Synthesis and structures of palladium and platinum a-frame complexes bridged by a novel binucleating ligand, N,N′-bis[(2-diphenylphosphino)phenyl]-formamidine

Article abstract of DOI:10.1021/om020003f

A novel binucleating ligand, N,N′-bis[(2-diphenylphosphino)phenyl]formamidine (Hdpfam), has been prepared and utilized for the synthesis of homo- and heterobimetallic palladium/platinum complexes M₂R₂(μ-X)(μdpfam) (M = Pd, Pt; R = Me

Full text of DOI:10.1021/om020003f

Organometallics 2002, 21, 2521-2528
2521
Syn th esis a n d Str u ctu r es of P a lla d iu m a n d P la tin u m
A-F r a m e Com p lexes Br id ged by a Novel Bin u clea tin g
Liga n d , N,N′-Bis[(2-d ip h en ylp h osp h in o)p h en yl]-
for m a m id in e
Naofumi Tsukada,* Osamu Tamura, and Yoshio Inoue
Department of Materials Chemistry, Graduate School of Engineering, Tohoku University,
Sendai 980-8579, J apan
Received J anuary 2, 2002
A novel binucleating ligand, N,N′-bis[(2-diphenylphosphino)phenyl]formamidine (Hdpfam),
has been prepared and utilized for the synthesis of homo- and heterobimetallic palladium/
platinum complexes M2R2(µ-X)(µ-dpfam) (M ) Pd, Pt; R ) Me, p-Tol, Cl; X ) Cl, Br, I; dpfam
) N,N′-bis[(2-diphenylphosphino)phenyl]formamidinate). Treatment of Hdpfam with 2 equiv
of MRX(tmeda) or MRX(cod) in the presence of tmeda produced the homobimetallic
complexes. The heterobimetallic complex PdPtMe2(µ-Cl)(µ-dpfam) was obtained by the
reaction of PdMeCl(cod) with PtMe(dpfam), which was produced from PtMe2(cod) and
Hdpfam. The crystal structures of Pd2Cl2(µ-Cl)(µ-dpfam) and Pt2Me2(µ-Cl)(µ-dpfam) have
been determined by X-ray analysis. The results indicate that both complexes have P-M-
Cl-M-P A-frame structures, in which each metal center has a slightly distorted square-
planar geometry and the nonbridging σ-donor ligands (Cl or Me) and µ-Cl are in a cis
orientation. Treatment of Pt2Me2(µ-Cl)(µ-dpfam) with NaBH4 gave the hydride-bridged
complex Pt2Me2(µ-H)(µ-dpfam).
In tr od u ction
diplatinum complexes have received considerable atten-
tion.3-5 However, the application of such complexes as
catalysts is extremely rare.6 We think the geometry of
the bimetallic complexes may be responsible for this lack
of catalytic activity. In several important reactions on
a metal center, the existence of two ligands or vacant
sites in a cis orientation is essential. Although dipalla-
dium and diplatinum complexes are known to adopt
several geometries,2 other ligand molecules (Y) attach
to metal centers in a trans orientation in all geometries,
as illustrated in Chart 1. In contrast, binucleating
tetradentate ligands have a natural preference for the
cis arrangement of Y (Chart 1). Although there are only
a few reports regarding the synthesis of this type of
bimetallic complex,7 such complexes have proven high
Recently, catalysis using bimetallic complexes has
attracted considerable interest.1 Two metal centers in
close proximity have the potential to have a cooperative
effect, both improving the efficiency and selectivity of
catalyzation and promoting reactions that are not
possible using a single metal center. The chemistry of
bimetallic metal complexes containing bridging ligands,
such as bis(diphenylphosphino)methane (dppm) and
(diphenylphosphino)pyridine, has developed remarkably
over the last 30 years.2 In particular, dipalladium and
(1) (a) Rowlands, G. J . Tetrahedron 2001, 57, 1865. (b) van den
Beuken, E. K.; Feringa, B. L. Tetrahedron Lett. 1998, 54, 12985. (c)
Steinhagen, H.; Helmchen, G. Angew. Chem., Int. Ed. Engl. 1996, 35,
2339. (d) Bullock, R. M.; Casey, C. P. Acc. Chem. Res. 1987, 20, 167.
(2) (a) Chaudret, B.; Delavaux, B.; Poilblanc, R. Coord. Chem. Rev.
1988, 86, 191. (b) Puddephatt, R. J .; Manojlovic-Muir, L.; Muir, K. W.
Polyhedron 1990, 9, 2767. (c) Anderson, G. K. Adv. Organomet. Chem.
1993, 35, 1. (d) Puddephatt, R. J . Chem. Soc. Rev. 1983, 12, 99. (e)
Balch, A. L. In Homogeneous Catalysis with Metal Phosphine Com-
plexes; Pignolet, L. H., Ed.; Plenum Press: New York, 1983; p 167.
(3) Recent examples for palladium complexes: (a) Stockland, R. A.,
J r.; Anderson, G. K.; Rath, N. P. Inorg. Chim. Acta 2000, 300-302,
395. (b) Stockland, R. A., J r.; Anderson, G. K.; Rath, N. P. J . Am. Chem.
Soc. 1999, 121, 7945. (c) Stockland, R. A., J r.; Anderson, G. K.; Rath,
N. P. Organometallics 1997, 16, 5096. (d) Stockland, R. A., J r.;
Anderson, G. K.; Rath, N. P. Inorg. Chim. Acta 1997, 259, 173. (e)
Besenyei, G.; Pa´rka´nyi, L.; Foch, I.; Sima´ndi, L. I.; Ka´lma´n, A. Chem.
Commun. 1997, 1143. (f) Besenyei, G.; Pa´rka´nyi, L.; Sima´ndi, L. I.;
J ames, B. R. Inorg. Chem. 1995, 34, 6118. (g) Kluwe, C.; Davies, J . A.
Organometallics 1995, 14, 4257. (h) Davies, J . A.; Kirschbaum, K.;
Kluwe, C. Organometallics 1994, 13, 3664. (i) Dervisi, A.; Edwards,
P. G.; Newman, P. D.; Tooze, R. P.; Coles, S. J .; Hursthouse, M. B. J .
Chem. Soc., Dalton Trans. 1998, 3771. (j) Reid, S. M.; Mague, J . T.;
Fink, M. J . J . Am. Chem. Soc. 2001, 123, 4081. (k) Neve, F.; Longeri,
M.; Ghedini, M.; Crispini, A. Inorg. Chim. Acta 1993, 205, 15. (l)
Rashidi, M.; Vittal, J . J .; Puddephatt, R. J . J . Chem. Soc. 1994, 1283.
(m) Wink, D. J .; Creagan, B. T.; Lee, S. Inorg. Chim. Acta 1991, 180,
183.
(4) Recent examples for platinum complexes: (a) J anka, M.; Ander-
son, G. K.; Rath, N. P. Organometallics 2000, 19, 5071. (b) Irwin, M.
J .; J ia, G.; Vittal, J . J .; Puddephatt, R. J . Organometallics 1996, 15,
5321. (c) Hadj-Bagheri, N.; Puddephatt, R. J . J . Chem. Soc., Dalton
Trans. 1990, 535. (d) Gerisch, M.; Heinemann, F. W.; Bruhn, C.; Scholz,
J .; Steinborn, D. Organometallics 1999, 18, 564. (e) Yam, V. W.-W.;
Chan, L.-P.; Lai, T.-F. Organometallics 1993, 12, 2197. (f) Yam, V. W.-
W.; Yeung, P. K.-Y.; Chan, L.-P.; Kwok, W.-M.; Phillips, D. L.; Yu, K.-
L.; Wong, R. W.-K.; Yan, H.; Meng, Q.-J . Organometallics 1998, 17,
2590. (g) Ghedini, M.; Neve, F. Inorg. Chim. Acta 1990, 178, 5. (h)
Neve, F.; Ghedini, M. Organometallics 1992, 11, 795. (i) Neve, F.;
Ghedini, M.; De Munno, G.; Crispini, A. Inorg. Chem. 1992, 31, 2979.
(j) Toronto, D. V.; Balch, A. L. Inorg. Chem. 1994, 33, 6132. (k)
Yamamoto, Y.; Yamazaki, H. Organometallics 1993, 12, 933.
