Syntheses, Structures, and Reactivity of Dinuclear Molybdenum-Platinum and Tungsten-Platinum Complexes with Bridging Carbonyl, Sulfur Dioxide, Isonitrile, and Aminocarbyne Ligands and a dppa Backbone (dppa = Ph2PNHPPh2)

Article abstract of DOI:10.1021/om980756v

The heterodinuclear μ-carbonyl complexes [(OC)₄M(μ-CO)(μ-dppa)Pt(PPh₃)] (3a, M = Mo; 3b, M = W) are formed upon the reaction of [(OC)₅M(η¹-dppa)] (1a, M = Mo; 1b, M = W) with [Pt(C₂H₄)(PPh₃)₂]. After addition of p-tosylmethyl isonitrile to 3, the CO bridge is replaced by a bridging isonitrile ligand to afford [(OC)₄W(μ-C=NCH₂SO ₂p-tolyl)(μ-dppa)Pt-(PPh₃)] (4a, M = Mo; 4b, M = W). If stronger electron-donating isonitriles such as benzyl or 2,6-xylyl isonitrile are added to 3, fragmentation into mononuclear complexes occurs. Protonation of 4 leads to the μ-aminocarbyne complexes [(OC)₄M{μ-CN(H)CH₂SO ₂p-tolyl}-(μ-dppa)Pt(PPh₃)][BF₄] (5a, M = Mo; 5b, M = W), which react further with isonitriles to yield the μ-aminocarbyne complexes [(OC)₃(RNC)W{μ-CN(H)CH₂SO ₂p-tolyl}(μ-dppa)Pt-(PPh₃)][BF₄] 6, (R = 2,6-xylyl, benzyl). Purging a solution of 4a with SO₂ yields the complex [(OC)₄Mo(μ-SO₂)(μ-dppa)Pt(PPh₃)], 7a, in which a triphenylphosphine oxide ligand is bound via a hydrogen bridge to the N-H group of the dppa backbone. X-ray diffraction studies performed on 4b and 7a reveal that the μ-CNR and the μ-SO₂ ligands bridge the metal centers in an asymmetric manner, the Pt-μ-C or Pt-μ-S distances being significantly shorter than the corresponding W-μ-C or Mo-μ-S distances, respectively.

Full text of DOI:10.1021/om980756v

248
Organometallics 1999, 18, 248-257
Syn th eses, Str u ctu r es, a n d Rea ctivity of Din u clea r
Molybd en u m -P la tin u m a n d Tu n gsten -P la tin u m
Com p lexes w ith Br id gin g Ca r bon yl, Su lfu r Dioxid e,
Ison itr ile, a n d Am in oca r byn e Liga n d s a n d a d p p a
Ba ck bon e (d p p a ) P h 2P NHP P h 2)
Michael Knorr*,†,‡ and Carsten Strohmann§
Anorganische Chemie, Universita¨t des Saarlandes, Postfach 151150,
D-66041 Saarbru¨cken, Germany and Institut fu¨r Anorganische Chemie der
Universita¨t Wu¨rzburg, Am Hubland, D-97074 Wu¨rzburg, Germany
Received September 9, 1998
The heterodinuclear µ-carbonyl complexes [(OC)4M(µ-CO)(µ-dppa)Pt(PPh3)] (3a , M ) Mo;
3b, M ) W) are formed upon the reaction of [(OC)5M(η1-dppa)] (1a , M ) Mo; 1b, M ) W)
with [Pt(C2H4)(PPh3)2]. After addition of p-tosylmethyl isonitrile to 3, the CO bridge is
replaced by a bridging isonitrile ligand to afford [(OC)4W(µ-CdNCH2SO2p-tolyl)(µ-dppa)Pt-
(PPh3)] (4a , M ) Mo; 4b, M ) W). If stronger electron-donating isonitriles such as benzyl or
2,6-xylyl isonitrile are added to 3, fragmentation into mononuclear complexes occurs.
Protonation of 4 leads to the µ-aminocarbyne complexes [(OC)4M{µ-CN(H)CH2SO2p-tolyl}-
(µ-dppa)Pt(PPh3)][BF4] (5a , M ) Mo; 5b, M ) W), which react further with isonitriles to
yield the µ-aminocarbyne complexes [(OC)3(RNC)W{µ-CN(H)CH2SO2p-tolyl}(µ-dppa)Pt-
(PPh3)][BF4] 6, (R ) 2,6-xylyl, benzyl). Purging a solution of 4a with SO2 yields the complex
[(OC)4Mo(µ-SO2)(µ-dppa)Pt(PPh3)], 7a , in which a triphenylphosphine oxide ligand is bound
via a hydrogen bridge to the N-H group of the dppa backbone. X-ray diffraction studies
performed on 4b and 7a reveal that the µ-CNR and the µ-SO2 ligands bridge the metal
centers in an asymmetric manner, the Pt-µ-C or Pt-µ-S distances being significantly shorter
than the corresponding W-µ-C or Mo-µ-S distances, respectively.
In tr od u ction
as a two-electron donor, two metal centers of the same
triad with a square planar coordination sphere. This
paucity of heterobimetallic M(µ-CNR)M′ systems mark-
edly contrasts the numerous examples of heterobime-
tallics and higher-nuclearity metal clusters reported in
the literature possessing terminal isonitrile ligands.
However, a bent or linear µ-CNR bonding mode is not
uncommon in homobimetallic M(µ-CNR)M systems. The
first complex of the bent type, [(OC)CpFe(µ-CdNPh)-
(µ-CO)Fe(CO)Cp], has already been structurally char-
acterized by Pauson et al. in 1965.3a In more recent
papers the groups of Yamamoto and Mingos have shown
that bridging isonitrile ligands in homobimetallic and
cluster compounds may even adopt a nearly linear Cd
N-R arrangement.3b-d
We were therefore interested in heterodinuclear M(µ-
CNR)M′ complexes containing metal centers possessing
different coordination geometries and oxidation states
in order to determine the steric and/or electronic effects
governing the bonding mode (bridging vs terminal) of
CNR ligands in heterometallic systems.4 In the case of
the bridging bonding mode some structural questions
of interest concern (i) the angle CdN-R (linear A vs
bent B), (ii) the relative orientation of the group R
Despite the importance of isonitriles as ligands and
substrates in organometallic and coordination chemis-
try, studies concerning structure and reactivity of
1
heterobimetallics M(µ-CNR)M′ possessing an isonitrile
bridge between two different metal centers are still
extremely scarce. The only representatives known so far
are the A-frame complex [C6F5Pd(µ-CdNp-tolyl)(µ-
dppa)2PtC6F5] and the structurally characterized Ni-
Pt complex [(MeCN)Ni(µ-CdNMe)(µ-dppm)2PtCl][Cl].2
These two complexes resulted from formal insertion of
CNR into the metal-metal bond of [C6F5Pd(µ-dppa)2-
PtC6F5] or were obtained by transmetalation reaction
of [(MeCN)Ni(µ-CdNMe)(µ-dppm)2Ni(CNMe)] with [Pt-
(dppm)Cl2].2 In both cases, the µ-isonitrile ligand spans,
† Universita¨t des Saarlandes.
