Synthesis and reactivity of dinuclear complexes containing η2-phenyl-metal interactions. Crystal structures of [NBu4][(C6F5)3Pt{μ-Ph 2PCH2PPh(eta;2-Ph)}Pt(C6F 5)2]

Article abstract of DOI:10.1021/ic9808753

Reaction between [NBu₄][Pt(C₆F₅)₃(dppm-κ ¹P)] and cis-[M(C₆X₅)₂(thf)₂] (M = Pt, Pd; X = F, Cl; thf = tetrahydrofuran) leads to dinuclear derivatives with dppm ligands bridging two metal centers: [NBu₄][(C₆F₅)₃-Pt{μ-Ph ₂PCH₂PPh(η²-Ph)}M(C₆X ₅)2] [X = F, M = Pt (1), M = Pd (2); X = Cl, M = Pt (3), M = Pd (4)]. The structural characterization of complex 1 by single-crystal X-ray diffraction (orthorhombic system, space group Fdd2, with a = 26.520(7) A?, b = 83.69(3) A?, c = 13.835(5) A?, V = 30706(11) A?³, and Z = 16) reveals two square-planar platinum(II) fragments sharing a dppm ligand with a η²-phenyl-platinum interaction between a phenyl ring of the dppm ligand and one platinum center. This weak η²-phenyl-platinum interaction can be easily displaced by addition of ligands such as CO (giving complex 5), PPh₃ (6), or p-toluidine (7). The structure of 5 was determined by single-crystal X-ray diffraction. It crystallizes in the monoclinic system, space group Pn, with a = 12.259(2) A?,b = 16.375(3) A?, c = 18.851(4) A?, β = 100.99(3)°, V = 3714.8 A°³, and Z = 2. The complex consists of two square-planar platinum(II) fragments with the dppm ligand acting as a conventional bridge.

Full text of DOI:10.1021/ic9808753

Inorg. Chem. 1999, 38, 1529-1534
1529
Synthesis and Reactivity of Dinuclear Complexes Containing η2-Phenyl-Metal Interactions.
Crystal Structures of [NBu4][(C6F5)3Pt{µ-Ph2PCH2PPh(η2-Ph)}Pt(C6F5)2] and
[NBu4][(C6F5)3Pt(µ-dppm)Pt(C6F5)2(CO)]
Jose´ M. Casas, Juan Fornie´s,* Francisco Mart´ınez, Angel J. Rueda, and Milagros Toma´s
Departamento de Qu´ımica Inorga´nica, Instituto de Ciencia de Materiales de Arago´n,
Universidad de Zaragoza-CSIC, E-50009 Zaragoza, Spain
Alan J. Welch
Department of Chemistry, Heriot-Watt University, Edinburgh EH14 4AS, U.K.
ReceiVed July 24, 1998
Reaction between [NBu4][Pt(C6F5)3(dppm-κ1P)] and cis-[M(C6X5)2(thf)2] (M ) Pt, Pd; X ) F, Cl; thf )
tetrahydrofuran) leads to dinuclear derivatives with dppm ligands bridging two metal centers: [NBu4][(C6F5)3-
Pt{µ-Ph2PCH2PPh(η2-Ph)}M(C6X5)2] [X ) F, M ) Pt (1), M ) Pd (2); X ) Cl, M ) Pt (3), M ) Pd (4)]. The
structural characterization of complex 1 by single-crystal X-ray diffraction (orthorhombic system, space group
Fdd2, with a ) 26.520(7) Å, b ) 83.69(3) Å, c ) 13.835(5) Å, V ) 30706(11) Å3, and Z ) 16) reveals two
square-planar platinum(II) fragments sharing a dppm ligand with a η2-phenyl-platinum interaction between a
phenyl ring of the dppm ligand and one platinum center. This weak η2-phenyl-platinum interaction can be easily
displaced by addition of ligands such as CO (giving complex 5), PPh3 (6), or p-toluidine (7). The structure of 5
was determined by single-crystal X-ray diffraction. It crystallizes in the monoclinic system, space group Pn, with
a ) 12.259(2) Å, b ) 16.375(3) Å, c ) 18.851(4) Å, â ) 100.99(3)°, V ) 3714.8 Å3, and Z ) 2. The complex
consists of two square-planar platinum(II) fragments with the dppm ligand acting as a conventional bridge.
Introduction
(dppm-κ1P)] and cis-[M(C6F5)2(thf)2] with the aim of preparing
binuclear complexes with PtfM bonds based on the following
ideas:
Bis(diphenylphosphino)methane (dppm) is a much-used
ligand, mainly because of its ability to facilitate the synthesis
of homo- or heterometallic polynuclear bridged complexes. The
structure and flexibility of this phosphine make it adequately
suited to bridge two metal centers which are involved in metal-
metal bonds, although there exists a large number of complexes
in which the dppm ligand bridges metal centers not involved
in metal-metal interactions or acts as a chelating or monoden-
tate ligand.1-3
In the course of our current research we are studying the basic
properties of pentafluorophenyl-containing platinate complexes
toward metal complexes or metal salts (M ) Ag, Pb, Tl, Hg)4
which should allow the formation of polynuclear complexes with
PtfM (donor-acceptor) bonds. In this context we considered
it of interest to study the reaction between [NBu4][Pt(C6F5)3-
(a) [NBu4][Pt(C6F5)3(dppm-κ1P)] can function as a bidentate
metalloligand with the P and Pt atoms acting as donors.
(b) cis-[M(C6X5)2(thf)2] (M ) Pt, Pd; X ) F, Cl) are
appropriate substrates with which to utilize the bidentate
behavior of the above anionic platinum complex because of the
well-documented lability of both thf ligands.5 Assuming that
both reagents react as expected, the reaction should give (eq 1)
the dinuclear compounds having perpendicular metal coordina-
tion planes and a PtfM donor-acceptor bond.6
This paper reports the results of such reactions. Binuclear
compounds of the expected stoichiometry are produced, but
without a PtfM bond. Instead, a η2-phenyl-Pt interaction
results.
Experimental Section
(1) Puddephatt, R. J. Chem. Soc. ReV. 1983, 12, 99.
General Methods. C, H, and N analyses were carried out with a
Perkin-Elmer 240B microanalyzer. IR spectra were recorded over the
4000-200 cm-1 range on a Perkin-Elmer 883 spectrophotometer using
Nujol mulls between polyethylene sheets. 1H, 19F, and 31P NMR spectra
(2) Chaudret, B.; Delavaux, B.; Poilblanc, R. Coord. Chem. ReV. 1988,
86, 191.