(5) Recent examples for palladium and platinum heterobimetallic
complexes: (a) Xu, C.; Anderson, G. K. Organometallics 1996, 15, 1760.
(b) Xu, C.; Anderson, G. K. Organometallics 1994, 13, 3981. (c) Fallis,
K. A.; Xu, C.; Anderson, G. K. Organometallics 1993, 12, 2243. For
trimetallic complexes: (d) Tanase, T.; Begam, R. A. Organometallics
2001, 20, 106. (e) Tanase, T.; Takahata, H.; Ukaji, H.; Hasegawa, M.;
Yamamoto, Y. J . Organomet. Chem. 1997, 538, 247. (f) Tanase, T.;
Takahata, H.; Hasegawa, M.; Yamamoto, Y. J . Organomet. Chem.
1997, 545-546, 531.
10.1021/om020003f CCC: $22.00 © 2002 American Chemical Society
Publication on Web 05/16/2002

2522 Organometallics, Vol. 21, No. 12, 2002
Tsukada et al.
Ch a r t 1
cycooctadiene complex PdMeCl(cod) gave the monom-
ethyldipalladium complex 2e as a major product (2e:
2a ) 80:20) (eq 3). The complex 2e may be formed by
efficiency in catalysis. Stanley reported a dirhodium
complex bridged by a tetraphosphine ligand that exhib-
ited higher regioselectivity and reactivity for the hy-
droformylation of R-olefins than the related monome-
tallic complexes.8 Here, we report on the preparation
of a novel binucleating ligand for cis bimetallic com-
plexes and the synthesis of several palladium and
platinum A-frame complexes.
cleavage of the palladium-carbon bond of 2a with HCl.
Since HCl was generated in equimolar amounts with
2a as a byproduct, the monomethyldipalladium species
2e was selectively obtained without the formation of the
trichlorodipalladium complex 2f. Actually, treatment of
2a with a stoichiometric amount of HCl (formed from
acetyl chloride and methanol) in benzene afforded the
complex 2e. Furthermore, the addition of excess amounts
of bases, such as tmeda and diisopropylethylamine,
suppressed the formation of 2e in the reaction of 1 and
PdMeCl(cod) to afford 2a selectively (eq 3). The trichlo-
rodipalladium compound 2f was prepared by the reac-
tion of 1 with 2 equiv of PdCl2(cod) in CH2Cl2 (eq 4). In
Resu lts a n d Discu ssion
Syn th esis of Hom obim eta llic P a lla d iu m a n d
P la tin u m Com p lexes. N,N′-Bis[(2-diphenylphosphi-
no)phenyl]formamidine (1, Hdpfam) was prepared by
heating a mixture of 2-(diphenylphosphino)aniline and
0.5 equiv of trimethyl orthoformate in the presence of
catalytic amounts of TsOH‚H2O (eq 1). Reactions with
a similar manner, the dimethyl- and di-p-tolyldiplati-
num complexes 3a and 3b were also obtained by the
reaction of 1 with PtMeCl(cod) or Pt(p-Tol)Cl(cod) in the
presence of tmeda in acetone (eq 5).
trialkyl orthoacetates or orthobenzoates did not give the
corresponding amidines. Treatment of 1 with 2 equiv
of PdRX(tmeda) (R ) Me, p-Tol; X ) Cl, Br, I; tmeda )
N,N,N′,N′-tetramethylethylenediamine) in acetone at
room temperature resulted in the formation of the
dipalladium complex Pd2R2(µ-X)(µ-dpfam) (2a -d ) (eq 2).
Ch a r a cter iza tion s of A-F r a m e Com p lexes. Crys-
tallization of 2f by vapor diffusion of diethyl ether into
a solution of CH2Cl2 afforded a red crystal suitable for
X-ray analysis. The lattice contains two molecules of
CH2Cl2 per 2f. There are no significant interactions
between 2f and the solvent molecules. The molecular
structure of 2f is shown in Figure 1, and selected bond
distances and angles are presented in Table 1. The
complex 2f adopts a symmetrical A-frame structure with
chlorine at the apex of “A” and two phosphines at the
bottom. The µ-Cl ligand is positioned symmetrically
relative to the metal centers with Pd(1)-Cl(1) ) 2.405-
(4) Å and Pd(2)-Cl(1) ) 2.398 Å, which is longer than
the other Pd-Cl bond (Pd(1)-Cl(2) ) 2.285(5) Å, Pd-
(2)-Cl(3) ) 2.276(5) Å). Each palladium center has a
square-planar geometry with two chloro ligands in a cis
orientation. The N-Pd-P angles (84.0(4), 84.2(4)°) are
However, the reaction of 1 with the corresponding
(6) For example: (a) Sanger, A. R. In Homogeneous Catalysis with
Metal Phosphine Complexes; Pignolet, L. H., Ed.; Plenum Press: New
York, 1983; p 215. (b) Frew, A. A.; Hill, R. H.; Manojlovic´-Muir, L.;
Muir, K. W.; Puddephatt, R. J . J . Chem. Soc., Chem. Commun. 1982,
198. (c) Ishii, H.; Ueda, M.; Takeuchi, K.; Asai, M. J . Mol. Catal. A
1999, 144, 477. (d) Ishii, H.; Goyal, M.; Ueda, M.; Takeuchi, K.; Asai,
M. J . Mol. Catal. A 1999, 148, 289.
(7) (a) Budzelaar, P. H. M.; Frijns, J . H. G.; Orpen, A. G. Organo-
metallics 1990, 9, 1222. (b) Matthews, R. C.; Howell, D. K.; Peng, W.-
J .; Train, S. G.; Treleaven, W. D.; Stanley, G. G. Angew. Chem., Int.
Ed. Engl. 1996, 35, 2253.
(8) (a) Broussard, M. E.; J uma, B.; Train, S. G.; Peng, W.-J .;
Laneman, S. A.; Stanley, G. G. Science 1993, 260, 1784. (b) Laneman,
S. A.; Stanley, G. G. Adv. Chem. Ser. 1992, No. 230, 349.

Pd and Pt A-Frame Complexes
Organometallics, Vol. 21, No. 12, 2002 2523
F igu r e 2. Molecular structure of Pt2Me2(µ-Cl)(µ-dpfam)
(3a ), showing 50% thermal ellipsoids.
F igu r e 1. Molecular structure of Pd2Cl2(µ-Cl)(µ-dpfam)
(2f), showing 50% thermal ellipsoids.