‡ Present address: Laboratoire de Chimie de Coordination, UMR
CNRS 7513, Universite´ Louis Pasteur, 4 rue Blaise Pascal, F-67070
Strasbourg, France. E-mail: mknorr@chimie.u-strasbg.fr.
§ Universita¨t Wu¨rzburg.
(1) (a) Yamamoto, Y. Coord. Chem. Rev. 1980, 32, 193. (b) Singleton,
E.; Oosthuizen, H. E. Adv. Organomet. Chem. 1983, 22, 209. (c) Lentz,
D. Angew. Chem. 1994, 106, 1377. (d) Fehlhammer, W. P.; Fritz, M.
Chem. Rev. 1993, 1243.
(2) (a) Fornies, J .; Martinez, F.; Navarro, R.; Redondo, A.; Tomas,
M.; Welch, A. J . J . Organomet. Chem. 1986, 316, 351. (b) Rattliff, K.
S.; Fanwick, P. E.; Kubiak, C. P. Polyhedron 1990, 9, 2651. (c) For a
very recent example of a dppm-bridged Mo-W complex with an
unusual µ-η1:η2-CNR ligand acting as four-electron donor, see: Alvarez,
C.; Garcia, M.; E.; Riera; V.; Ruiz, M. A. Organometallics 1997, 16,
1378.
(3) (a) J oshi, K. K.; Mills, O. S.; Pauson, P. L.; Shaw, B. W.; Stubbs,
W. H. Chem. Commun. 1965, 181. (b) Yamamoto, Y.; Yamazaki, H.
Inorg. Chem. 1986, 25, 3327. (c) Burrows, A. D.; Fleischer, H.; Mingos,
D. M. P. J . Organomet. Chem. 1992, 433, 311. (d) Burrows, A. D.; Hill,
C. M.; Mingos, D. M. P. J . Organomet. Chem. 1993, 456, 155.
10.1021/om980756v CCC: $18.00 © 1999 American Chemical Society
Publication on Web 12/29/1998

Dinuclear Mo-Pt and W-Pt Complexes
Organometallics, Vol. 18, No. 2, 1999 249
toward M or M′ for the bent case (B and B′), and iii)
the position of the CNR bridge between the two metal
centers (symmetric bonding mode A/B or asymmetric
bridging bonding mode C).
bridging carbene, vinylidene, carbyne, and isonitrile
ligands,4,8 we report some results on the solid-state
structures, synthesis, and reactivity of dppa-bridged
Mo-Pt and W-Pt complexes with bridging isonitrile
ligands.
Resu lts a n d Discu ssion
Syn th esis of th e Meta llop h osp h in es [(OC)5M(η1-
d p p a )]. Metal complexes LnM(η1-R2PXPR2) containing
a dangling diphosphine ligand are useful precursors for
assembling polymetallic systems,9 and numerous homo-
and heterobimetallics have been prepared with bis-
(diphenylphosphino)methane.7 We have already suc-
cessfully employed [(OC)4Fe(η1-dppa)] as metallophos-
phine for the preparation of Fe-Pt and Fe-Re com-
plexes.4b,5c,d It seemed therefore promising to employ
related metallophosphines of the type [(OC)5M(η1-dppa)]
(M ) Mo, W) for the synthesis of dppa-bridged Mo-Pt
and W-Pt compounds. Treatment of [(OC)5M(NCMe)]
with dppa in a 1:1 ratio afforded the metallophosphines
1 with a pendant dppa ligand (31P{1H} in CDCl3 1a , δ
Apart from this structural aspect, our objective is to
use the presence of two different metal centers for a
bimetallic activation of the isonitrile ligand for further
transformations such as carbon-carbon coupling reac-
tions or conversion to µ-aminocarbyne ligands.
2
83.9 (d, P1(Mo), J (P1-P2) ) 65 Hz), 32.9 (d, P2); 1b,
2
1
63.7 (d, P1(W), J (P1-P2) ) 59 Hz, J (P-W) 192 Hz),
32.7 (d, P2)), together with the literature known chelate
complexes 2.10,11 Whereas in the case of M ) Mo only
minor amounts of 2a are formed (86% yield of 1a ), the
isolation of pure 1b (24%) was more difficult due to the
formation of the chelate complex [(OC)4W(dppa)] (2b)
as the major species. Elemental analysis, 1H NMR, and
the X-ray diffraction studies (see below) indicate the
coordination of one molecule of acetonitrile bound via a
hydrogen bridge to the dppa ligand of 1 and 2.
Since no structural information about bis(diphe-
nylphosphino)amine-bridged heterobimetallic systems
is available apart from our very recent studies on
dinuclear dppa-bridged Fe-Pt systems,4b we have cho-
sen this diphosphine ligand5,6 to stabilize the metal-
metal bond instead of the very common bis(diphenylphos-
phino)methane (dppm) ligand.7 Recent comparative IR
studies have established that dppa is somewhat less
electron donating than dppm.5d We have shown that the
selective substitution of the µ-CO ligand of [(OC)3(Fe-
(µ-CO)(µ-dppa)Pt(PPh3)] by a CNR ligand offers a
convenient access to complexes of the type [(OC)3(Fe-
(µ-CdNR)(µ-dppa)Pt(PPh3)].4b With the aim to investi-
gate heterobimetallic systems containing metal couples
that are more separated in the periodic table than iron
and platinum, we set out to prepare CO-bridged het-
erodinuclear Mo-Pt and W-Pt and to use them for the
preparation of Mo(µ-CNR)Pt or W(µ-CNR)Pt complexes.
In the context of our studies on heterobimetallics with
The X-ray structure determination of the metallo-
ligand 1a (Figure 1, Table 1) revealed that the overall
geometry and bond lengths of the Mo(CO)5P fragment
are comparable to other complexes of the type [Mo-
(4) (a) Knorr, M.; Faure, T.; Braunstein, P. J . Organomet. Chem.
1993, 447, C4. (b) Knorr, M.; Strohmann, C. Eur. J . Inorg. Chem. 1998,
495. (c) Knorr, M. Habilitation Thesis, Universita¨t des Saarlandes,
1997. (d) Knorr, M.; Strohmann, C. Poster abstract 98, 4th Anglo/
German Inorganic Chemistry Meeting, University of Marburg, 1997.
(5) Examples for dppa-bridged heterobimetallics: (a) Blagg, A.;
Cooper, G. R.; Pringle, P. G.; Robson, R.; Shaw, B. L. J . Chem. Soc.,
Chem. Commun. 1984, 14, 933. (b) Uson, R.; Fornies, J .; Navarro, R.;
Cebollada, J . I. J . Organomet. Chem. 1986, 304, 381. (c) Knorr, M.;
Braunstein, P.; Tiripicchio, A.; Ugozzoli, F. J . Organomet. Chem. 1996,
526, 105. (d) Knorr, M.; Hallauer, E.; Huch, V.; Veith, M.; Braunstein,
P. Organometallics 1996, 15, 3868.
(6) Examples for dppa-bridged homobimetallics: (a) Ellermann, J .;
Szucsanyi, G.; Geibel, K.; Wilhelm, E. J . Organomet. Chem. 1984, 263,
297. (b) Liehr, G.; Szucsanyi, G.; Ellermann, J . J . Organomet. Chem.