(3) Anderson, G. K. AdV. Organomet. Chem. 1993, 35, 1.
(4) (a) Uso´n, R.; Fornie´s, J. Inorg. Chim. Acta 1992, 198-200, 219. (b)
Cotton, F. A.; Falvello, L. R.; Uso´n, R.; Fornie´s, J.; Toma´s, M.; Casas,
J. M.; Ara, I. Inorg. Chem. 1987, 26, 1366. (c) Uso´n, R.; Fornie´s, J.;
Toma´s, M.; Ara, I.; Casas, J. M.; Mart´ın, A. J. Chem. Soc., Dalton
Trans. 1991, 2253. (d) Uso´n, R.; Fornie´s, J.; Falvello, L. R.; Uso´n,
M. A.; Uso´n, I. Inorg. Chem. 1992, 31, 3697. (e) Casas, J. M.; Fornie´s,
J. Mart´ın, A.; Orera, V. M.; Orpen, A. G.; Rueda, A. J. Inorg. Chem.
1995, 34, 6514. (f) Uso´n, R.; Fornie´s, J.; Toma´s, M.; Garde, R.;
Merino, R. Inorg. Chem. 1997, 36, 1383. (g) Ara, I.; Berenguer, J.
R.; Fornie´s, J.; Go´mez, J.; Lalinde, E.; Merino, R. I. Inorg. Chem.
1997, 36, 6461. (h) Uso´n, R.; Fornie´s, J.; Falvello, L. R.; Ara, I.; Uso´n,
I. Inorg. Chim. Acta 1993, 212, 105. (i) Falvello, L. R.; Fornie´s, J.;
Mart´ın, A.; Navarro, R.; Sicilia, V.; Villarroya, P. Inorg. Chem. 1997,
36, 6166.
(5) (a) Uso´n, R.; Fornie´s, J.; Toma´s, M.; Menjo´n, B.; Welch, A. J.
Organometallics 1988, 7, 1318. (b) Uso´n, R.; Fornie´s, J.; Toma´s, M.;
Menjo´n, B.; Navarro, R.; Carnicer, J. Inorg. Chim. Acta 1989, 162,
33. (c) Uso´n, R.; Fornie´s, J.; Toma´s, M.; Casas, J. M.; Navarro, R. J.
Chem. Soc., Dalton Trans. 1989, 169. (d) Uso´n, R.; Fornie´s, J.; Toma´s,
M.; Menjo´n, B.; Carnicer, J.; Welch, A. J. J. J. Chem. Soc., Dalton
Trans. 1990, 151.
(6) (a) Krumm, M.; Lippert, B.; Randaccio, L.; Zangrado, E. J. Am. Chem.
Soc. 1991, 113, 5129. (b) Krumm, M.; Zangrado, E.; Randaccio, L.;
Menzer, S.; Lippert, B. Inorg. Chem. 1993, 32, 700. (c) So`va`go´, I.;
Kiss, A.; Lippert, B. J. Chem. Soc., Dalton Trans. 1995, 489. Ladd,
J. A.; Olmstead, M. M.; Balch, A. L. Inorg. Chem. 1984, 23, 2318.
10.1021/ic9808753 CCC: $18.00 © 1999 American Chemical Society
Published on Web 03/16/1999

1530 Inorganic Chemistry, Vol. 38, No. 7, 1999
Casas et al.
1
at room temperature were recorded on a Varian XL-200 or a Unity-
956 s; dppm, 694 m, 534 m, 516 m, 484 m. H NMR (CDCl3): δ 7.2
(br, 20H, aromatic), 3.2 (m, 2H, CH2). 19F NMR (CDCl3): δ -116.2
(mc, 6F, o-F), -166.4 (br, 9F, 6 m-F + 3 p-F). 31P NMR (CDCl3): δ
18.8 [1J(195Pt,P) ) 2685 Hz], 24.7 [1J(195Pt,P) ) 2195 Hz].
1
300 spectrometer in CDCl3 or HDA solutions. H, 19F, and 31P NMR
spectra at low and variable temperature were recorded in CD2Cl2
1
solutions on a Bru¨ker ARX-300 spectrometer, also the H NMR and
[NBu4][(C6F5)3Pt{µ-Ph2PCH2PPh(η2-Ph)}Pd(C6Cl5)2] (4). To a
solution of [NBu4][Pt(C6F5)3(dppm-κ1P)] (0.200 g, 0.151 mmol) in CH2-
Cl2 (15 mL) was added cis-[Pd(C6Cl5)2(thf)2] (0.113 g, 0.151 mmol)
(molar ratio 1:1). After 5 min stirring at room temperature, the solution
was evaporated to dryness and the residue was treated with CHCl3 (5
mL) and evaporated to dryness again. Upon addition of n-hexane (20
mL) a pale yellow solid (4) was obtained, filtered off, and washed with
n-hexane. Yield: 76%. Anal. Found (Calcd for C71H58Cl10F15N1P2-
PdPt): C, 44.07 (44.24); H, 2.93 (3.01); N, 0.75 (0.73).
the COSY experiments at -40 °C were recorded on a Bru¨ker DMX-
500 spectrometer. Negative ion FAB mass spectra were recorded on a
VG-Autospec spectrometer operating at ca. 30 kV, using the standard
cesium ion FAB gun and 3-nitrobenzyl alcohol as matrix. [NBu4][Pt-
(C6F5)3(dppm-κ1P)],7 cis-[M(C6F5)2(thf)2] (M ) Pd, Pt),8 and dppm9
were prepared as described elsewhere.
[NBu4][(C6F5)3Pt{µ-Ph2PCH2PPh(η2-Ph)}Pt(C6F5)2] (1). To a
solution of [NBu4][Pt(C6F5)3(dppm-κ1P)] (0.400 g, 0.302 mmol) in CH2-
Cl2 (30 mL) was added cis-[Pt(C6F5)2(thf)2] (0.203 g, 0.302 mmol)
(molar ratio 1:1). After 10 min stirring at room temperature, the solution
was evaporated to dryness and the residue was treated with CHCl3 (5
mL) and evaporated to dryness again. Upon addition of n-hexane (20
mL) and after 30 min of stirring a white solid (1) was obtained, which
was filtered off and washed with n-hexane. Yield: 71%. Anal. Found
(Calcd for C71H58F25N1P2Pt2): C, 45.19 (46.03); H, 3.11 (3.15); N, 0.72
(0.75).