Ta ble 2. Selected Bon d Len gth s (Å) a n d Bon d
An gles (d eg) for 3a
Ta ble 1. Selected Bon d Len gth s (Å) a n d Bon d
An gles (d eg) for 2f
Pt(1)-C1(1)
Pt(1)-P(1)
Pt(2)-Cl(1)
Pt(2)-P(2)
N(1)-C(1)
2.462(8)
2.176(6)
2.444(5)
2.179(5)
1.33(1)
Pt(1)-C(2)
Pt(1)-N(1)
Pt(2)-C(3)
Pt(2)-N(2)
N(2)-C(1)
2.069(10)
2.132(8)
2.07(1)
2.144(8)
1.33(1)
Pd(1)-C1(1)
Pd(1)-P(1)
Pd(2)-Cl(1)
Pd(2)-P(2)
N(1)-C(1)
2.405(4)
2.200(4)
2.398(4)
2.189(4)
1.32(2)
Pd(1)-C1(2)
Pd(1)-N(1)
Pd(2)-Cl(3)
Pd(2)-N(2)
N(2)-C(1)
2.285(5)
2.04(1)
2.276(5)
2.05(1)
1.31(2)
Cl(1)-Pt(1)-C(2)
P(1)-Pt(1)-N(1)
Cl(1)-Pt(1)-P(1)
Pt(1)-N(1)-C(1)
C(1)-N(1)-C(4)
Cl(1)-Pt(2)-C(3)
P(2)-Pt(2)-N(2)
Cl(1)-Pt(2)-P(2)
Pt(2)-N(2)-C(1)
C(1)-N(2)-C(10)
Pt(1)-Cl(1)-Pt(2)
90.2(4)
82.9(3)
P(1)-Pt(1)-C(2)
Cl(1)-Pt(1)-N(1)
94.4(4)
92.7(3)
176.7(3)
114.0(6)
Cl(1)-Pd(1)-Cl(2)
P(1)-Pd(1)-N(1)
Cl(1)-Pd(1)-P(1)
Pd(1)-N(1)-C(1)
C(1)-N(1)-C(2)
Cl(1)-Pd(2)-Cl(3)
P(2)-Pd(2)-N(2)
Cl(1)-Pd(2)-P(2)
Pd(2)-N(2)-C(1)
C(1)-N(2)-C(8)
Pd(1)-Cl(1)-Pd(2)
93.4(2)
84.0(4)
166.0(2)
126.0(10) Pd(1)-N(1)-C(2)
115(1)
93.1(2)
84.2(4)
169.9(2)
127(1)
116(1)
84.8(1)
Cl(2)-Pd(1)-P(1)
Cl(1)-Pd(1)-N(1)
90.1(2)
93.3(4)
168.60(9) N(1)-Pt(1)-C(2)
127.8(6)
116.8(7)
89.2(4)
81.8(3)
Pt(1)-N(1)-C(4)
Cl(2)-Pd(1)-N(1) 172.7(4)
116(1)
P(2)-Pt(2)-C(3)
Cl(1)-Pt(2)-N(2)
94.7(4)
94.1(3)
176.5(4)
Cl(3)-Pd(2)-P(2)
Cl(1)-Pd(2)-N(2)
Cl(3)-Pd(2)-N(2) 172.2(4)
Pd(2)-N(2)-C(8)
N(1)-C(1)-N(2)
88.4(2)
94.6(4)
174.31(9) N(2)-Pt(2)-C(3)
127.6(6)
117.3(7)
80.3(2)
Pt(2)-N(2)-C(10) 113.7(5)
115.2(10)
N(1)-C(1)-N(2) 125.7(8)
130(1)
ligand is positioned symmetrically relative to the metal
centers with Pt(1)-Cl(1) ) 2.462(8) Å and Pt(2)-Cl(1)
) 2.444(5) Å. Each platinum center has a slightly
distorted square-planar geometry (P-Pt-N ) 82.9(3)
and 81.8(3)°).11 The Pt-P bond lengths are short due
to the low trans influence of µ-Cl (Pt(1)-P(1) ) 2.176-
(6)°, Pt(2)-P(2) ) 2.179(5)°). Similar to 2f, the geom-
etries of both nitrogens are almost planar and the
distances between the amidine carbon and the nitrogens
are equal (∑φ(Ν1) ) ∑φ(Ν2) ) 359°; C(1)-N(1) ) C(1)-
N(2) ) 1.33 Å). The Pt-Pt separation of 3.16 Å falls
well outside the range considered typical of Pt-Pt single
bonds.4a-e,g-k,12
The 31P{1H} NMR spectra of the symmetrical dipal-
ladium complexes 2a -d ,f exhibit a single resonance
between 32.00 and 46.38 ppm, that of the methyl
complex 2a appearing at a higher frequency than those
of the aryl complexes 2b-d (Table 3). The P atoms
attached to platinum in 3a ,b give rise to single reso-
slightly acute due to the bidentate PC6H4N units,9 and
both the µ-Cl-Pd-P angles (166.0(2), 169.9(2)°) and the
Cl-Pd-N angles (172.7(4), 172.2(4)°) are distorted. The
geometries of both nitrogens are almost planar, ∑φ(Ν1)
) 357.0° and ∑φ(Ν2) ) 358.2°, and C(1) is positioned
symmetrically relative to the nitrogen atoms (C(1)-N(1)
) 1.32(2) Å, C(1)-N(2) ) 1.31(2) Å), indicating that the
double bond of the amidinate is delocalized. The Pd-
Pd distance is 3.24 Å, indicating that there is no
significant metal-metal interaction.3c,e-h,j-l,10
The structure of the diplatinum complex 3a was also
determined by X-ray analysis. The lattice contains one
molecule of CH2Cl2 per 3a . There are no significant
interactions between 3a and the solvent molecule. The
molecular structure is shown in Figure 2, and selected
bond and angles are presented in Table 2. The complex
3a adopts an A-frame structure similar to 2f. The µ-Cl
(9) (a) Reddy, K. R.; Surekha, K.; Lee, G.-H.; Peng, S.-M.; Chen, J .-
T.; Liu, S.-T. Organometallics 2001, 20, 1292. (b) Ligtenbarg, A. G. J .;
van den Beuken, E. K.; Meetsma, A.; Veldman, N.; Smeets, W. J . J .;
Spek, A. L.; Feringa, B. L. J . Chem. Soc., Dalton Trans. 1998, 263. (c)
Crociani, L.; Bandoli, G.; Dolmella, A.; Basato, M.; Corain, B. Eur. J .
Inorg. Chem. 1998, 1181. (d) Reddy, K. R.; Surakha, K.; Lee, G.-H.;
Peng, S.-M.; Liu, S.-T. Organometallics 2000, 19, 2637.
(10) (a) Davies, J . A.; Pinkerton, A. A.; Syed, R.; Vilmer, M. J . Chem.
Soc., Chem. Commun. 1988, 47. (b) Young, S. J .; Kellenberger, B.;
Reibenspies, J . H.; Himmel, S. E.; Manning, M.; Anderson, O. P.; Stille,
J . K. J . Am. Chem. Soc. 1988, 110, 5744. (c) Besenyei, G.; Lee, C.-L.;
Gulinski, J .; Rettig, S. J .; J ames, B. R.; Nelson, D. A.; Lilga, M. A.
Inorg. Chem. 1987, 26, 3622. (d) Kullberg, M. L.; Kubiak, C. P. Inorg.
Chem. 1986, 25, 26. (e) Khan, M. A.; McAlees, A. J . Inorg. Chim. Acta
1985, 104, 109. (f) Hanson, A. W.; McAlees, A. J .; Taylor, A. J . Chem.
Soc., Perkin Trans. 1985, 441. (g) Kullberg, M. L.; Kubiak, C. P.
Organometallics 1984, 3, 632. (h) Balch, A. L.; Hunt, C. T.; Lee, C.-L.;
Olmstead, M. M.; Farr, J . P. J . Am. Chem. Soc. 1981, 103, 3764. (i)
Bach, A. L.; Benner, L. S.; Olmstead, M. M. Inorg. Chem. 1979, 18,
2996. (j) Olmstead, M. M.; Hope, H.; Benner, L. S.; Balch, A. L. J . Am.
Chem. Soc. 1977, 99, 5502.
(11) Chatterjee, S.; Hockless, D. C. R.; Salem, G.; Waring, P. J .
Chem. Soc., Dalton Trans. 1997, 3889.
(12) (a) Alcock, N. W.; Kemp, T. J .; Pringle, P. G.; Bergamini, P.;
Traverso, O. J . Chem. Soc., Dalton Trans. 1987, 1659. (b) Arsenault,
G. J .; Manojlovic´-Muir, L.; Muir, K. W.; Puddephatt, R. J .; Treurnicht,
I. Angew. Chem., Int. Ed. Engl. 1987, 26, 86. (c) Azam, K. A.; Frew, A.
A.; Lloyd, B. R.; Manojlovic´-Muir, L.; Muir, K. W.; Puddephatt, R. J .
Organometallics 1985, 4, 1400. (d) Frew, A. A.; Hill, R. H.; Manojlovic´-
Muir, L.; Muir, K. W.; Puddephatt, R. J . J . Chem. Soc., Chem.
Commun. 1982, 198. (e) Brown, M. P.; Cooper, S. J .; Frew, A. A.;
Manojlovic´-Muir, L.; Muir, K. W.; Puddephatt, R. J .; Thomson, M. A.
J . Chem. Soc., Dalton Trans. 1982, 299. (f) Fisher, J . R.; Mills, A. J .;
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A. A.; Manojlovic´-Muir, L.; Muir, K. W. Organometallics 1982, 1, 1421.
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K. W.; Puddephatt, R. J .; Seddon, K. R.; Thomson, M. A. Inorg. Chem.
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1984, 549.