1984, 265, 95. (c) Ellermann, J .; Gabold, P.; Knoch, F. A.; Moll, M.;
Pohl, D.; Sutter, J .; Bauer, W. J . Organomet. Chem. 1996, 525, 89. (d)
Derringer, D. R.; Fanwick, P. E.; Moran, J .; Walton, R. A. Inorg. Chem.
1989, 28, 1384. (e) Steil, P.; Nagel, U.; Beck, W. J . Organomet. Chem.
1989, 366, 313. (f) Schmidbaur, H.; Wagner, F. E.; Wohlleben-Hammer,
A. Chem. Ber. 1979, 17, 846. (g) Cotton, F. A.; Kuehn, F. E. J . Am.
Chem. Soc. 1996, 118, 5826. See also: (f) Balakrishna, M. S.; Reddy,
V. S.; Krishnamurty, S. S.; Nixon, J . F.; Laurent, J . C. T. R. B. S. Coord.
Chem. Rev. 1994, 129, 1.
(8) (a) Knorr, M.; Braunstein, P.; DeCian, A.; Fischer, J . Organo-
metallics 1995, 14, 1302. (b) Knorr, M.; Braunstein, P.; Tiripicchio,
A.; Ugozzoli, F. Organometallics 1995, 14, 4910. (c) Knorr, M.;
Strohmann, C.; Braunstein, P. Organometallics 1996, 15, 5653.
(9) (a) Sato, F.; Uemura, T.; Sato, M. J . Organomet. Chem. 1973,
56, C27. (b) Blagg, A.; Shaw, B. L. J . Chem. Soc., Dalton Trans. 1987,
221. (c) Fontaine, X. L. R.; J acobsen, G. B.; Shaw, B. L.; Thornton-
Pett, M. J . Chem. Soc., Chem. Commun. 1987, 663. (d) Takats, J .; Kiel,
G. Y. Organometallics 1989, 8, 839. (e) Braunstein, P.; Knorr, M.;
Schubert, U.; Lanfranchi, M.; Tiripicchio, A. J . Chem. Soc., Dalton
Trans. 1991, 1507. (f) Cano, M.; Ovejero, P.; Heras, J . V. J . Organomet.
Chem. 1992, 438, 329. (g) Gan K. S.; Lee, H. K.; Hor, T. S. A. J .
Organomet. Chem. 1993, 460, 197. (h) Braunstein, P.; Knorr, M.;
Strampfer, M.; Dusausoy, Y.; Bayeul, D.; DeCian, A.; Fischer, J .;
Zanello, P. J . Chem. Soc., Dalton Trans. 1994, 1533. (i) Xu, C.;
Anderson, G. K. Organometallics 1994, 13, 3981. (j) Liu, L. K.; Luh,
L. S.; Wen, Y. S.; Eke, U. B.; Mesubi, M. A. Organometallics 1995, 14,
4474. (k) Browning, G. S.; Farrar, D. H. J . Chem. Soc., Dalton Trans.
1995, 521.
(10) The analogous dppm derivatives of
1 have already been
described: (a) Keiter, R. L.; Shah, D. P. Inorg. Chem. 1972, 11, 191.
(b) Hor, T. S. A. J . Organomet. Chem. 1987, 319, 213.
(11) (a) Payne, D. S.; Walker, A. P. J . Chem. Soc. (C) 1966, 498. (b)
Ellermann, J .; Wend, W. Nouv. J . Chim. 1986, 10, 313.
(7) (a) Puddephatt, R. J . Chem. Soc. Rev. 1983, 99. (b) Chaudret,
B.; Delavaux, B.; Poilblanc, R. Coord. Chem. Rev. 1988, 86, 191. (c)
Mague, J . T. J . Cluster Sci. 1995, 6, 217.

250 Organometallics, Vol. 18, No. 2, 1999
Knorr and Strohmann
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for Com p lex 2a
Mo-P(1)
Mo-P(2)
Mo-C(1)
Mo-C(2)
Mo-C(3)
Mo-C(4)
P(1)-N(1)
P(2)-N(1)
2.501(3)
2.495(2)
1.989(4)
1.993(4)
2.013(5)
2.040(4)
1.685(3)
1.684(3)
P(1)-N(1)-P(2)
P(1)-Mo-P(2)
P(1)-Mo-C(1)
P(2)-Mo-C(2)
P(1)-Mo-C(2)
P(2)-Mo-C(1)
N(1)-P(1)-Mo
N(1)-P(2)-Mo
106.2(2)
65.29(6)
164.7(1)
169.0(1)
103.3(1)
99.6(1)
94.2(1)
94.4(1)
Noteworthy is the very acute angle P(1)-Mo-P(2) of
65.29(6)°, thus bringing the two phosphorus atoms P(1)
and P(2) in close contact with a separation of only 2.694-
(3) Å.
Syn th esis of µ-CO-Br id ged Heter obim eta llics.
Upon addition of [Pt(C2H4)(PPh3)2] to a solution of 1a ,b
in toluene, rapid evolution of ethylene occurred at
ambient temperature, giving the yellow carbonyl-
bridged [(OC)4M(µ-CO)(µ-dppe)Pt(PPh3)] heterobime-
tallic complexes 3a ,b in more than 80% yield. Com-
plexes 3 are air stable in the solid state for several
hours, but begin slowly to decompose in solution after
several hours at ambient temperature. They are highly
soluble in chlorinated solvents such as CH2Cl2 and
CHCl3 and possess a moderate solubility in toluene, but
are nearly insoluble in hexane and diethyl ether.
F igu r e 1. View of the crystal structure of [(OC)5Mo(dppa)]‚
MeCN (1a ) with the atom-numbering scheme.
Ta ble 1. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for Com p lex 1a
Mo-P(1)
Mo-C(1)
Mo-C(2)
Mo-C(3)
Mo-C(4)
Mo-C(5)
P(1)-N(1)
P(2)-N(1)
2.517(4)
1.999(5)
2.038(4)
2.038(4)
2.028(5)
2.033(4)
1.682(3)
1.718(4)
P(1)-N(1)-P(2)
N(1)-N(2)-C(30)
P(1)-Mo-C(1)
P(1)-Mo-C(4)
P(1)-Mo-C(5)
P(1)-Mo-C(3)
P(1)-Mo-C(2)
N(1)-P(1)-Mo
124.3(2)
131.2(4)
178.3(1)
91.3(2)
90.2(2)
89.8(2)
88.7(2)
112.4(2)
The proposed structure of the heterobimetallic com-
pounds 3 in solution could be deduced from the com-
bined NMR and IR data. The 31P{1H} NMR spectra of
3 display AMX patterns for the three mutually coupled
phosphorus nuclei. The IR spectra of 3 in CH2Cl2 show
three ν(CO) vibrations for the terminal carbonyls (3a ,
2021 s, 1914 vs, br, 1890 sh; 3b, 2018 s, 1908 vs, br)
and a further vibration of medium intensity for the
bridging carbonyl ligand (3a , 1805; 3b, 1791 cm-1). The
solid-state IR spectrum of 3b contains a sharp absorp-
tion band assigned to the N-H vibration (3318 cm-1),
which indicates the absence of hydrogen bonds as
encountered in 1.