IR (cm-1): C6F5 X-sensitive mode,10 840 m, 823 m; others, 1633
1
w, 1467 vs, 1055 s, 957 s; dppm, 693 m, 536 w, 511 w, 485 w. H
NMR (CDCl3): δ 7.2 (br, 20H, aromatic), 2.9 (m, 2H, CH2). 19F NMR
(CDCl3): δ -115.9 (br, 6F, o-F), -166.2 (br, 9F, 6 m-F + 3 p-F). 31
P
NMR (CDCl3): δ 20.2, 11.2 [1J(195Pt,P) ) 2602 Hz].
[NBu4][(C6F5)3Pt(µ-dppm)Pt(C6F5)2(CO)] (5). A CH2Cl2 solution
of [NBu4][Pt2(C6F5)5(dppm)] (1, 0.150 g, 0.081 mmol) was reacted with
carbon monoxide. After 5 min of stirring at room temperature under a
carbon monoxide atmosphere, the solution was evaporated to dryness
and the residue was treated with n-hexane (20 mL) to render a white
solid (5), which was filtered off. Yield: 79%. Anal. Found (Calcd for
C72H58F25N1O1P2Pt2): C, 45.80 (45.99); H, 3.20 (3.08); N, 0.90 (0.74).
FAB- MS: m/z 1637 [Pt2(C6F5)5(dppm)(CO)]-. IR (cm-1): C6F5
X-sensitive mode,10 794 m; others, 1636 w, 1607 w, 1498 s, 1465 vs,
1064 s, 956 s; dppm, 693 m, 534 m, 515 m, 483 m; ν(CO), 2109 s. 1H
NMR (acetone-d6): δ 7.7 (mc, 4H, aromatic), 7.3 (mc, 4H, aromatic),
7.2 (mc, 8H, aromatic), 7.0 (mc, 4H, aromatic), 3.8 (m, 2H, CH2). 19F
FAB- MS: m/z 1609 [Pt2(C6F5)5(dppm)]-. IR (cm-1): C6F5 X-
sensitive mode,10 804 m, 773 m; others, 1635 w, 1607 w, 1499 vs,
1
1058 s, 958 s; dppm: 696 m, 535 m, 513 m, 493 w. H NMR room
temperature (CDCl3): δ 7.3 (br, 20H, aromatic), 3.6 (m, 2H, CH2).1H
NMR (CD2Cl2, -40 °C): δ 9.48 (dd, 2H, o-H, Ph-b), 8.00 (dd, 2H,
o-H, Ph-c), 7.86 (t-br, 1H, m-H, Ph-a), 7.74 (t, 1H, p-H, Ph-b), 7.64
(m, 5H, -m-H, Ph-b- and -m-H, Ph-c- and -p-H, Ph-c-), 7.17 (t, 1H,
p-H, Ph-d), 7.12 (t, 1H, o-H, Ph-a), 6.83 (t, 2H, m-H, Ph-d), 6.77 (t,
1H, o-H, Ph-a), 6.74 (t, 1H, o-H, Ph-a), 6.13 (t, 1H, m-H, Ph-a), 6.08
(dd, 2H, o-H, Ph-d), 3.51 (m, 1H, CH2) ), 3.30 (m, 1H, CH2). 19F NMR
(CDCl3): δ -115.4 (mc, 10F, o-F), -164.6 (br, 4F, m-F), -165.4 (br,
4F, m-F), -166.5 (br, 2F, m-F), -162.3 (t, 1F, p-F), -163.2 (t, 1F,
p-F), -165.7 (mc, 2F, p-F), -166.0 (t, 1F, p-F). 31P NMR (CDCl3): δ
22.4 [1J(195Pt2,P2) ) 2648 Hz], 26.2 [1J(195Pt1,P1) ) 2379 Hz].
[NBu4][(C6F5)3Pt{µ-Ph2PCH2PPh(η2-Ph)}Pd(C6F5)2] (2). To a
solution of [NBu4][Pt(C6F5)3(dppm-κ1P)] (0.200 g, 0.151 mmol) in CH2-
Cl2 (15 mL) was added cis-[Pd(C6F5)2(thf)2] (0.088 g, 0.151 mmol)
(molar ratio 1:1). After 25 min of stirring at room temperature, the
solution was evaporated to dryness and the residue was treated with
CHCl3 (5 mL) and evaporated to dryness again. Upon addition of
n-hexane (20 mL) a white solid (2) was obtained, filtered off, and
washed with n-hexane. Yield: 86%. Anal. Found (Calcd for C71H58-
F25N1P2PdPt with a CHCl3 molecule): C, 45.27 (45.93); H, 3.14 (3.08);
N, 0.74 (0.74).
3
NMR (acetone-d6): δ -116.2 [mc, J(195Pt,F) ) 332.1 Hz, 4F, o-F],
3
-117.1 (br, 2F, o-F), -118.5 [mc, J(195Pt,F) ) 322.4 Hz, 2F, o-F],
3
-119.5 [mc, J(195Pt,F) ) 349.8 Hz, 2F, o-F], -162.0 (mc, 1F, p-F),
-163.7 (mc, 1F, p-F), -165.5 (mc, 2F, m-F), -166.0 (mc, 2F, m-F),
-168.0 (mc, 6F, 2 p-F + 4 m-F), -168.3 (mc, 1F, p-F), -168.7 (mc,
2F, m-F). 31P NMR (acetone-d6): δ 7.6 [1J(195Pt,P) ) 2611 Hz], 3.0
[1J(195Pt,P) ) 2194 Hz].
[NBu4][(C6F5)3Pt(µ-dppm)Pt(C6F5)2(PPh3)] (6). To a solution of
[NBu4][Pt2(C6F5)5(dppm)] (1, 0.150 g, 0.081 mmol) in CH2Cl2 (30 mL)
was added PPh3 (0.021 g, 0.081 mmol) (molar ratio 1:1). After 15 min
of stirring at room temperature, the solution was evaporated to dryness
and the residue was treated with OEt2 (20 mL) to render a white solid
(6), which was filtered off. Yield: 76%. Anal. Found (Calcd for
C89H73F25N1P3Pt2): C, 50.25 (50.55); H, 3.63 (3.48); N, 0.64 (0.66).