2524 Organometallics, Vol. 21, No. 12, 2002
Ta ble 3. 1H a n d 31P {1H} NMR Da ta for Com p lexes 2-6 in CDCl3 Solu tion
Tsukada et al.
complex
δ(P), ppm
1J PtP (Hz)
δ(H) (amidine), ppm
δ(H) (methyl), ppm
J PH (Hz)
2J PtH (Hz)
Pd2Me2(µ-Cl)(µ-dpfam) (2a )
Pd2Tol2(µ-Cl)(µ-dpfam) (2b)
Pd2Tol2(µ-Br)(µ-dpfam) (2c)
Pd2Tol2(µ-I)(µ-dpfam) (2d )
Pd2MeCl(µ-Cl)(µ-dpfam) 2ea
Pd2Cl2(µ-Cl)(µ-dpfam) (2f)a
Pt2Me2(µ-Cl)(µ-dpfam) (3a )
Pt2Tol2(µ-Cl)(µ-dpfam) (3b)
PdMe(dpfam) (4a )
40.67
34.45
33.75
32.00
40.14, 46.33
46.38
18.53
8.25
8.11
8.06
8.00
8.13
8.02
8.79b
8.37b
0.64
2.0
0.69
0.71
1.9
2.3
5154
4966
66
16.65
19.01,c 35.46c
20.54d
35.70d
39.00
7.72
0.37
0.24
6.1, 6.8
6.0
73
PtMe(dpfam) (4b)
2368
3002
7.81b
8.55b
PdPtMe2(µ-Cl)(µ-dpfam) (5)
Pt2Me2(µ-H)(µ-dpfam) (6)
0.66
0.70
0.93
1.7
2.4
e
20.22
31.10
5079
e
e
f
10.13
a
b 3
c 2
d
2
f 1
2
3
In CD2Cl2.
68 Hz.
J
values were unresolved.
J
) 402 Hz. J PP ) 424 Hz. e Unresolved.
J
) 3863 Hz, J PtP ) 391 Hz, J PP
)
PtH
PP
PtP
nances at 18.53 and 16.65 ppm, respectively, with 195Pt
1
satellites. The J PtP values, 5154 Hz for 3a and 4966
Hz for 3b, are larger than those for the corresponding
mononuclear complex PtMeCl[2-aminophenyl(diphe-
nylphosphine)] (4617 Hz),13 indicating the lower trans
influence of µ-Cl compared to nonbridging Cl, consistent
with the short Pt-P bond lengths.14
Syn th esis of Mon om eta llic a n d Heter obim eta llic
P a lla d iu m a n d P la tin u m Com p lexes. Treatment of
1 and 1 equiv of PdMe2(tmeda) or PtMe2(cod) in acetone
at room temperature caused the evolution of methane
and produced the monometallic complexes PdMe(dpfam)
(4a ) and PtMe(dpfam) (4b) (eq 6). The reaction of 1 with
F igu r e 3. Molecular structure of PdMe(dpfam) (4b),
showing 50% thermal ellipsoids.
Ta ble 4. Selected Bon d Len gth s (Å) a n d Bon d
An gles (d eg) for 4b
Pt(1)-C(1)
Pt(1)-P(1)
N(1)-C(2)
2.067(6)
2.257(1)
1.374(6)
Pt(1)-N(1)
Pt(1)-P(2)
N(2)-C(2)
2.126(4)
2.287(1)
1.277(7)
1 equiv of PtMeCl(cod) in the presence of excess tmeda
also afforded 4b, although treatment of 1 with 1 equiv
of PdMeCl(tmeda) resulted in the formation of small
amounts of the bimetallic complex 2a . These monome-
tallic complexes 4a ,b were characterized by 31P{1H} and
1H NMR analysis. The 31P{1H} NMR spectra of 4a
exhibit two sets of doublets at 19.01 and 35.46 ppm (2J PP
) 402 Hz). Similarly, those of 4b exhibit two sets of
doublets with 195Pt satellites at 20.54 (1J PtP ) 2368 Hz)
P(1)-Pt(1)-C(1)
P(2)-Pt(1)-N(1)
N(1)-Pt(1)-C(1)
Pt(1)-N(1)-C(2)
C(2)-N(1)-C(20)
C(2)-N(2)-C(26)
90.6(2)
96.4(1)
171.0(2)
119.6(3)
114.4(4)
123.9(5)
P(1)-Pt(1)-N(1)
P(2)-Pt(1)-C(1)
P(1)-Pt(1)-P(2)
Pt(1)-N(1)-C(20)
N(1)-C(2)-N(2)
82.8(1)
91.1(2)
170.51(5)
117.9(3)
130.4(5)
angle of 170.51(5)°, and a P(1)-Pt(1)-N(1) angle of 82.8-
(1)°. There is no significant difference between the bond
lengths Pt(1)-P(1) and Pt(1)-P(2). While the nitrogen
atom N(1) of the amidinate exists in the ideal position
around the square-planar platinum center, the Pt(1)-
N(2) distance is too long to consider the coordination of
the nitrogen atom N(2) to the platinum center. The bond
lengths N(1)-C(2) of 1.374(6) Å and N(2)-C(2) of 1.277-
(7) Å coincide with typical lengths of sp2 C-N single
bonds and CdN double bonds, respectively, indicating
that the double bond of the amidinate is almost local-
ized, although the torsion angle N(1)-C(2)-N(2)-C(26)
of -10.3(10)° is not consistent with the ideal double
bond.
2
and 35.70 (1J PtP ) 3002 Hz) ppm, with a J PP value of
1
424 Hz. In the H NMR spectra, the methyl group of
4a produces a triplet at 0.24 ppm (3J PH ) 6.0 Hz), and
a double doublet is observed with 195Pt satellites at 0.37
1
ppm (3J PH ) 6.1 and 6.8 Hz, J PtH ) 73 Hz) in the case
of 4b . These results indicate that the two phosphine
atoms coordinate to the metal centers.
The structure of 4b was determined by X-ray analysis.
The molecular structure is shown in Figure 3, and
selected bond distances and angles are presented in
Table 4. The molecule exhibits a slightly distorted
square planar geometry about the platinum with a
N(1)-Pt(1)-C(1) angle of 171.0(2)°, a P(1)-Pt(1)-P(2)
The isolated 4b reacts with 1 equiv of PtMeCl(cod)
in benzene to give the bimetallic platinum complex 3a
(Scheme 1). Similarly, the dipalladium complex 2a is
formed quantitatively by treatment of 4a with 1 equiv
(13) Pfeiffer, J .; Kickelbick, G.; Schubert, U. Organometallics 2000,
19, 62.
(14) Mather, G. G.; Pidcock, A.; Rapsey, G. J . N. J . Chem. Soc.,
Dalton Trans. 1973, 2095.

Pd and Pt A-Frame Complexes
Sch em e 1
Organometallics, Vol. 21, No. 12, 2002 2525
F igu r e 4. Molecular structure of Pt2Me2(µ-H)(µ-dpfam)
(6), showing 50% thermal ellipsoids.
of PdMeCl(cod). The reaction of 4a with PdCl2(cod)
affords the complex 2e in pure form.
Ta ble 5. Selected Bon d Len gth s (Å) a n d Bon d
An gles (d eg) for 6
The synthesis of the palladium and platinum hetero-
bimetallic complex 5 was then investigated. Both the
reaction of 4a with PtMeCl(cod) and the reaction of 4b
with PdMeCl(cod) afford the complex 5 selectively,
without the formation of the homobimetallic complexes
2a and 3a . The 31P{1H} NMR spectra for 5 exhibit two
single resonances at 20.22 ppm (1J PtP ) 5079 Hz) and
39.00 ppm, which are close to those of the corresponding
homobimetallic complexes 3a and 2a (Table 3), respec-
tively. In the 1H NMR spectra, the methyl groups on
the palladium and the platinum also exhibit chemical
shifts and J values similar to those of 3a and 2a . The
chemical shift of the amidine proton of 5 (8.55 ppm) is
between those of 3a and 2a (8.79 and 8.25 ppm).