Syn th esis of µ-CNR-Br id ged Heter obim eta llics.
Reaction of 3 with 1 equiv of p-tosylmethyl isonitrile
led within 10 min to selective substitution of the
bridging carbonyl to afford the yellow isonitrile-bridged
complexes [(OC)4M(µ-CdNCH2SO2p-tolyl)(µ-dppa)Pt-
(PPh3)] (4a , M ) Mo; 4b, M ) W) according to Scheme
1. Although these µ-CNR complexes are stable for
months in the solid state under a nitrogen atmosphere,
they gradually decompose in solution after several
hours, especially the Mo-Pt complex 4a , which pos-
sesses a limited stability even at - 25 °C. Among the
decomposition products, which have not been analyzed
in detail, the chelates [(OC)4M(dppa)] are always found.
F igu r e 2. View of the crystal structure of [(OC)4Mo(dppa)]‚
MeCN (2a ) with the atom-numbering scheme.
(CO)5PR3].12 The distance P(1)-N(1) of 1.682(3) Å is
similiar to that reported for uncomplexed dppa (1.692-
(2) Å), whereas the distance P(2)-N(1) of 1.718(4) Å is
somewhat elongated. The angle P(1)-N(1)-P(2) of
124.3(2)° is widened compared to that reported for the
free ligand (118.9(2)°).13 An acetonitrile molecule is
weakly bound to the N-H group (d(N(1)-N(2)) 3.291-
(6) Å) of the dppa ligand. The presence of a hydrogen-
bonded acetonitrile molecule (d(N(1)-N(2)) 3.088(5) Å)
was also confirmed by an X-ray structure determination
for the chelate complex 2a (Figure 2). The bond lengths
and angles of 2a (Table 2) are very close to that reported
for the chelate complex [(OC)4Mo(Ph2PNEtPPh2)].14
(12) Cotton, F. A.; Darensbourg, D. J .; Ilsley, W. H. Inorg. Chem.
1981, 20, 578.
(13) (a) No¨th, H.; Meinel, E. Z. Anorg. Allg. Chem. 1967, 349, 744.
(b) No¨th, H.; Fluck, E. Z. Naturforsch. 1984, 39b, 225.
(14) (a) Payne, D. S.; Mokuolo, J . A. A.; Speakman, J . C. J . Chem.
Soc., Chem. Commun. 1965, 599. (b) For [(OC)4Mo(dppm)] see: Che-
ung, K. K.; Lai, T. F.; Mok, K. S. J . Chem. Soc. (A) 1971, 1644.

Dinuclear Mo-Pt and W-Pt Complexes
Organometallics, Vol. 18, No. 2, 1999 251
Sch em e 1
of benzyl isonitrile to a CH2Cl2 solution of 3b a broad-
ened ν(CtN) vibration of medium intensity, diagnostic
for a terminal bound isonitrile ligand, has been observed
at 2148 cm-1 besides three further ν(CO) stretches at
2018 (m), 1903 (vs, br), and 1792 (m) cm-1. This
heterobimetallic intermediate fragments within minutes
to mononuclear species, so that attempts to obtain
unambiguous evidence for the existence of [(OC)3-
(RNC)M(µ-CO)(µ-dppa)Pt(PPh3)] by 31P NMR monitor-
ing remained unsuccessful. In a typical experiment
using benzyl isonitrile, only several sets of doublets of
doublets (δ 65.2 and 27.7, J (P-P) ) 26 Hz; δ 64.6 and
29.8, J (P-P) ) 44 Hz) have been detected together with
the singlet resonance due to [(OC)4W(dppa)].15 Note that
in the case of the related dppm and dppa-bridged Fe-
Pt complex [(OC)4(Fe(µ-CO)(µ-Ph2PXPPh2)Pt(PPh3)] with
benzyl isonitrile or 2,6-xylyl isonitrile the stable µ-CNR
complexes [(OC)3(Fe(µ-CNR)(µ-Ph2PXPPh2)Pt(PPh3)] (X
) CH2, NH) have been isolated as the sole products and
structurally characterized by X-ray diffraction.4b-d We
assume that in the case of the Mo-Pt and W-Pt
systems no steric reasons are responsible for the lability
of the isonitrile-substituted derivatives. It seems that
predominantly the additional electron-donating influ-
ence of isonitriles, which are in general considered to
be better σ-donors and weaker π-acceptors compared to
a CO ligand, destabilizes these electron-rich heterobi-
metallic systems (three phosphorus donors and two
metal centers in low oxidation states). Only in the case
of p-tosylmethyl isonitrile possessing a strong electron-
withdrawing SO2-p-tolyl group does the π-acceptor
capacity seem to be sufficient to prevent fragmentation.
Theoretical calculations of Howell et al. on the bonding
properties of isonitriles predict that the σ-donor char-
acter of isonitriles in a bridging bonding mode is
comparable to that of linear terminal isonitrile ligands.
However, the π-acceptor capacity strongly depends on
the angle CdN-R and may even surpass that of carbon
monoxide, if the degree of bending is significant enough.16
This may explain why in the solid-state structure of 4b
a strong bending of 126.8° (see below) has been ob-
served. Of course, the impact of packing effects may also
influence the degree of the bending in the solid-state
structure. Thus the combination of two factorssthe
electron withdrawing character of the CH2SO2p-tolyl
group and its extreme bendingspermits the p-tosylm-
ethyl isonitrile ligand to compensate at least partially
the electron-donating influence of the three phosphorus
donors by back-bonding into its π* orbitals. Further
studies with other isonitriles possessing electron-
withdrawing groups will show whether other stable
complexes of the type [(OC)4M(µ-CNR)(µ-Ph2PXPPh2)-
Pt(PPh3)] are accessible.