FAB- MS: m/z 1877 [Pt2(C6F5)5(dppm)(PPh3)]-. IR (cm-1): C6F5
X-sensitive mode,10 848 m, 794 m; others, 1633 w, 1606 w, 1498 s,
1465 vs, 1098 s, 957 s; dppm, 697 m, 538 m, 509 m, 484 m; PPh3,
743 m. 1H NMR (CDCl3): δ 7.0 (br, 35H, aromatic), 3.4 (br, 2H, CH2).
19F NMR (CDCl3): δ -116.2 (br, 6F, o-F), -117.1 (br, 2F, o-F),
FAB- MS: m/z 1521 [PtPd(C6F5)5(dppm)]-. IR (cm-1): C6F5
X-sensitive mode,10 848 m, 800 m, 791 m; others, 1606 w, 1467 s,
1
1055 m, 958 s; dppm: 696 m, 535 m, 513 m, 493 w. H NMR (CD2-
Cl2): δ 7.3 (br, 20H, aromatic), 3.4 (m, 2H, CH2). 19F NMR (CD2Cl2):
δ -113.1 (br, 2F, o-F), -114.0 (br, 6F, o-F), -115.0 (br, 2F, o-F),
-158.9 (t, 1F, p-F), -161.0 (t, 1F, p-F), -161.3 (mc, 2F, m-F), -162.5
(mc, 2F, m-F), -164.5 (br, 9F, 6 m-F + 3 p-F). 31P NMR (CD2Cl2):
δ 20.4 [1J(195Pt,P) ) 2648 Hz], 23.8.
3
-118.6 [br, J(195Pt,F) ) 310.6 Hz, 2F, o-F], -162.0 (br, 1F, p-F),
-163.0 (mc, 2F, m-F), -164.0 (br, 1F, p-F), -164.7 (br, 2F, m-F),
-166.4 (br, 9F, 3 p-F + 6 m-F). 31P NMR (CDCl3): δ 14.3 [1J(195Pt,P)
) 2430 Hz], 13.6 [1J(195Pt,P) ) 2642 Hz], 4.0 [1J(195Pt,P) ) 2317 Hz].
[NBu4][(C6F5)3Pt(µ-dppm)Pd(C6F5)2(p-toluidine)] (7). To a solu-
tion of [NBu4][PtPd (C6F5)5(dppm)] (4, 0.266 g, 0.151 mmol) in CH2-
Cl2 (30 mL) was added p-toluidine (0.016 g, 0.151 mmol) (molar ratio
1:1). After 1 h of stirring at room temperature, the solution was
evaporated to dryness and the residue was treated with iPrOH (20 mL)
to render a white solid (7), which was filtered off and washed with
n-hexane. Yield: 71%. Anal. Found (Calcd for C78H67F25N2P2PdPt):
C, 50.18 (50.09); H, 4.03 (3.61); N, 1.64 (1.50).
[NBu4][(C6F5)3Pt{µ-Ph2PCH2PPh(η2-Ph)}Pt(C6Cl5)2] (3). To a
solution of [NBu4][Pt(C6F5)3(dppm-κ1P)] (0.400 g, 0.302 mmol) in CH2-
Cl2 (30 mL) was added cis-[Pt(C6Cl5)2(thf)2] (0.253 g, 0.302 mmol)
(molar ratio 1:1). The solution quickly turned pale yellow. After 5 min
stirring at room temperature, the solution was evaporated to dryness
and the residue was treated with CHCl3 (5 mL) and evaporated to
dryness again. Upon addition of n-hexane and after 30 min of stirring
(20 mL) a pale yellow solid (3) was obtained, filtered off, and washed
with n-hexane. Yield: 94%. Anal. Found (Calcd for C71H58Cl10F15N1P2-
Pt2): C, 42.65 (42.30); H, 2.72 (2.90); N, 0.69 (0.70).
IR (cm-1): C6F5 X-sensitive mode,10 818 m, 785 m; others, 1636
w, 1608 w, 1499 s, 1463 vs, 1097 s, 957 s; dppm, 534 m, 498 m;
FAB- MS: m/z 1773 [Pt2(C6F5)3(C6Cl5)2(dppm)]-. IR (cm-1): C6F5
X-sensitive mode,10 835 m, 803 m; others, 1633 w, 1465 vs, 1057 s,
1
p-tol, 3348 w. H NMR (CDCl3): δ 7.1 (mc, 24H, aromatic), 3.4 (br,
2H, CH2), 2.2 (br, 2H, NH2), 1.6 (s, 3H, CH3). 19F NMR (CDCl3): δ
-116.0 (mc, 10F, o-F), -166.0 (br, 15F, 5 p-F + 10 m-F). 31P NMR
(CDCl3): δ 20.1, 7.3 [1J(195Pt,P) ) 2595 Hz].
(7) Uso´n, R.; Fornie´s, J.; Toma´s, M.; Fandos, R. J. Organomet. Chem.
1984, 263, 253.
(8) Uso´n, R.; Fornie´s, J.; Toma´s, M.; Menjo´n, B. Organometallics 1985,
4, 1912.
(9) Aguiar, A. M.; Beisler, J. J. Org. Chem. 1964, 29, 1660.
(10) Uso´n, R.; Fornie´s, J. AdV. Organomet. Chem. 1988, 28, 188.
Crystallographic Analysis of 1. Colorless crystals were grown by
slow diffusion of n-hexane into a solution of 1 in chloroform at -30
°C. A representative crystal was selected and mounted on a Siemens/

η2-Phenyl-Metal Interactions
Inorganic Chemistry, Vol. 38, No. 7, 1999 1531
Table 1. Crystallographic Data for
[NBu4][(C6F5)3Pt{µ-Ph2PCH2PPh(η2-Ph)}Pt(C6F5)2] (1) and
[NBu4][(C6F5)3Pt(µ-dppm)(C6F5)2(CO)]‚0.65CHCl3 (5)
1
5
chem formula
fw
C71H58F25N1P2Pt2
1852.3
25(1)
0.71073
Fdd2
C72.65H58.65Cl1.95F25N1O1P2Pt2
1958.0
0(1)
0.71073
Pn
temp (°C)
wavelength (Å)
space group
unit cell dimens
a (Å)
26.520(7)
83.69(3)
13.835(5)
90
90
90
12.259(2)
16.375(3)
18.851(4)
90
100.99(3)
90
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
volume (Å3)
Z
30705(17)
16
3714.8(12)
2
Figure 1. Perspective drawing of the [(C6F5)3Pt2(µ-dppm)Pt(C6F5)2]-
anion.
density (calcd)
(Mg/m3)
abs coeff (µ)
1.603
1.788
3.816
4.020
(mm-1
)
Each chlorine atom was disordered over two positions with partial
occupancies of 0.50 and 0.15. Minor restraints were applied to the C-Cl
distance and Cl-C-Cl angles. The hydrogen atoms of the NBu4 cation
and solvent molecule were omitted from the model.