Syn th esis a n d Str u ctu r e of a Hyd r id e-Br id ged
P la tin u m A-F r a m e Com p lex. The diplatinum com-
plex 3a was converted to the corresponding hydride-
bridged derivative 6 by treatment of NaBH4 in CH2Cl2
and MeOH (eq 7).12e,15 The structure of 6 was deter-
Pt(1)-Pt(2)
Pt(1)-C(2)
Pt(1)-N(1)
Pt(2)-P(2)
N(1)-C(1)
2.8000(6)
2.060(10)
2.116(6)
2.210(2)
1.32(1)
Pt(1)-P(1)
Pt(2)-C(3)
Pt(2)-N(2)
N(2)-C(1)
2.217(2)
2.056(10)
2.138(6)
1.32(1)
Pt(2)-Pt(1)-C(2)
P(1)-Pt(1)-N(1)
Pt(2)-Pt(1)-P(1)
Pt(1)-N(1)-C(1)
C(1)-N(1)-C(4)
Pt(1)-Pt(2)-C(3)
P(2)-Pt(2)-N(2)
Pt(1)-Pt(2)-P(2)
Pt(2)-N(2)-C(1)
C(1)-N(2)-C(10)
N(1)-C(1)-N(2)
99.2(3)
83.2(2)
P(1)-Pt(1)-C(2)
Pt(2)-Pt(1)-N(1)
N(1)-Pt(1)-C(2)
Pt(1)-N(1)-C(4)
94.9(3)
82.7(2)
178.1(4)
115.7(5)
156.34(6)
125.7(5)
118.1(7)
100.3(3)
83.4(2)
156.87(5)
124.0(5)
117.7(6)
122.5(7)
P(2)-Pt(2)-C(3)
Pt(1)-Pt(2)-N(2)
N(2)-Pt(2)-C(3)
Pt(2)-N(2)-C(10)
92.9(3)
83.6(2)
176.2(4)
118.3(5)
by 31P{1H} analysis. The spectrum of 6 exhibits a typical
AA′XX′ spin system together with 195Pt atoms (1J PtP
)
2
3
3863 Hz, J PtP ) 391 Hz, J PP ) 68 Hz), which is very
similar to that previously reported for a linear P-Pt-
Pt-P system.17
In the X-ray analysis, the hydrogen atom H(1) was
found by difference Fourier synthesis to be disordered
between the Pt(1) and Pt(2) atoms. The two hydrogen
atoms H(1) and H(1′), where the occupancies of 0.6 and
0.4 are assigned, are positioned symmetrically relative
to the metal centers (Pt(1)-H(1) ) 1.66(7) Å, Pt(2)-
H(1) ) 1.63(8) Å; Pt(1)-H(1′) ) 1.70(8) Å, Pt(2)-H(1′)
) 1.69(8) Å). These Pt-H lengths are shorter than the
distances previously reported for a hydride-bridged
platinum A-frame complex, as is the case for the Pt-Pt
distances as well.5d Although the hydride H(1) is ar-
ranged in a trans position to the phosphines, the
P-Pt-H angles are not linear (P(1)-Pt(1)-H(1) ) 164-
(2)° and P(2)-Pt(2)-H(1) ) 168(2)°). Considering that
the Pt-Pt-P angles are also bent (Pt(2)-Pt(1)-P(1) )
156.33(6)° and Pt(1)-Pt(2)-P(2) ) 156.85(5)°), these
nonlinearities may be related to a three-center-two-
electron bond in the bridging Pt2(µ-H) unit.12e,15,18 The
presence of a symmetrical bridging hydride in 6 is also
mined by X-ray analysis. The molecular structure is
shown in Figure 4, and selected bond distances and
angles are presented in Table 5. The Pt-Pt length in 6
(2.8000(6) Å) is slightly longer than the Pt-Pt distances
(2.620(1)-2.769(1) Å) in the “side-by-side” binuclear
platinum complexes, in which all structural features are
compatible with the presence of covalent Pt-Pt bond-
ing.12g,16 It is, however, shorter than the Pt-Pt separa-
tion (2.867(2)-2.932(1) Å) in the dppm- and hydride-
bridged platinum A-frame complexes, in which a weak
metal-metal bonding interaction is suggested,5d,12e
indicating the presence of a stronger interaction be-
tween the platinum centers in 6. The shorter distance
can be accounted for by the weaker trans influence of
Ph2P in 6 compared with the alkyl groups in the dppm-
and hydride-bridged complexes12e or the shorter dis-
tance between two nitrogen atoms in the amidinate
compared with two phosphine atoms in dppm. The
interaction between two platinums was also confirmed
(16) (a) Brown, M. P.; Cooper, S. J .; Puddephatt, R. J .; Thomson,
M. A.; Seddon, K. R. J . Chem. Soc., Chem. Commun. 1979, 1117. (b)
Brown, M. P.; Fisher, J . R.; Manojlovic´-Muir, L.; Muir, K. W.;
Puddephatt, R. J .; Thomson, M. A.; Seddon, K. R. J . Chem. Soc., Chem.
Commun. 1979, 931. (c) Few, A. A.; Manojlovic´-Muir, L.; Muir, K. W.
J . Chem. Soc., Chem. Commun. 1980, 624. (d) Manojlovic´-Muir, L.;
Muir, K. W.; Solomum, T. J . Organomet. Chem. 1979, 179, 479. (e)
Manojlovic´-Muir, L.; Muir, K. W.; Solomum, T. Acta Crystallogr., Sect.
B 1979, 35, 1237.
(15) (a) Brown, M. P.; Puddephatt, R. J .; Rashidi, M.; Seddon, K. R.
J . Chem. Soc., Dalton Trans. 1978, 516. (b) Brown, M. P.; Puddephatt,
R. J .; Rashidi, M. Inorg. Chim. Acta 1977, 23, L27.
(17) Ku¨hn, A.; Werner, H. J . Organomet. Chem. 1979, 179, 421.
(18) See also refs 3a,b,d.

2526 Organometallics, Vol. 21, No. 12, 2002
Tsukada et al.
1H NMR (400 MHz, CDCl3): δ 6.80 (m, 2H), 6.95 (m, 2H), 7.22
(m, 2H), 7.24-7.36 (m, 22H), 7.57 (s, 1H, NCHN), 7.65 (br s,
1H, NH). 31P{1H} NMR (162 MHz, CDCl3): δ -19.25, -15.02.
revealed in the 1H NMR spectrum. A resonance at -4.06
ppm, with the appearance of a 1:8:18:8:1 quintet due to
coupling with 195Pt and with each peak further split into
a 1:2:1 triplet due to coupling with 31P, was observed
(1J PtH ) 780 Hz, 2J PH ) 93 Hz). The two hydrogen atoms
H(1) and H(1′) are equivalent in solution because of a
fast flipping of the P-Pt-Pt-P system.
Anal. Calcd for
C37H30N2P2: C, 78.71; H, 5.36; N, 4.96.
Found: C, 78.41; H, 5.46; N, 5.07. Mp: 164-165 °C.
P d 2Me2(µ-Cl)(µ-d p fa m ) (2a ). To a solution of 1 (0.28 g, 0.50
mmol) in acetone (20 mL) was added PdMeCl(tmeda) (0.27 g,
1.0 mmol). The mixture was stirred at room temperature
overnight to give a pale yellow precipitate, which was collected
by filtration after the addition of H2O (20 mL) to the suspen-
sion, washed with H2O, MeOH, and ether and dried. Yield:
0.36 g, 86%. This complex slowly reacted with halogenated
solvents, such as CHCl3 and CH2Cl2, to give 2e,f by cleavage
Su m m a r y
In this study, a series of dpfam- and halide-bridged
palladium and platinum A-frame complexes were syn-
thesized. A palladium and platinum heterobimetallic
complex was also prepared via the monometallic com-
plexes. Treatment of the chloride-bridged platinum
A-frame complex with NaBH4 afforded the hydride-
bridged complex. The tetradentate ligand dpfam permits
flexible metal-metal distances. The Pd-Pd distance in
the chloride-bridged complex 2f is longer than that in
the related dppm- and chloride-bridged palladium com-
plexes (3.24 vs 3.03 Å).10c In contrast, the hydride-
bridged complex 6 exhibits shorter Pt-Pt distances than
dppm- and hydride-bridged complexes (2.8006(9) Å vs
2.867(2)-2.932(1) Å).5d,12e In all of the complexes, the
metal centers have a distorted-square-planar geometry
with two ligands other than dpfam in a cis orientation,
which is expected to exhibit different reactivities than
the well-known dppm-bridged A-frame complexes. Re-
ductive elimination, insertion, and oxidative addition on
the dpfam-bridged A-frame complexes and application
in catalysis are currently under investigation.