Sp ectr oscop ic Stu d ies. The NMR features of 4
resemble in general those of the precursors 3. For
instance, the 31P{1H} NMR spectrum of 4b displays a
doublet of doublets at δ 71.2 assigned to the platinum-
bound dppa-phosphorus atom, which is strongly coupled
(
2+3J (P-P) ) 134 Hz) with the tungsten-bound dppa
phosphorus at δ 58.1. These signals are further split
due to the presence of the PPh3 ligand. The latter gives
rise to a doublet of doublets at δ 43.7 with couplings of
39 and 56 Hz. All signals are flanked by 195Pt satellites,
whose Pt-P couplings are also found in the 195Pt NMR
spectrum (ddd at δ -2682 with 1J (Pt-P) couplings of
4448 and 3253 Hz and a further 2+3J (Pt-P) coupling of
49 Hz). Compared to the 31P data of the µ-CO counter-
parts 3, the following trends are noticeable: substitution
of CO by CNR causes a lowering of the 2+3J (P-P)
coupling (166 Hz 3b vs 134 Hz 4b) and 1J (Pt-P2)
coupling (3734 Hz vs 3253 Hz), whereas the J (Pt-P3)
1
coupling (4199 Hz vs 4448 Hz) rises. The chemical shifts
of the doublet of doublets of doublets resonances mea-
sured in the 195Pt{1H} NMR spectra of 3 and 4 are
affected by neither the nature of the metal adjacent to
the 195Pt nucleus nor the CdY bridge (Y ) O, NR) and
are found in the very narrow range between δ -2656
and -2682 ppm. The most significant change in the IR
spectra of 4 is the replacement of the ν(CO) stretch of
the bridging carbonyl of 3 against a broadened intense
ν(CdN) stretch (4a : 1677; 4b: 1669 cm-1). These
absorptions appear in the region typical for bridging
isonitrile ligands; for example, the ν(CdN) stretch of
corresponding Fe-Pt complex [(OC)3Fe(µ-CdNCH2-
SO2p-tolyl)(µ-dppa)Pt(PPh3)] has been detected at 1648
Cr ysta l Str u ctu r e of [(OC)4W(µ-CdNCH2SO2p-
tolyl)(µ-d p p a )P t(P h 3)] (4b). The proposed structure
of 4b (Figure 3, Table 3) in solution was also confirmed
cm-1 4b,c
.
Despite our efforts, we could not succeed in isolating
or characterizing even in solution by NMR spectroscopy
any CNR derivatives with a CNR bridge analogous to
4 after stoichiometric addition of more nucleophilic
isonitriles such as benzyl isonitrile or 2,6-xylyl isonitrile.
IR monitoring revealed that immediately after isonitrile
addition substitution of a terminal CO ligand occurs
probably with formation of [(OC)3(RNC)M(µ-CO)(µ-
dppa)Pt(PPh3)]. For example, 5 min after the addition
(15) (a) In the case of the reaction of [(OC)4W(µ-CO)(µ-dppm)Pt-
(PPh3)] with benzyl isonitrile the isonitrile-substituted metallophos-
phine [(OC)4(BzNC)W(η1-dppm)] has been isolated. (b) Knorr, M.
Unpublished results.
(16) (a) Howell, J . A. S.; Saillard, J .-Y.; Le Beuze, A.; J aouen, G. J .
Chem. Soc., Dalton Trans. 1982, 2533. (b) The π-acceptor ability and
bending of the µ-CdN-R moiety and the comparison with a µ-CdO
group has also been investigated by means of Fenske-Hall calculations
for complexes of the type W2(OH)6(µ-CNR) and W2(OH)6(µ-CO): Ch-
isholm, M. H.; Clark, D. L.; Ho, D.; Huffman, J . C. Organometallics
1987, 6, 1532.

252 Organometallics, Vol. 18, No. 2, 1999
Knorr and Strohmann
Ta ble 3. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for Com p lex 4b
Pt-W
2.810(2)
1.944(11)
2.271(3)
2.303(3)
2.498(3)
2.309(10)
1.97(2)
2.02(2)
2.004(13)
2.02(2)
1.229(12)
1.436(13)
1.779(11)
1.439(8)
1.432(11)
1.703(9)
1.688(10)
119.6(6)
126.8(10)
110.8(8)
Pt-C(1)-W
82.2(4)
43.3(3)
54.5(3)
Pt-C(1)
C(1)-W-Pt
Pt-P(3)
C(1)-Pt-W
Pt-P(2)
C(1)-W-P(1)
C(1)-Pt-P(2)
C(1)-Pt-P(3)
P(2)-Pt-P(3)
W-Pt-P(3)
105.3(3)
151.0(3)
97.9(3)
108.60(10)
150.38(8)
100.78(8)
75.94(7)
104.7(5)
162.0(5)
84.9(5)
77.5(5)
71.1(4)
175.6(4)
85.0(4)
89.6(4)
W-P(1)
W-C(1)
W-C(10)
W-C(11)
W-C(12)
W-C(13)
C(1)-N(1)
C(2)-N(1)
C(2)-S
W-Pt-P(2)
Pt-W-P(1)
C(1)-W-C(13)
C(1)-W-C(12)
C(1)-W-C(11)
C(1)-W-C(10)
C(13)-W-Pt
P(1)-W-C(10)
P(1)-W-C(13)
P(1)-W-C(12)
P(1)-W-C(11)
C(2)-S-C(3)
O(1)-S
O(2)-S
P(1)-N(2)
P(2)-N(2)
P(1)-N(2)-P(2)
C(1)-N(1)-C(2)
N(1)-C(2)-S
88.6(4)
106.1(6)
F igu r e 3. View of the crystal structure of [(OC)4W(µ-
CNCH2SO2p-tolyl)(µ-dppa)Pt(PPh3)] (4b ) with the atom-
numbering scheme.
by a single-crystal X-ray diffraction study in the solid
state. The W-Pt distance of 2.810(2) Å indicates a
metal-metal bond and is close to the values found in
other complexes of this type.17 The tungsten and plati-
num atoms are linked by a dppa bridge. The bridging
isonitrile ligand is extremely asymmetrically situated
between the two metals with W-C(1) and Pt-C(1)
distances of 2.309(10) and 1.944(11) Å, respectively. A
very similar asymmetric arrangement has been encoun-
tered for Stone’s carbene-bridged compounds [(OC)4W-
(µ-C(OMe)p-tolyl)(µ-dppm)Pt(CO)] and [(OC)5W(µ-Cd
CH2)Pt(dppm)].17a,b For the former dppm-bridged com-
plex, the asymmetry of the three-membered Pt{µ-
C(OMe)p-tolyl}W ring [Pt-C 1.97(3), W-C 2.49(3) Å]
is even more accentuated than in the case of 4b. This
asymmetry has been discussed in terms of a formal
coordination of a R(MeO)CdPtL2 moiety to a W(CO)4-
PR3 fragment. The length of the C(1)-N(1) double bond
of 1.229(12) Å is comparable to that reported for other
isonitrile-bridged systems.18 The C(1)-N(1)-C(2) angle
is strongly bent (126.8(10)°) and aligned parallel to the
Pt-W axis, with the tosylmethyl group oriented toward
the tungsten center. This inclination exceeds the C-N-C
angle of the µ-CdN-Me ligand of [(MeCN)Ni(µ-CdNMe)-
(µ-dppm)2PtCl][Cl],2b which amounts to 132.3° (from
Cambridge Data Base). We believe that this strong
bending may have its origin in electronic reasons (see
above); however, the orientation toward the carbonyl
fragment is imposed by the steric bulkiness of the
triphenyl phosphine ligand on platinum, which would
otherwise interfere in a unfavorable manner with the
p-tosylmethyl group. The coordination about the seven-
coordinate tungsten atom is completed by four terminal
F igu r e 4. Perspective view of the core structure of 4b
along the W-Pt axis. The phenyl groups are omitted for
clarity.