R indices
R ) 0.0876,
wR ) 0.2074
R ) 0.1726,
wR ) 0.2952
R ) 0.0338,
wR ) 0.0906
R ) 0.0544,
wR ) 0.1042
[I > 2σ(I)]a
final R indices
(all data)
a R ) ∑(|Fo| - |Fc|)/∑|Fo|; wR ) [∑w(|Fo| - |Fc|)2/∑w|Fo| ]1/2
.
The data-to-parameter ratio in the final refinement was 5.5:1. The
2
Goodness-of-fit ) [∑w(|Fo| - |Fc|)2/(Nobs - Nparam)]1/2; w ) 1/σ2(F) +
2
structure was refined on Fo , and all reflections were used in the least-
0.001051F2.
squares calculations.
Programs and computers used and sources of scattering factors are
given in refs 12 and 13.
STOE AED2 4-circle diffractometer. The basic crystallographic
parameters for this complex are listed in Table 1. Data were collected
at 298 K by the ω scan technique. Three standard reflections were
measured after every 45 min of beam exposure during data collection,
showing slow crystal decomposition. For this reason, a ψ scan
correction was not applied. The structure was solved by Patterson and
Fourier methods and refined by full-matrix least-squares. All non-
hydrogen atoms of the anion were assigned anisotropic displacement
parameters The hydrogen atoms of the dppm ligand were omitted from
the model. The NBu4 cation is disordered over two positions with partial
occupancies of 0.5. During refinement it was necessary to apply
geometrical constraints to the C-C and C-N distances. All non-
hydrogen atoms of the cation were assigned a common isotropic
displacement parameter, and the hydrogen atoms were omitted from
the model.
Results and Discussion
As anticipated, the mononuclear complex [NBu4][Pt(C6F5)3-
(dppm-κ1P)] reacts with cis-[M(C6X5)2(thf)2] [M ) Pd, Pt and
X ) Cl, F] in CH2Cl2, yielding the corresponding dinuclear
compounds of general formula [NBu4][(C6F5)3Pt(µ-Ph2PCH2-
PPh2)M(C6X5)2]. Thus the reactions result in the displacement
of the two thf molecules and formation of 1:1 adducts (eq 1).
[NBu4][Pt(C6F5)3(dppm-κ1P)] + cis-[M(C6X5)2(thf)2] f
[NBu4][(C6F5)3Pt(µ-Ph2PCH2PPh2)M(C6X5)2] + 2thf (1)
A difference map following the final refinement shows only three
peaks with electronic density higher than 1 e Å-3, which are located
near the platinum atoms. The value of R (0.0876) is probably due not
only to the partial decomposition of the crystal during data collection
but also to problems arising from having a very long crystallographic
axis [b ) 83.69(3) Å].
M ) Pd, Pt and X ) Cl, F
These reactions take place in good yields under mild
conditions. To establish unequivocally the structure of these
binuclear compounds, a crystallographic study of complex 1
was undertaken.
The data-to-parameter ratio in the final refinement was 4.5:1. The
2
structure was refined on Fo , and all reflections were used in the least-
Molecular Structure of [NBu4][(C6F5)3Pt{µ-Ph2PCH2PPh-
(η2-Ph)}Pt(C6F5)2] (1). The structure of the complex anion is
shown in Figure 1. Selected geometrical parameters are given
in Table 2. The core of the anion contains two platinum centers
which are 5.599 Å apart and bridged by the dppm ligand acting
as a 6e- donor (2e- to Pt1, 4e- to Pt2) with one of the phenyl
rings on P1 acting as a η2-donor ligand. The platinum centers
complete their coordination environments with three and two
C6F5 groups, respectively. The Pt-C bond distances for the C6F5
groups range from 2.03(4) to 2.10(4) Å, while the Pt-C bond
distances for the η2-phenyl interaction are longer [Pt(2)-C(50)
) 2.42(3) and Pt(2)-C(51) ) 2.39(3) Å] and similar to the
squares calculations.
Crystallographic Analysis of 5‚0.65CHCl3. A batch of colorless
crystals of 5‚0.65CHCl3 was grown by slow diffusion of n-hexane into
a solution of 5 in chloroform at low temperature (-30 °C). A
representative crystal was selected and mounted on an Enraf-Nonius
CAD4 diffractometer fitted with a ULT1 low-temperature device (N2
stream). The basic crystallographic parameters for this complex are
listed in Table 1. Data were collected at 273 K. The structure was solved
by Patterson and Fourier methods and refined by full-matrix least-
squares. After isotropic convergence an empirical absorption correction11
was applied. All non-hydrogen atoms were assigned anisotropic
displacement parameters. Aromatic hydrogen atoms were constrained
to idealized geometries, and the isotropic displacement parameter of
each of the hydrogen atoms was set to a value of 1.2 times the
equivalent isotropic displacement parameter of its parent carbon atom.
Seven atomic sites in an interstitial zone were modeled as two partially
occupied disordered CHCl3 molecules, sharing a common carbon atom.
(12) The X-ray diffraction data were processed on a Local Area VAX
cluster (VMS V5.5-2) with the commercial package SHELXTL-PLUS
Release 4.21/V, Siemens Analytical X-ray Instruments, Inc.: Madison,
WI, 1990.
(13) Sheldrick, G. M. SHELXL-93: FORTRAN-77 Program for the
Refinement of Crystal Structures from Diffraction Data; University
of Go¨ttingen, 1993.
(11) DIFABS: Walker, N. G.; Stuart, D. Acta Cystallogr., Sect. A 1983,
39, 158.

1532 Inorganic Chemistry, Vol. 38, No. 7, 1999
Casas et al.