1
of the methylpalladium group. H NMR (400 MHz, CDCl3): δ
3
0.64 (d, J (P,H) ) 2.0 Hz, 6H, PdMe), 6.90 (m, 2H), 7.03 (m,
2H), 7.10 (m, 2H), 7.26-7.36 (m, 12H), 7.44 (m, 4H), 7.59 (m,
8H), 8.25 (s, 1H, NCHN). 31P{1H} NMR (162 MHz, CDCl3): δ
40.67. Anal. Calcd for C39H35ClN2P2Pd2: C, 55.63; H, 4.19; N,
3.33; Cl, 4.21. Found: C, 55.69; H, 4.51; N, 3.18; Cl, 4.31. Mp:
>260 °C.
P d 2(p-Tol)2(µ-Cl)(µ-d p fa m ) (2b). This complex was pre-
pared in a manner similar to that above from 1 (56 mg, 0.10
mmol) and Pd(p-Tol)Cl(tmeda) (70 mg, 0.20 mmol) and isolated
1
as a beige powder (86 mg, 86%). H NMR (400 MHz, CDCl3):
δ 2.04 (s, 6H, C6H4Me), 6.47 (d, J ) 8.0 Hz, 4H, C6H4Me-3,5),
6.85 (m, 4H, C6H4Me-2,6), 6.95-7.02 (m, 4H), 7.20-7.35 (m,
14H), 7.41 (m, 4H), 7.48 (m, 8H), 8.11 (s, 1H, NCHN). 31P{1H}
NMR (162 MHz, CDCl3): δ 34.45. Anal. Calcd for C51H43
-
ClN2P2Pd2: C, 61.62; H, 4.36; N, 2.82; Cl, 3.57. Found: C,
61.68; H, 4.56; N, 2.82; Cl, 3.33. Mp: >260 °C.
P d 2(p-Tol)2(µ-Br )(µ-d p fa m ) (2c). This complex was pre-
pared in a manner similar to that for 2a from 1 (56 mg, 0.10
mmol) and Pd(p-Tol)Br(tmeda) (79 mg, 0.20 mmol) and isolated
as a pale yellow powder (74 mg, 71%). 1H NMR (400 MHz,
CDCl3): δ 2.04 (s, 6H, C6H4Me), 6.48 (d, J ) 7.6 Hz, 4H, C6H4-
Me-3,5), 6.87 (m, 4H, C6H4Me-2,6), 6.93-7.01 (m, 4H), 7.20-
7.35 (m, 14H), 7.41 (m, 4H), 7.48 (m, 8H), 8.06 (s, 1H, NCHN).
31P{1H} NMR (162 MHz, CDCl3): δ 33.75. Anal. Calcd for
Exp er im en ta l Section
All reactions were carried out under a nitrogen atmosphere.
The compounds 2-(diphenylphosphino)aniline,19 PdMeCl(t-
meda),20 PdMe2(tmeda),20 PdMeCl(cod),21 Pd(p-Tol)Cl(tmeda),22
Pd(p-Tol)Br(tmeda),22 Pd(p-Tol)I(tmeda),22 PtMeCl(cod),23 PtMe2-
(cod),23 and Pt(p-Tol)Cl(cod)23 were prepared by literature
methods.
NMR spectra were recorded by using a Bruker DPX-400 or
Bruker DRX-500 spectrometer. 1H NMR chemical shifts were
measured relative to tetramethylsilane in CDCl3 or relative
to the residual solvent peak in CD2Cl2. Phosphorus chemical
shifts were determined relative to 85% H3PO4 as an external
standard.
P r ep a r a tion of Hd p fa m (1). A solution of 2-(diphe-
nylphosphino)aniline (5.6 g, 20 mmol), trimethyl orthoformate
(1.1 mL, 10 mmol), and a catalytic amount of p-TsOH‚H2O in
benzene (10 mL) was gently refluxed for 12 h, while distilling
off the methanol generated. After cooling and addition of
saturated NaHCO3 (10 mL), the reaction mixture was ex-
tracted with benzene (2 × 30 mL). The combined extracts were
dried over anhydrous Na2SO4 and evaporated to give a yellow
oil. Diisopropyl ether (20 mL) was added to the oil, and the
mixture was refluxed for 1 h. After the mixture was cooled to
room temperature, white precipitates were collected by filtra-
tion, washed with cold diisopropyl ether, and dried to yield
4.8 g (86%) of the analytically pure product as a white powder.
C
51H043BrN2P2Pd2: C, 58.98; H, 4.17; N, 2.70; Br, 7.69.
Found: C, 59.19; H, 4.35; N, 2.79; Br, 7.63. Mp: >260 °C.
P d 2(p-Tol)2(µ-I)(µ-d p fa m ) (2d ). This complex was pre-
pared in manner similar to that for 2a from 1 (0.28 g, 0.50
mmol) and Pd(p-Tol)I(tmeda) (0.44 g, 1.0 mmol) and isolated
as a pale yellow powder (0.50 g, 92%). 1H NMR (500 MHz,
CDCl3): δ 2.04 (s, 6H, C6H4Me), 6.46 (d, J ) 7.9 Hz, 4H, C6H4-
Me-3,5), 6.88 (m, 4H, C6H4Me-2,6), 6.93 (m, 2H), 6.97 (m, 2H),
7.23-7.33 (m, 14H), 7.40 (m, 4H), 7.47 (m, 8H), 8.00 (s, 1H,
NCHN). 31P{1H} NMR (162 MHz, CDCl3): δ 32.00 Anal. Calcd
for C51H43IN2P2Pd2: C, 56.43; H, 3.99; N, 2.58; I, 11.69.
Found: C, 56.14; H, 4.12; N, 2.91; I, 11.70. Mp: >260 °C.
Rea ction of 1 w ith P d MeCl(cod ). To a solution of 1 (56
mg, 0.10 mmol) in acetone (4 mL) was added PdMeCl(cod) (53
mg, 0.20 mmol). The mixture was stirred at room temperature
overnight to give an orange precipitate, which was collected
by filtration after the addition of H2O (4 mL) to the suspension,
washed with H2O, MeOH, and ether, and dried. The mixture
1
of 2a and 2e (20:80, determined by H NMR) was obtained in
91% yield (78 mg).
Rea ction of 1 w ith P d MeCl(cod ) in th e P r esen ce of
Am in es. To a solution of 1 (56 mg, 0.10 mmol) and tmeda (30
µL, 0.20 mmol) in acetone (4 mL) was added PdMeCl(cod) (53
mg, 0.20 mmol). The mixture was stirred at room temperature
overnight to give a pale yellow precipitate, which was collected
by filtration after H2O (20 mL) was added to the suspension,
washed with H2O, MeOH, and ether, and dried. The complex
2a was obtained as the sole product in 90% yield (76 mg).
Using i-Pr2NEt (70 µL, 0.4 mmol) instead of tmeda, 2a was
obtained in 78% yield (66 mg).
(19) Cooper, M. K.; Downes, J . M.; Duckworth, P. A. Inorg. Synth.
1989, 25, 129-133.
(20) Byers, P. K.; Canty, A. J .; J in, H.; Krius, D.; Markies, B. A.;
Boersma, J .; van Koten, G. Inorg. Chem. 1993, 32, 162-172.
(21) Ru¨lke, R. E.; Ernsting, J . M.; Spek, A. L.; Elsevier, C. J .; van
Leeuwen, P. W. N. M.; Vrieze, K. Inorg. Chem. 1993, 32, 5769-5778.
(22) Alsters, P. L.; Boersma, J .; van Koten, G. Organometallics 1993,
12, 1629-1638.
Rea ction of 2a w ith HCl. To a solution of 2a (0.17 g, 0.2
mmol) in benzene (20 mL) and methanol (1 mL) was added a
solution of acetyl chloride (14 µL, 0.2 mmol) in benzene (1 mL).