CO ligands and may be viewed as distorted octahedral
(when neglecting the metal-metal bond) and that of the
Pt atom as distorted square planar. The rms deviation
from the mean plane defined by Pt, W, P(2), P(3), and
C(1) has been determined to be 0.169 Å. The mutual
inclination of the two metal fragments, which is mani-
fested in the torsion angle P(1)-W-Pt-P(2) of 31.6(1)°
between the two dppa-phosphorus atoms, can be seen
in Figure 4 showing the core structure of 4b along the
W-Pt axis.
Syn th esis of Ca tion ic µ-Am in oca r byn e Com -
p lexes. We have recently shown that the addition of
various electrophiles to the basic nitrogen of the isoni-
trile bridge of complexes of the type [(OC)3Fe{µ-CNR}-
(µ-Ph2PXPPh2)Pt(PPh3)] represents a convenient method
for the preparation of heterobimetallics bridged by an
aminocarbyne ligand, a class of compound that has been
previously unknown.4,19 To probe whether in the case
(17) (a) Mead, K. A.; Moore, I.; Stone, F. G. A.; Woodward, P. J .
Chem. Soc., Dalton Trans. 1983, 2083. (b) Awang, M. R.; J effery, J .
C.; Stone, F. G. A. J . Chem. Soc., Dalton Trans. 1983, 2091. (c)Awang,
M. R.; Barr, R. D.; Green, M.; Howard, J . A. K.; Marder, T. B.; Stone,
F. G. A. J . Chem. Soc., Dalton Trans. 1985, 2009. (d) Powell, J .; Sawyer,
J . F.; Smith, S. J . J . Chem. Soc., Chem. Commun. 1985, 1312. (e)
Lukehart, C. M.; True, W. R. Organometallics 1988, 7, 2387. (f)
Braunstein, P.; Bellefon, C. D. M. D.; Oswald, B.; Ries, M.; Lanfranchi,
M.; Tiripicchio, A. Inorg. Chem. 1993, 32, 1638.
(18) (a) Olmstead, M. M.; Hope, H.; Benner, L. S.; Balch, A. L. J .
Am. Chem. Soc. 1977, 99, 5502. (b) Busetto, L.; Carlucci, L.; Zanotti,
V.; Albano, V. G.; Braga, D. J . Chem. Soc., Dalton Trans. 1990, 243.
(c) Wu, W.; Fanwick, P. E.; Walton, R. A. Organometallics 1997, 16,
1538. (d) Ruiz, J .; Riera, V.; Vivanco, M.; Garcia-Granda, S.; Pertierra,
P. Organometallics 1992, 11, 2734. (e) DeLaet, D. L.; Fanwick, P. E.;
Kubiak, C. P. Organometallics 1986, 5, 1807.
(19) A µ-CN(Et)Me-bridged W-Au aminocarbyne complex has been
recently structurally described: Albano, V. G.; Busetto, L.; Cassani,
M. C.; Sabatino, P.; Schmitz, A.; Zanotti, V. J . Chem. Soc., Dalton
Trans. 1995, 2087.

Dinuclear Mo-Pt and W-Pt Complexes
Organometallics, Vol. 18, No. 2, 1999 253
of 4 addition of H+ occurs also on the isonitrile bridge
or whether alternatively protonation of the metal-metal
bond or the metal centers leading to hydride complexes
is preferred, we reacted 4 with an excess of HBF4‚Et2O
at 253 K. After addition of the latter to a solution of 4
in dichloromethane, instantaneous N-protonation oc-
curs, leading exclusively to the yellow cationic µ-ami-
nocarbyne complexes [(OC)4M{µ-CN(H)CH2SO2p-tolyl}-
(µ-dppa)Pt(PPh3)][BF4], 5. These complexes may alterna-
tively be considered as dimetalated iminium salts, a
formalism that has been employed by A. R. Manning et
al. for the description of the bonding mode in the case
of homodinuclear compounds of the type [CpFe(CO)2(µ-
CNRR′)Fe(CO)2Cp]+.20 It seems that the stronger π-ac-
ceptor character of the µ-aminocarbyne ligand (com-
pared to a µ-CNR ligand) in addition to the positive
charge causes a significant stabilizing effect. Whereas
the neutral bimetallics 3 and 4 (e.g., 4a ) gradually
decompose in chlorinated solvents, the higher stability
of 5 permitted now the recording of 13C{1H} NMR
spectra. The resonance of the µ-carbyne carbon of 5b
was detected at δ 318.5 (dd, 2J (P-C) ) 9, 68 Hz),
together with three sets of doublets for terminal carbo-
nyl ligands at δ 195.2 (2 CO, 2J (P-C) ) 8 Hz), 197.5 (d,
1 CO, 2J (P-C) ) 15 Hz) and 199.3 (d, 1 CO, 2J (P-C) )
9 Hz). A broad doublet at δ 75.3 (4J (P-C) ) 15 Hz) was
assigned to the NCH2 carbon and a singlet at δ 21.6 to
the methyl group of the tosyl group. In the 195Pt NMR
spectra of 5, the protonation of the isonitrile bridge has
a marked influence on the chemical shifts of the ddd
resonances, which are shifted to ca. 290 ppm to lower
field (5a , δ -2392; 5b, δ -2385) compared to the
precursors 4.
Sch em e 2
stream of SO2 for 5 min. IR monitoring of the reaction
after 10 min revealed the complete disappearance of 4a
and the formation of several new complexes. We suggest
the initial formation of a species of the type [(OC)3-
(CNCH2SO2p-tolyl)Mo(µ-SO2)(µ-dppa)Pt(Ph3)] having a
terminal bound isonitrile ligand, since a ν(CN) stretch
was observed at 2119 cm-1. However, layering a con-
centrated solution of the reaction mixture with hexane
afforded after 3 days in 44% yield orange crystals of the
sulfur dioxide-bridged complex [(OC)4Mo(µ-SO2)(µ-dppa)-
Pt(PPh3)]‚OdPPh3 7a , which has surprisingly lost the
isonitrile ligand (Scheme 2). 31P NMR spectroscopy,
elemental analysis, and an X-ray diffraction study
revealed (see below) that additionally a triphenylphos-
phine oxide molecule interacts via a hydrogen bridge
with the N-H group of the dppa ligand. This may be
explained by partial decomposition/oxidation during the
crystallization. This complex was alternatively prepared
in improved yields (79%) by reaction of the µ-CO
complex 3a with SO2 under selective substitution of the
bridging CO ligand (Scheme 2) and subsequent addition
of a stoichiometric amount of OdPPh3. For comparison,
the W-Pt complex [(OC)4W(µ-SO2)(µ-dppa)Pt(PPh3)], 7b
was prepared also in an analogous manner. Infrared
monitoring of the course of the reaction showed quan-
titative conversion after 10 min under gentle SO2 purge.