Table 2. Selected Bond Distances (Å) and Angles for the Complex
[NBu4][Pt2(C6F5)5(µ-dppm)] (1)
makes the hydrogen atoms of this phenyl group nonequivalents
at that temperature. Moreover three sets of three related signals
with integrating ratios 2H:2H:1H are also observed, each set
being due to one of the noninteracting phenyl rings (see
Experimental Section Ph-b, Ph-c, Ph-d).The signals assigned
to the ortho-hydrogens appear either as doublets of doublets or
Pt(1)-C(1)
Pt(1)-C(7)
Pt(2)-C(19)
Pt(2)-C(50)
Pt(2)-P(2)
P(2)-C(31)
C(50)-C(55)
C(52)-C(53)
C(54)-C(55)
2.10(4)
2.06(4)
2.03(4)
2.42(3)
2.273(9)
1.83(3)
1.39(5)
1.39(5)
1.44(5)
Pt(1)-C(13)
Pt(1)-P(1)
2.07(4)
2.269(9)
2.05(3)
2.39(3)
1.87(3)
1.47(5)
1.38(5)
1.41(6)
Pt(2)-C(25)
Pt(2)-C(51)
P(1)-C(31)
C(50)-C(51)
C(51)-C(52)
C(53)-C(54)
3
as pseudotriplets because in all cases the JP-o-H values are
3
similar to the corresponding Jm-H-o-H. This latter point has
been confirmed by 1H{31P} NMR experiments at -40 °C. The
2-H atom shows neither 195Pt-satellites nor a significant upfield
shift, as would be expected15 for an η2 coordination; however
C(7)-Pt(1)-C(1)
C(1)-Pt(1)-P(1)
C(19)-Pt(2)-C(25)
C(50)-Pt(2)-P(2)
C(55)-C(50)-C(51) 120(3)
C(51)-C(52)-C(53) 123(4)
C(53)-C(54)-C(55) 123(4)
P(1)-C(31)-P(2)
C(19)-Pt(2)-C(50)
83(2)
C(7)-Pt(1)-C(13)
90(2)
1
the presence of five resonances in the H NMR spectrum of 1
94.9(12) C(13)-Pt(1)-P(1)
91.7(11)
89.8(10)
87.2(8)
at -40 °C due to the hydrogen atoms of the phenyl group η2-
coordinated to platinum confirms that this type of interaction
is mantained in solution at that temperature.
86.6(14) C(25)-Pt(2)-P(2)
86.9(8)
C(51)-Pt(2)-P(2)
C(50)-C(51)-C(52) 119(3)
C(52)-C(53)-C(54) 117(4)
C(54)-C(55)-C(50) 117(4)
Complexes containing η2-arene-metal interactions are of
current interest, because they have been proposed as intermediate
species in the transition-metal-catalyzed hydrogenation of
arenes16 and in inter-17,18 as well as in intramolecular18,19
oxidative-addition processes of C(sp2)-E bonds (E ) H or F)
to metal centers. The strength of the η2-arene-metal interaction
depends on the nature of both the arene and the complex
fragment. However, this kind of interaction is usually weak and
can easily be broken by reaction with other ligands.20 A notable
116(2)
96.1(14)
C(19)-Pt(2)-C(51)
97.0(13)
shortest distances found in other η2-aryl-platinum interactions.14
The Pt-P bond distances [Pt(1)-P(1) ) 2.269(9) and Pt(2)-
P(2) ) 2.273(9) Å] are equal within experimental error.
The bond angles around each platinum center range from 83-
(2)° to 94.9(12)° for cis ligands and from 173(2)° to 178(1)°
for trans ligands. The coordination planes of the platinum atoms
form an angle of 7.0°. The P(1)-C(31)-P(2) angle is 116(2)°,
and the phosphorus atoms are in slightly distorted tetrahedral
environments. The C(50)-C(51) distance [1.47(5) Å] is similar
to distances found in other platinum complexes containing η2-
aryl interactions.14 The C-C distances of the phenyl ring
involved in the η2-phenyl interaction are equal within experi-
mental error; that is, the aromaticity of the ring is maintained
and this fact indicates that the η2-phenyl interaction is very weak,
as its subsequent reactivity confirms.
2+
exception to this general trend concerns the Os(NH3)5
fragment, which binds arenes so strongly that it behaves as a
protecting group for the CdC double bond attached to it.21
The presence of η2-arene-metal coordination has been
(15) Tagge, C. D.; Bergman, R. G. J. Am. Chem. Soc. 1996, 118, 6908.
(16) (a) Parshall, G. W.; Ittel, S. D. Homogeneous Catalysis, 2nd ed.;
Wiley: New York, 1992; Chapter 7, pp 180-183. (b) Muetterties, E.
L.; Bleeke, J. R. Acc. Chem. Res. 1979, 12, 324. (c) Gastinger, R. G.;
Klabunde, K. J. Transition Met. Chem. 1979, 4, 1.
(17) (a) Perthuisot, C.; Jones, W. D. J. Am. Chem. Soc. 1994, 116, 3647.
(b) Belt, S. T.; Helliwell, M.; Jones, W. D.; Partridge, M. G.; Perutz,
R. N. J. Am. Chem. Soc. 1993, 115, 1429. (c) Jones, W. D.; Hessell,
E. T. J. Am. Chem. Soc. 1992, 114, 6087. (d) Jones, W. D.; Partridge,
M. G.; Perutz, R. N. J. Chem. Soc., Chem. Comm. 1991, 264. (e)
Belt, S. T.; Duckett, S. B.; Haddleton, D. M.; Perutz, R. N.
Organometallics 1989, 8, 748. (f) Faller, J. W.; Smart, C. J.
Organometallics 1989, 8, 602. (g) Belt, S. T.; Duckett, S. B.; Helliwell,
M.; Perutz, R. N. J. Chem. Soc., Chem. Commun. 1989, 928. (h) Green,
M. L. H.; Joyner, D. S.; Wallis, J. M. J. Chem. Soc., Dalton Trans.
1987, 2823. (i) Sweet, J. R.; Graham, W. A. G. Organometallics 1983,
2, 135. (j) Parshall, G. W. Acc. Chem. Res. 1975, 8, 113. (k) Klabunde,
U.; Parshall, G. W. J. Am. Chem. Soc. 1972, 94, 9081. (l) Parshall, G.
W.; Knoth W. H.; Schunn, R. A. J. Am. Chem. Soc. 1969, 91, 4990.
