2)
1560(3)
680(2)
4634(9)
1716(9)
1005(9)
-225(10)
-694(10)
17(10)
2655(3)
1264(3)
920(3)
38(2)
36(2)
42(3)
50(3)
51(3)
45(3)
35(2)
35(2)
50(3)
64(3)
72(4)
64(3)
45(3)
52(2)
67(2)
76(2)
83(2)
65(2)
59(2)
73(2)
84(2)
85(2)
62(2)
73(2)
92(2)
88(2)
74(2)
57(2)
54(2)
65(2)
64(2)
70(2)
59(2)
43(2)
42(2)
34(2)
34(2)
974(3)
1379(3)
1714(3)
1245(3)
867(3)
602(3)
270(3)
194(3)
457(3)
795(3)
91(2)
-563(2)
-1305(2)
-1397(2)
-763(2)
-262(2)
-715(2)
-845(2)
-546(2)
-109(2)
2413(2)
3091(2)
3670(2)
3564(2)
2889(2)
2643(2)
3205(2)
3435(2)
3059(2)
2479(2)
649(2)
8089(10)
8751(11)
9479(10)
12062(8)
12610(9)
13701(10)
14316(10)
13809(11)
12682(10)
10611(9)
11031(9)
12302(10)
13067(9)
12591(9)
9287(9)
8300(9)
7433(9)
6530(10)
6448(10)
7262(11)
8201(11)
1214(8)
3067(9)
3852(8)
3754(10)
4576(11)
5489(12)
5597(10)
4789(9)
8876(5)
7527(5)
7353(6)
8707(7)
10123(6)
12048(5)
14185(6)
15412(6)
14415(6)
12250(5)
87(6)
C(8)
C(9)
C(10)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
C(19)
C(20)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
C(27)
C(28)
C(29)
C(30)
C(31)
C(32)
C(33)
C(34)
C(35)
374(2)
1713(2)
1660(2)
752(3)
-103(2)
-67(2)
954(2)
1046(3)
1848(3)
2544(2)
2454(2)
586(2)
328(2)
975(2)
1883(2)
2140(2)
898(2)
1588(2)
625(3)
-1404(7)
-1162(6)
692(6)
263(9)
2228(5)
2635(5)
4378(5)
6276(5)
6462(5)
4768(5)
9000(6)
3506(6)
11386(7)
1180(7)
-514(10)
-376(11)
547(11)
1334(9)
3620(8)
3582(9)
4458(9)
5432(9)
5524(9)
O(2)
N(1)
N(2)
1572(2)
758(2)
1658(2)
1916(3)
a U(eq) is defined as one-third the trace of the orthogonalized Uij tensor.
since the ligand R-C(O)Ph is not completely displaced from
complex 4 when CO is bubbled through its solutions for longer
periods.
because of the limited basic character of the halogen atoms.
This characteristic has been confirmed in this work since only
for a haloaniline containing iodine is it possible to prepare and
isolate the corresponding complex cis-[M(C6F5)2(R-I)] [M )
Pd (1) or Pt (2)] because of the more basic nature of the iodine
atom with respect to the other halogens. Complexes 1 and 2
are among the very few known halocarbon complexes of Pd
and Pt. In any case, the M-I bonds in 1 and 2 are weak and
easily broken by the addition of ligands such as CO, CH3CN,
or Br-. The ketonic oxygen atom of the ligand 2-benzoyl-
pyridine acts in a similar way as the iodine atom in R-I, which
allows the synthesis of the complexes cis-[M(C6F5)2{R-
C(O)Ph}] [M ) Pd, X ) F (3); M ) Pt, X ) F (4), Cl (5)].
Also, the M-O bond is easily displaced by the addition of
ligands such as CO or PPh3.
The NMR spectra of 7 show a dynamic behavior for this
complex in solution. In the 1H NMR spectrum at room
temperature all the hydrogen nuclei of the R-C(O)Ph phenyl
group in homologous positions are equivalent probably because
it rotates about the C(O)-Cipso bond. This rotation is not
stopped even at -90 °C. The 19F NMR spectrum at room
temperature shows one AA′MM′X spin system for each penta-
fluorophenyl group. However, at -90 °C the spectrum shows
two AFMRX spin systems since all the fluorine nuclei are
inequivalent. These spectra suggest that the C6F5 groups rotate
at room temperature and that at -90 °C this rotation is stopped
or slow enough for the NMR technique to distinguish all the
different fluorine nuclei. The 19F NMR spectrum of 8 at room
temperature shows the signals for two AFMRX spin systems,
indicating that in this complex the C6F5 groups do not rotate
probably because the triphenylphospine ligand is bulkier than
carbon monoxide.
Acknowledgment. We thank the Comisio´n Interministerial
de Ciencia y Tecnolog´ıa (Spain) for financial support (project
PB92-0364) and for a Formacio´n de Personal Investigador
(F.P.I.) grant to A.M.
Conclusions
Supporting Information Available: For the crystal structures of
2 and 3, tables of crystal data and structure refinement, anisotropic
displacement parameters, full tables of bond distances and angles, and
tables of coordinates and isotropic thermal parameters for the hydrogen
atoms (15 pages). Ordering information is available on any current
masthead page.
The behavior of the “cis-M(C6X5)2” fragment as a moderate
Lewis acid makes possible the use of the substrates cis-
[M(C6X5)2(THF)2] in the preparation of complexes containing
unusual NkXfM bonds. The family of 2-haloanilines has been
used for this purpose as nucleophiles. The number of known
complexes containing halocarbon ligands is small mainly
IC950283+