Precipitation with hexane yielded 7b as an analytically
pure yellow powder, which remained unchanged even
after exposure to air for several hours. We assign two
vibrations of medium intensity at 1183 and 1044 cm-1
(KBr), absent in the IR spectrum of [(OC)4W(µ-CO)(µ-
dppa)Pt(PPh3)], 3b, to the ν(SO) frequencies of the
bridging sulfur dioxide ligand. This region seems, ac-
cording to previous studies of Kubas, to be very char-
acteristic for a µ-SO2 bonding mode.21 For example,
almost identical ν(SO) values (1186 and 1048 cm-1) have
Syn th esis of Ison itr ile-Su bstitu ted µ-Am in oca r -
byn e Com p lexes. Stoichiometric addition of 2,6-xylyl
isonitrile or benzyl isonitrile to 5b leads to selective
substitution of a carbonyl ligand to yield the stable
µ-aminocarbyne complexes [(OC)3(RNC)W{µ-CN(H)CH2-
SO2p-tolyl}(µ-dppa)Pt(PPh3)][BF4] (6a , R ) 2,6-xylyl;
6b, R ) benzyl), which have also been fully character-
ized by elemental analysis, FAB+ mass spectrometry,
multinuclear NMR, and IR spectroscopies. In addition
to the two carbonyl vibrations at 2018 (m) and 1938 (vs)
cm-1, a strong isonitrile absorption band is found at
2136 cm-1 in the IR spectrum of 6a ; a weak band at
1596 cm-1 is tentatively assigned to the ν(CN) band of
the aminocarbyne ligand. In the 13C{1H} NMR of 6a the
2
µ-carbyne resonance at δ 314.7 (ddd, J (P-C) ) 3, 6,
66 Hz) is somewhat high-field shifted compared to that
of 5b. The observation of two carbonyl signals at δ 200.6
(d, 1 CO, 2J (P-C) ) 20 Hz) and δ 198.6 (dd, 2 CO, 2J (P-
C) ) 2, 9 Hz), a broadened isonitrile resonance at δ
155.1 (d, 2J (P-C) ) 10 Hz) together with a broad
doublet (4J (P-C) ) 12 Hz) at δ 74.9, arising from the
NCH2 group, and two singlets at δ 21.6 and 18.2 in a
1:2 ratio further corroborate our structural proposal for
6a .
Syn th esis of Heter od in u clea r µ-SO2 Com p lexes.
To see whether the bridging bonding mode of the
µ-isonitrile ligand remains after addition of other ligands,
which are known to behave as strong π-acceptors, we
purged a dichloromethane solution of 4a under a gentle
(20) (a) Willis, S.; Manning, A. R.; Stephens, F. S. J . Chem. Soc.,
Dalton Trans. 1980, 186. (b) Cox, G.; Dowling, C.; Manning, A. R.;
McArdle, P.; Cunningham, D. J . Organomet. Chem., 1992, 438, 143.
(21) Kubas, G. J . Inorg. Chem. 1979, 18, 182.

254 Organometallics, Vol. 18, No. 2, 1999
Knorr and Strohmann
Ta ble 4. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for Com p lex 7a
Pt-Mo
2.9332(10)
2.2000(12)
2.2904(13)
2.3167(14)
2.502(14)
2.5308(17)
2.039(6)
2.007(5)
2.016(6)
2.049(9)
1.462(3)
1.472(3)
1.141(6)
1.137(6)
1.133(7)
1.684(4)
1.685(4)
1.487(4)
S-Pt-Mo
56.82(4)
47.24(3)
75.94(3)
111.24(5)
152.98(4)
75.27(4)
Pt-S
S-Mo-Pt
Pt-P(3)
Pt-P(2)
Mo-P(1)
Mo-S
Pt-S-Mo
P(1)-Mo-S
P(2)-Pt-S
P(1)-Mo-Pt
P(2)-Pt-Mo
P(3)-Pt-Mo
P(2)-Pt-P(3)
S-Mo-C(1)
S-Mo-C(2)
S-Mo-C(3)
S-Mo-C(4)
P(1)-Mo-C(1)
P(1)-Mo-C(2)
P(1)-Mo-C(3)
P(1)-Mo-C(4)
P(1)-N-P(2)
Mo-C(1)
Mo-C(2)
Mo-C(3)
Mo-C(4)
S-O(5)
97.40(4)
158.13(3)
104.47(5)
84.59(16)
78.21(16)
159.44(17)
102.13(16)
87.01(15)
170.44(15)
86.47(16)
88.79(15)
119.5(2)
S-O(6)
O(1)-C(1)
O(2)-C(2)
O(3)-C(3)
P(1)-N
P(2)-N
P(4)-O(7)
been reported for [(OC)2W(µ-CO)(µ-SO2)(µ-dppm)2-
RhCl].22d,23a
Cr yst a l St r u ct u r e of [(OC)4Mo(µ-SO2)(µ-d p p a )-
P t(P P h 3)]‚OdP P h 3 (7a ). Several examples of heterodi-
F igu r e 5. View of the crystal structure of [(OC)4Mo(µ-
SO2)(µ-dppa)Pt(PPh3)]‚OdPPh3 (7a ) with the atom-num-
bering scheme.
nuclear µ-SO2 complexes have been reported during the
22
past decade.
However, only two of them have been
crystallographically studied very recently. The two
examples possessing a metal-metal bond are [(OC)2Mo-
(µ-CO)(µ-SO2)(µ-dppm)2RhCl] and [Cp*Ni(µ-SO2)(µ-
CO)W(MeCp)] prepared by Lorenz’s and Chetcuti’s
groups, respectively.23 We therefore determined the
structure of 7a by an X-ray diffraction study. Suitable
crystals of 7a containing two molecules of CH2Cl2 and
a hydrogen-bound OdPPh3 molecule were obtained from
a concentrated CH2Cl2 solution layered with hexane.
The separation of the two metal centers (2.933(1) Å)
(Table 4) is significantly longer compared to that of 4b,
but falls still in the range observed for other Mo-Pt
complexes containing a metal-metal bond. Mo-Pt
distances of 2.912(4), 2.957(3), and 2.958(1) Å have been
determined for [MeCp(OC)2Mo(µ-dppm)Pt(dppm)]+, the
tetranuclear chain complex [CpMoPt(H)(µ-PPh2)2(CO)2]2,
and the cluster [MoRhPt(µ-CO)2(µ-PPh2)(σ,η2-C6H5)-
(PPh3)(Cp)], respectively.24 The overall geometry and
ligand arrangement around the Mo center is reminis-
cent of 4b and may be considered as distorted octahedral
with an additional metal-metal bond bisecting the
angle between C(4) and the sulfur atom [C(4)-Mo-S
102.1(2)°, C(4)-Mo-Pt 71.7(2)°, S-Mo-Pt 47.24(3)°].