(23) Clark, H. C.; Manzer, L. E. J . Organomet. Chem. 1973, 59, 411-
428.

Pd and Pt A-Frame Complexes
Organometallics, Vol. 21, No. 12, 2002 2527
The mixture was stirred at room temperature overnight to give
an orange precipitate. After the mixture was evaporated to
ca. 5 mL, the precipitate was collected by filtration, washed
with ether, and dried. The mixture of 2a , 2e, and 2f (4:90:6,
determined by 1H NMR) was obtained in 95% yield (0.16 g).
P d 2Cl2(µ-Cl)(µ-d p fa m ) (2f). To a solution of 1 (0.28 g, 0.50
mmol) in CH2Cl2 (20 mL) was added PdCl2(cod) (0.29 g, 1.0
mmol). The mixture was stirred at room temperature over-
night. Addition of ether to the reaction mixture led to the
precipitation of a orange powder, which was collected by
filtration, washed with ether, and dried. Yield: 0.44 g, 100%.
1H NMR (500 MHz, CD2Cl2): δ 7.10 (m, 2H), 7.16 (m, 2H),
7.24 (m, 2H), 7.39-7.47 (m, 12 H), 7.57 (m, 4H), 7.75 (m, 8H),
8.02 (s, 1H, NCHN). 31P{1H} NMR (162 MHz, CD2Cl2): δ 46.38.
Anal. Calcd for C37H29Cl3N2P2Pd2: C, 50.34; H, 3.31; N, 3.17;
Cl, 12.05. Found: C, 50.01; H, 3.68; N, 3.21; Cl, 12.49. Mp:
>260 °C.
3H, PdMe), 0.70 (d+br satellites, 3J (P,H) ) 2.4 Hz, 3H, PtMe),
6.87-6.92 (m, 2H), 7.05-7.17 (m, 4H), 7.25-7.34 (m, 10H),
7.39-7.46 (m, 4H), 7.55-7.68 (m, 8H), 8.55 (s+br satellites,
1H, NCHN). 31P{1H} NMR (162 MHz, CDCl3): δ 20.22
(1J (Pt,P) ) 5079 Hz, PtP), 39.00 (PdP). Anal. Calcd for C39H35
-
ClN2P2PdPt: C, 50.33; H, 3.79; N, 3.01; Cl, 3.81. Found: C,
49.92; H, 3.71; N, 3.19; Cl, 3.86. Mp: >260 °C.
Treatment of 4a (69 mg, 0.1 mmol) with PtMeCl(cod) (35
mg, 0.1 mmol) in a similar manner also afforded 5 in 100%
yield (94 mg).
Rea ction of 4a a n d P d Cl2(cod ). To a solution of 4a (77
mg, 0.1 mmol) in benzene (4 mL) was added PdCl2(cod) (29
mg, 0.10 mmol). The mixture was stirred at room temperature
overnight to give a orange precipitate of 2e, which was
collected by filtration, washed with benzene, and dried. Yield:
1
3
76 mg, 88%. H NMR (400 MHz, CD2Cl2): δ 0.69 (d, J (P,H)
) 1.9 Hz, 3H, PdMe), 6.97-7.04 (m, 2H), 7.09-7.20 (m, 3H),
7.20-7.26 (m, 1H), 7.35-7.65 (m, 18H), 7.71-7.78 (m, 4H),
8.13 (s, 1H, NCHN). 31P{1H} NMR (162 MHz, CD2Cl2): δ 40.14,
46.33. Anal. Calcd for C38H32Cl2N2P2Pd2: C, 52.92; H, 3.74;
N, 3.25; Cl; 8.22. Found: C, 52.83; H, 4.09; N, 3.40; Cl, 8.50.
Mp: 212 °C dec.
P t2Me2(µ-Cl)(µ-d p fa m ) (3a ). To a solution of 1 (56 mg, 0.10
mmol) and tmeda (30 µL, 0.20 mmol) in acetone (4 mL) was
added PtMeCl(cod) (71 mg, 0.20 mmol). The mixture was
stirred at room temperature overnight to give a white pre-
cipitate, which was collected by filtration after H2O (20 mL)
was added to the suspension, washed with H2O, MeOH, and
ether, and dried. Yield: 90 mg, 88%. 1H NMR (400 MHz,
CDCl3): δ 0.71 (d, 3J (P,H) ) 2.3 Hz, 2J (Pt,H) ) 66 Hz, 6H,
PtMe), 6.92 (m, 2H), 7.17 (m, 4H), 7.31 (m, 10H), 7.43 (m, 4H),
P t2Me2(µ-H)(µ-d p fa m ) (6). To a solution of 3a (0.31 g, 0.30
mmol) in CH2Cl2 (36 mL) was added NaBH4 (23 mg, 0.60
mmol) and methanol (3.6 mL) at 0 °C. After the mixture was
stirred for 1 h at 0 °C, the solvents were removed under
reduced pressure. The solid residue was extracted with CH2-
Cl2 and passed through a Celite column. The solvent was
removed under reduced pressure to give a pale yellow solid.
3
7.63 (m, 8H), 8.79 (s, J (Pt,H) ) 30 Hz, 1H, NCHN). 31P{1H}
1
NMR (162 MHz, CDCl3): δ 18.53, J (Pt,P) ) 5154 Hz. Anal.
Calcd for C39H35ClN2P2Pt2: C, 45.96; H, 3.46; N, 2.75; Cl, 3.48.
Found: C, 46.25; H, 3.58; N, 2.85; Cl, 3.38. Mp: >260 °C.
P t2(p-Tol)2(µ-Cl)(µ-d p fa m ) (3b). This complex was pre-
pared in a manner similar to that for 3a from 1 (56 mg, 0.10
mmol), tmeda (30 µL, 0.20 mmol), and Pt(p-Tol)Cl(tmeda) (86
mg, 0.20 mmol) and isolated as a white powder (0.10 g, 89%).
1H NMR (400 MHz, CDCl3) δ 2.04 (s, 6H, C6H4Me), 6.41 (m,
4H, C6H4Me-3,5), 6.87 (d+br satellites, 3J (H,H) ) 7.9 Hz, 4H,
C6H4Me-2,6), 7.03 (m, 2H), 7.10 (m, 2H), 7.25-7.37 (m, 12H),
7.41 (m, 4H), 7.56 (m, 8H), 8.37 (s+br satellites, 1H). 31P{1H}
NMR (162 MHz, CDCl3): δ 16.65 (1J (Pt,P) ) 4966 Hz). Anal.
Calcd for C51H43ClN2P2Pt2: C, 52.29; H, 3.70. Found: C, 51.91;
H, 3.65. Mp: >260 °C.
1
Yield: 0.30 g, 100%. H NMR (400 MHz, CDCl3): δ -4.06 (t,
2J (P,H) ) 92 Hz, 1J (Pt,H) ) 779 Hz, PtHPt), 0.82-1.03 (m,
6H, PtMe), 6.90-6.95 (m, 2H), 7.30-7.45 (m, 18H), 7.63-7.71
(m, 8H), 10.13 (s, 3J (Pt,H) ) 44 Hz, 1H, NCHN). 31P{1H} NMR
(400 MHz, CDCl3): δ 31.10 (1J (Pt,P) ) 3863 Hz, 2J (Pt,P) )
3
391 Hz, J (P,P) ) 68 Hz). Anal. Calcd for C39H36N2P2Pt2: C,
47.56; H, 3.68; N, 2.84. Found: C, 47.69; H, 3.85; N, 2.97. Mp:
>260 °C.
X-r a y Str u ctu r e Deter m in a tion s. All X-ray measure-
ments were made with a Rigaku AFC-7R diffractometer with
graphite-monochromated Mo KR radiation (λ ) 0.710 69 Å).
Recrystalization of 2f by vapor diffusion of diethyl ether into
a solution of dichloromethane afforded a orange crystal (2f‚
2CH2Cl2). The collected data were solved by Patterson methods
(DIRDIF92 PATTY) and refined by a full-matrix least-squares
procedure using TEXSAN programs. The reflections with |Fo|
> 3σ|Fo| were used in the refinements. All non-hydrogen atoms
were refined with anisotropic displacement parameters. Hy-
drogen atoms were placed in calculated positions and were not
refined. Crystal data and refinement details are summarized
in Table 6.