(m) Chatt, J.; Davidson, J. M. J. Chem. Soc. 1965, 843. (n) Selmeczy,
A. D.; Jones, W. D.; Partridge, M. G.; Perutz, R. N. Organometallics
1994, 13, 522. (o) Chin, R. M.; Dong, L.; Duckett, S. B.; Partridge,
M. G.; Jones, W. D.; Perutz, R. N. J. Am. Chem. Soc. 1993, 115,
7685. (p) Belt, S. T.; Dong, L.; Duckett, S. B.; Jones, W. D.; Partridge,
M. G.; Perutz, R. N. J. Chem. Soc., Chem. Commun. 1991, 266. (q)
Jones, W. D.; Feher, F. J. Acc. Chem. Res. 1989, 22, 91. (r) Jones, W.
D.; Feher, F. J. J. Am. Chem. Soc. 1986, 108, 4814. (s) Jones, W. D.;
Feher, F. J. J. Am. Chem. Soc. 1984, 106, 1650.
NMR spectroscopic data are in agreement with the solid-
state structure. The 31P NMR spectra (see Experimental Section)
of the products show two signals for the two phosphorus atoms
of the dppm ligand. One of these displays platinum satellites
with a value of 1JPt-P similar to that found in [NBu4][Pt(C6F5)3-
(dppm-κ1P)] (1JPt-P: 2617 Hz), and hence we assigne it to the
P atom bound to the Pt(C6F5)3 fragment. The other signal,
assigned to the other P atom, appears at different chemical shifts
than in the starting material and, as expected, displays platinum
satellites only in the Pt/Pt complexes (see Experimental Section),
indicating the bridging behavior of the dppm. The room-
1
temperature H NMR spectra of 1-4 in CDCl3 show a broad
signal for the 20 aromatic protons and one multiplet for the
two methylene protons, indicating a fluxional behavior of the
phenyl rings at room temperature. Low-temperature measure-
ments on complex 1 in CD2Cl2 on a 300 MHz spectrometer
between -100 and -20 °C show two multiplets for the two
methylene protons at 3.31 and 3.50 ppm and several signals in
the range between 6 and 10 ppm, some of which were severely
overlapped. To obtain a better separation between signals and
allow their assignment, the 1H NMR spectrum and the 1H-1H
COSY at -40 °C were registered on a 500 MHz spectrometer.
From these experiments five signals, each one corresponding
to one proton, are identified as belonging to the phenyl group
bonded to platinum (labeled -Ph-a in the Experimental Section),
in agreement with a static η2-phenyl-platinum interaction which
(18) Jones, W. D.; Feher, F. J. J. Am. Chem. Soc. 1985, 107, 620.
(19) (a) Liu, C.-H.; Li, C.-S.; Cheng, C.-H. Organometallics 1994, 13, 18.
(b) Markies, B. A.; Wijkens, P.; Kooijman, H.; Spek, A. L.; Boersma,
J.; van Koten, G. J. Chem. Soc., Chem. Commun. 1992, 1420. (c) Li,
C.-S.; Cheng, C.-H.; Liao, F.-L.; Wang, S.-L. J. Chem. Soc., Chem.
Commun. 1991, 710. (d) Griffiths, D. C.; Young, G. B. Organome-
tallics 1989, 8, 875.
(20) Shiu, K.-B.; Chou, C.-C.; Wang, S.-L.; Wei, S.-C. Organometallics
1990, 9, 286.
(21) (a) Kopach, M. E.; Harman, W. D. J. Am. Chem. Soc. 1994, 116,
6581. (b) Gonza´lez, J.; Sabat, M.; Harman, W. D. J. Am. Chem. Soc.
1993, 115, 8857. (c) Kopach, M. E.; Kelsh, L. P.; Stork, K. C.;
Harman, W. D. J. Am. Chem. Soc. 1993, 115, 5322. (d) Kopach, M.
E.; Gonza´lez, J.; Harman, W. D. J. Am. Chem. Soc. 1991, 113, 8972.
(e) Harman, W. D.; Hasegawa, T.; Taube, H. Inorg. Chem. 1991, 30,
453. (f) Harman, W. D.; Schaefer, W. P.; Taube, H. J. Am. Chem.
Soc. 1990, 112, 2682. (g) Harman, W. D.; Taube, H. J. Am. Chem.
Soc. 1988, 110, 7906.
(14) (a) Casas, J. M.; Fornie´s, J.; Mart´ın, A.; Menjo´n, B. Organometallics
1993, 12, 4376. (b) Fornie´s, J.; Menjo´n, B.; Gome´z, N.; Toma´s, M.
Organometallics 1992, 11, 1187. (c) Belt, S. T.; Duckett, S. B.;
Helliwell, M.; Perutz, R. N. J. Chem. Soc., Chem. Commun. 1989,
928.

η2-Phenyl-Metal Interactions
Inorganic Chemistry, Vol. 38, No. 7, 1999 1533
Table 3. Selected Bond Distances (Å) and Angles for the Complex
[NBu4][Pt2(C6F5)5(µ-dppm)(CO)]‚0.65CHCl3 (5)
Pt(1)-C(2)
Pt(1)-C(8)
Pt(2)-C(1)
Pt(2)-C(26)
P(1)-C(56)
O(1)-C(1)
2.06(2)
2.07(2)
1.90(2)
2.09(2)
1.82(2)
1.14(2)
Pt(1)-C(14)
Pt(1)-P(1)
Pt(2)-C(20)
Pt(2)-P(2)
P(2)-C(56)
2.06(2)
2.279(4)
2.05(2)
2.326(4)
1.83(2)
C(2)-Pt(1)-C(14)
C(14)-Pt(1)-P(1)
C(1)-Pt(2)-C(26)
C(1)-Pt(2)-P(2)
P(1)-C(56)-P(2)
89.5(7)
91.2(5)
90.5(8)
94.7(6)
130.3(10)
C(2)-Pt(1)-C(8)
C(8)-Pt(1)-P(1)
C(20)-Pt(2)-C(26)
C(20)-Pt(2)-P(2)
85.5(7)
93.8(5)
85.7(6)
89.2(5)
proposed prior to intramolecular C-H activation in the synthesis
of cyclometalated complexes by metalation of arene rings of
coordinated ligands. Jones and Feher inferred the existence of
a η2-arene intermediate in the C-H activation of [(C5-
Me5)Rh(PMe2CH2C6H5)], producing the aryl-hydride derivative
[(C5Me5)Rh(PMe2CH2C6H4)H],17 but the η2-aryl-Rh complex
could not be observed. Complex 1 shows an intramolecular η2-
phenyl-Pt interaction which can be regarded as the intermediate
derivative in a intramolecular C-H activation process. However,
the anticipated subsequent step of oxidative addition to afford
the phenyl-hydride-Pt complex does not take place, and
complex 1 is recovered unaltered after heating to reflux in
toluene for half an hour. The study of the thermal stability of 1
by TGA (to check the possibility of an intramolecular C-H
activation at higher temperatures) shows the expected weight
loss corresponding to HC6F5 (the logical product of the reductive
elimination) at temperatures very close to the decomposition
temperature.