Recrystallization of 3a by vapor diffusion of diethyl ether
into a solution of dichloromethane afforded a pale yellow
crystal (3a ‚CH2Cl2). The collected data were solved by direct
methods (SIR92) and refined by a full-matrix least-squares
procedure using TEXSAN programs. The reflections with |Fo|
> 3σ|Fo| were used in the refinements. All non-hydrogen atoms
were refined with anisotropic displacement parameters. Hy-
drogen atoms were placed in calculated positions and were not
refined. Crystal data and refinement details are summarized
in Table 6.
P d Me(d p fa m ) (4a ). To a solution of 1 (56 mg, 0.10 mmol)
in acetone (4 mL) was added PdMe2(tmeda) (25 mg, 0.10
mmol). The mixture was stirred at room temperature over-
night to give a yellow precipitate, which was collected by
filtration, washed with a small amount of acetone, and dried.
Yield: 55 mg, 80%. 1H NMR (400 MHz, CDCl3): δ 0.24 (t,
3J (P,H) ) 6.0 Hz, 3H, PdMe), 6.6-6.9 (br, 5H), 7.1-7.7 (br,
23H), 7.72 (s, 1H, NCHN). 31P{1H} NMR (162 MHz, CDCl3):
δ 19.01 (d, 2J (P,P) ) 402 Hz), 35.46 (d, 2J (P,P) ) 402 Hz). Anal.
Calcd for C38H32N2P2Pd: C, 66.62; H, 4.71; N, 4.09. Found:
C, 66.64; H, 4.83; N, 4.12. Mp: 231-233 °C dec.
P tMe(d p fa m ) (4b). This complex was prepared in a man-
ner similar to that above from 1 (56 mg, 0.10 mmol) and PtMe2-
(cod) (33 mg, 0.10 mmol) and isolated as a yellow powder (57
1
3
mg, 74%). H NMR (400 MHz, CDCl3): δ 0.37 (dd, J (P,H) )
2
6.1, 6.8 Hz, J (Pt,H) ) 73 Hz, 3H, PtMe), 6.68-6.77 (m, 2H),
6.80-6.87 (m, 2H), 6.92 (dd, J ) 4.7, 7.8 Hz, 1H), 7.24-7.32
(m, 2H), 7.38-7.56 (m, 13H), 7.61 (m, 4H), 7.69 (m, 4H), 7.81
(s+br satellites, 1H, NCHN). 31P{1H} NMR (162 MHz,
CDCl3): δ 20.54 (d, 2J (P,P) ) 424 Hz, 1J (Pt,P) ) 2368 Hz),
Recrystallization of 4b by slow diffusion of pentane into a
solution of THF afforded a yellow crystal. The collected data
were solved by Patterson methods (SAPI) and refined by a full-
matrix least-squares procedure using TEXSAN programs. The
reflections with |Fo| > 3σ|Fo| were used in the refinements.
All non-hydrogen atoms were refined with anisotropic dis-
placement parameters. Hydrogen atoms were placed in cal-
culated positions and were not refined. Crystal data and
refinement details are summarized in Table 6.
2
1
35.70 (d, J (P,P) ) 424 Hz, J (Pt,P) ) 3002 Hz). Anal. Calcd
for C38H32N2P2Pt: C, 58.99; H, 4.17; N, 3.62. Found: C, 58.87;
H, 4.32; N, 3.66. Mp: >260 °C.
P d P tMe2(µ-Cl)(µ-d p fa m ) (5). To a solution of 4b (77 mg,
0.10 mmol) in benzene (4 mL) was added PdMeCl(cod) (27 mg,
0.10 mmol). The mixture was stirred at room temperature
overnight. Addition of pentane to the reaction mixture led to
the precipitation of a pale yellow powder, which was collected
by filtration, washed with pentane, and dried. Yield: 90 mg,
97%. 1H NMR (500 MHz, CDCl3): δ 0.66 (d, 3J (P,H) ) 1.7 Hz,
Recrystallization of 6 by slow diffusion of pentane into a
solution of benzene afforded a pale yellow crystal (6‚C6H6). The

2528 Organometallics, Vol. 21, No. 12, 2002
Ta ble 6. Cr ysta l Da ta a n d Refin em en t Deta ils for 2f, 3a , 4b, a n d 6
Tsukada et al.
2f‚2CH2Cl2
3a ‚CH2Cl2
4b
6‚C6H6
formula
fw
cryst syst
space group
a (Å)
b (Å)
c (Å)
C39H33N2P2Pd2Cl7
1052.62
monoclinic
P21/n (No. 14)
12.247(6)
18.225(5)
18.541(4)
101.42(2)
92.64(3)
81.81(3)
4
C40H37Cl3N2P2Pt2
1104.23
monoclinic
P21/n (No. 14)
12.67(6)
21.63(7)
14.46(5)
107.24(2)
91.8(3)
93.74(2)
4
C38H32N2P2Pt2
773.72
C45H42N2P2Pt2
1062.97
triclinic
triclinic
P1h (No. 2)
11.302(5)
15.529(4)
9.919(3)
P1h (No. 2)
13.380(3)
14.297(3)
10.830(4)
R (deg)
â (deg)
γ (deg)
Z
112.14(3)
100.54(2)
2
2
V (Å3)
4133(1)
1.691
Mo KR
14.31
3961(25)
1.851
Mo KR
73.40
1576.2(9)
1.630
Mo KR
45.65
ω-2θ
24
1929.3
1.830
Mo KR
73.32
ω-2θ
23
Dcalcd (g cm-3
radiation
)
abs coeff (cm-1
scan mode
)
ω-2θ
ω-2θ
temp (°C)
2θmax (deg)
23
23
50.0
50.1
50.0
50.0
no. of data collected
no. of observns
no. of variables
R (I > 3σ(I))
7909
7427
5854
4778
388
7108
5028
5509
6039
469
442
460
0.075
0.030
0.027
0.031
0.043 (R1)a
0.045 (Rw)a
Rw (I > 3σ(I))
0.100
0.039
a
The structure was refined using the reflection data within 10° < 2θ < 50° by means of the SHELX97 program. R1 is the residual
value for 6039 reflections with I > 2σ(I), and Rw is the residual value for all of the 6728 unique reflections.
collected data were solved by Patterson methods (DIRDIF92
PATTY) and finally refined by a full-matrix least-squares
procedure using another program (SHELX97) in order to
examine more accurately the position of the H(1) atom. After
the refinement was converged for all non-hydrogen atoms
anisotropically, where all hydrogen atoms except for H(1) were
fixed in calculated positions, the resulting difference Fourier
map showed two peaks in the central positions of two Pt atoms
with densities of 1.2 and 1.0 eV/Å3, which were assigned to
H(1) and H(1′), respectively. Only these two hydrogen atoms,
where occupancies of 0.6 and 0.4 are assigned, were refined
using the limited reflections within 20° < 2θ < 40°. As a result,
the positions and thermal temperature factors were refined
reasonably as follows: Pt(1)-H(1) ) 1.66(7), Pt(1)-H(1′) )
1.70(8), Pt(2)-H(1) ) 1.63(8), Pt(2)-H(1′) ) 1.69(8) Å; Pt(1)-
H(1)-Pt(2) ) 117.0(8), Pt(1)-H(1′)-Pt(2) ) 111(1)°. These
results show that the hydrogen atom attached to Pt(1) and
Pt(2) was disordered with approximately the same Pt-H bond
lengths. Finally, all non-hydrogen atoms were refined aniso-
tropically using all unique reflections within 10° < 2θ < 50°,
where the H(1) and H(1′) hydrogen atoms were again fixed.
Ack n ow led gm en t. We are indebted to Dr. Chizuko
Kabuto for helpful discussions of the crystallography of
6.
Su p p or tin g In for m a tion Ava ila ble: Tabulations of crys-
tallographic data, positional and thermal parameters, and
bond lengths and angles for 2f, 3a , 4b, and 6. This material
is available free of charge via the Internet at http://pubs.acs.org.
OM020003F