Figure 2. Perspective drawing of the [(C6F5)3Pt2(µ-dppm)Pt(C6F5)2-
(CO)]- anion.
Scheme 1
The weak character of the η2-phenyl-Pt interaction suggests
that these compounds are suitable precursors into which other
ligands could be introduced, affording products which are also
dinuclear. Thus dichloromethane solutions of 1 and 2 react,
respectively, with monodentate ligands such as CO, PPh3, and
p-toluidine displacing the η2-phenyl-metal interaction and
yielding dinuclear compounds of general formula [NBu4]-
[(C6F5)3Pt(µ-dppm)M(C6F5)2L] [M ) Pt, L ) CO 5, PPh3 6;
M ) Pd, L ) p-tol 7] (eq 2).
anion appears as Figure 2.
Compound 5 is a homodinuclear species which contains two
different platinum fragments [“Pt(C6F5)2(CO)” and “Pt(C6F5)3”]
linked, through the platinum centers, by the P atoms of the
bridging dppm ligand. Each platinum center is in a distorted
square-planar environment, and the dihedral angle formed by
the two coordination planes is 112.3°. The bond angles around
each platinum center range from 85.5(7)° to 94.7(6)° for cis
ligands and from 172.5(5)° to 179.0(5)° for trans ligands. The
Pt-P bond distances [Pt(1)-P(1) ) 2.279(4), Pt(2)-P(2) )
2.326(4) Å] are similar to distances found in other platinum
complexes containing P-donor ligands.14 The P(1)-C(56)-P(2)
angle [130.3(10)°] is larger than that expected for sp3 hybridiza-
tion at the carbon atom, this value being the largest found for
similar species containing the dppm ligand acting as a bridge
between two metal centers.22
[NBu4][(C6F5)3Pt{µ-Ph2PCH2PPh(η2-Ph)}M(C6F5)2] +
L f [NBu4][(C6F5)3Pt(µ-dppm)M(C6F5)2L] (2)
M ) Pt and L ) CO, PPh3
M ) Pd and L ) p-tol
The C-O distance [1.14(2) Å] is similar to that found in
other complexes containing CO terminal ligands.23 The absence
of the η2-phenyl interaction in 5 makes the dppm ligand more
flexible and allows a longer Pt(1)-Pt(2) distance (6.373 Å) than
in 1.
The new compounds have been characterized by elemental
analyses and spectroscopic means (IR and NMR). The IR spectra
show the typical absorption for the CO [ν(CO) ) 2109 cm-1],
PPh3, and p-toluidine [ν(NH) ) 3348 cm-1] ligands. The 31P
NMR spectra show for complex 5 two signals for the two P
atoms of the dppm ligand with platinum satellites [1J(195Pt,P)
) 2611 and 2194 Hz]; for complex 6 three signals, two for the
P atoms of the dppm and the other for the P atom of the PPh3,
all of them with platinum satellites [1J(195Pt,P) ) 2642, 2430,
and 2317 Hz]; for complex 7 two signal for the phosphorus
atoms of the dppm ligand but as expected only one with
platinum satellites [1J(195Pt,P) ) 2595 Hz].
In addition, the solid-state structure of 5 has been established
by X-ray diffraction.
Crystal Structure of [NBu4][(C6F5)3Pt(µ-dppm)Pt(C6F5)2-
(CO)] (5). Selected geometrical parameters are given in Table
3. A thermal ellipsoid drawing of the structure of the complex
Conclusions
The reactions of [NBu4][Pt(C6F5)3(dppm-κ1P)] and cis-
[M(C6X5)2(thf)2] (M ) Pt, Pd; X ) F, Cl) proceed through the
displacement of both thf groups and formation of the corre-
sponding dinuclear complexes; see Scheme 1. The dppm ligand
acts as a six-electron donor ligand with one of the phenyl groups
(22) Data were retrieved from the Cambridge Structural Database. Allen,
F. H.; Kennard, O. Chem. Des. Automation News 1993, 8, 1 and 31.
(23) Orpen, A. G.; Brammer, L.; Allen, F. H.; Kennard, O.; Watson, D.
G.; Taylor, R. J. Chem. Soc., Dalton Trans. 1989, S1.

1534 Inorganic Chemistry, Vol. 38, No. 7, 1999
Casas et al.
η2-coordinated to one of the platinum centers. Obviously in such
a situation the resulting compound is a 32-electron complex
and no PtfM bond is required. Since no steric hindrance seems
to be the reason for the absence of a PtfM bond in complex 1
(this would only require both platinum coordination planes to
be perpendicular), the formation of the η2-Pt-phenyl bond
instead of the PtfPt bond has to be due to electronic
preferences.
the Bruker DMX-500, and the Comisio´n Interministerial de
Ciencia y Tecnolog´ıa (Spain) for financial support (Project
PB95-003-CO-1) and for a grant (to A.J.R.).
Supporting Information Available: Tables of crystallographic data
and refinement parameters, atomic coordinates, full lists of bond
distances and angles, anisotropic displacement parameters, and H atom
coordinates for complexes [NBu4][(C6F5)3Pt{µ-Ph2PCH2PPh(η2-Ph)}-
Pt(C6F5)2] and [NBu4][(C6F5)3Pt(µ-dppm)Pt(C6F5)2(CO)]‚0.65CHCl3.
This material is available free of charge via the Internet at http://
pubs.acs.org.
Acknowledgment. We thank Dr. Babil Menjo´n for helpful
discussions, the Unitat de RMN D’Alt Camp (Universitat de
Barcelona) for the measurement of NMR spectra at -40 °C in
IC9808753