The Pt atom is present in a distorted square planar
environment (the rms deviation from the plane defined
by Pt, Mo, P(2), P(3), and S being only 0.085 Å), thus
conferring an 18-electron configuration for the Mo center
and a 16-electron configuration for the Pt0 center. The
coordination polyhedra of the two metal fragments are
again mutually inclined, which is manifested in the
torsion angle P(1)-Mo-Pt-P(2) of 32.39° between the
two dppa-phosphorus atoms. In addition to the spanning
by the dppa backbone forming a five-membered ring,
the two metal centers are asymmetrically bridged by a
µ-SO2 ligand via its sulfur atom. The Mo-S bond length
of 2.531(2) Å is significantly longer than the Pt-S bond
length of 2.220(1) Å. For comparison, a Mo-S bond
length of 2.386(7) Å has been reported for [(OC)2Mo(µ-
CO)(µ-SO2)(µ-dppm)2RhCl].23a The Pt-S distance is in
the typical range found for SO2-bridged platinum clus-
ters.25 In contrast to [(OC)2Mo(µ-CO)(µ-SO2)(µ-dppm)2-
RhCl], where somewhat different S-O distances [1.51(2)
and (1.46(2) Å] have been observed, those of 7a are
almost identical (1.462(3) and 1.472(3) Å) (Figure 5).
Con clu sion
We have shown that heterobimetallic dppa-bridged
Mo-Pt and W-Pt complexes [(OC)4M(µ-CO)(µ-dppa)-
Pt(PPh3)] are easy accessible by reaction of the metal-
lophosphines [(OC)5M(η1-dppa)] with [Pt(C2H4)(PPh3)2].
The reactivity of these µ-CO complexes toward various
isonitriles has been investigated. Heterobimetallic µ-CNR
complexes [(OC)4M(µ-CdNR)(µ-dppa)Pt(PPh3)] possess-
ing an asymmetric isonitrile bridge can be obtained by
selective substitution of a µ-CO ligand, if the incoming
isonitrile behaves as a good π-acceptor. In the case of
more electron-donating isonitriles, a terminal coordina-
tion of the CNR ligand is preferred to yield the very
labile substitution products [(OC)3(RNtC)M(µ-CO)(µ-
dppa)Pt(PPh3)]. We are currently investigating the
reactivity of [(OC)4M(µ-CO)(µ-Ph2PXPPh2)Pt(PR3)] and
[(OC)3Fe(µ-CO)(µ-Ph2PXPPh2)Pt(PR3)] (X ) NH, CH2)
toward other isonitriles possessing good π-acceptor
properties to extend the still very limited number of
(22) (a) Pringle, P. G.; Shaw, B. L. J . Chem. Soc., Dalton Trans.
1983, 889. (b) Schenk, W. A. Z. Naturforsch. 1986, 41b 663. (b) Ho¨rlein,
R.; Herrmann, W. A.; Barnes, C. E.; Weber, C. E.; Kru¨ger, C.; Ziegler,
M. L.; Zahn, T. J . Organomet. Chem. 1987, 321, 257. (c) Schenk, W.
A.; Hilpert, G. H. J . Chem. Ber. 1989, 122, 1623. (d) Schenk, W. A.;
Hilpert, G. H. J . Chem. Ber. 1991, 124, 433. (e) Heyke, O.; Beuter, G.;
Lorentz, I.-P. Z. Naturforsch. 1992, 47B, 668. (f) Antwi-Nsiah, F. H.;
Oke, O.; Cowie, M. Organometallics 1996, 15, 1042.
(23) (a) Heyke, O.; Hiller, W.; Lorentz, I.-P. Chem. Ber. 1991, 124,
2217. (b) Bartlone, A. F.; Chetcuti, M. J .; Navarro, R., III; Shang, M.
Inorg. Chem. 1995, 34, 980.
(24) (a) Braunstein, P.; de Bellefon, C.; Lanfranchi, M.; Tiripicchio,
A. Organometallics 1984, 3, 1772. (b) Blum, T.; Braunstein, P.;
Tiripicchio, A.; Tiripicchio Camellini, M. Organometallics 1984, 3, 1772.
(c) Farrugia, L. J .; Miles, A. D.; Stone, F. G. A. J . Chem. Soc., Dalton
Trans. 1984, 2415.
(25) (a) Moody, D. C.; Ryan, R. R. Inorg. Chem. 1977, 16, 1052. (b)
Hallam, M. F.; Howells, N. D.; Mingos, D. M. P.; Wardle, R. W. M. J .
Chem. Soc., Dalton Trans. 1985, 845.

Dinuclear Mo-Pt and W-Pt Complexes
Organometallics, Vol. 18, No. 2, 1999 255
Ta ble 5. Su m m a r y of Cr ysta l Da ta , In ten sity Mea su r em en ts, a n d Refin em en t of 1a a n d 2a
1a
2a
empirical formula
formula mass, g mol-1
collection T, K
λ(Mo KR), pm
cryst syst
space group
a, pm
b, pm
c, pm
C
31H25MoN2O5P2
C30H24MoN2O4P2
634.39
293(2)
71.073
monoclinic
P21/n
1111.1(14)
1452.3(14)
1863(2)
90
104.3(2)
90
2.913(5)
4
1.446
663.41
293(2)
71.073
triclinic
P1h
1104.5(12)
1213.0(12)
1221.2(12)
94.60(13)
104.03(13)
92.11(13)
1.580(3)
2
R, deg
â, deg
γ, deg
V, pm3
Z
D(calcd), g cm-3
µ, mm-1
1.395
0.556
674
0.597
1288
F(000)
cryst dimens, mm
diffractometer
θ range, deg
0.60 × 0.30 × 0.30
Siemens Stoe AED 2
1.69-22.50
-11/11, -13/13, 0/13
4122
4122
3833
0/375
1.101
0.50 × 0.40 × 0.30
Siemens Stoe AED 2
1.80-22.50
-11/11, 0/15, 0/20
3806
3806
3337
0/357
1.107
index ranges (-h/h, -k/k, -l/l)
no. of reflns colled
no. of indep reflns
no. of obs reflns [I > 2σ(I)]
no. of restraints/params
goodness of fit
R1a [I > 2σ(I)]
wR2b(all data)
max/min res electron dens, e nm-3
0.0272
0.0698
290/-430
0.0259
0.0681
230/-290
R1 ) ∑||Fo| - |Fc||/∑|Fo|. wR2 ) {∑[w(Fo - Fc2)2]/∑[w(Fo2)2]}0.5
.
a
b
2
Ta ble 6. Su m m a r y of Cr ysta l Da ta , In ten sity Mea su r em en ts, a n d Refin em en t of 4b a n d 7a
4b
7a
empirical formula
formula mass, g mol-1
collection T, K
λ(Mo KR), pm
cryst syst
space group
a, pm
b, pm
c, pm
C
60H57N2O6P3PtS W
C66H55Cl4MoNO7P4PtS
1562.88
293(2)
71.073
triclinic
1405.99
293(2)
71.073
orthorhombic
Pbca
2055.0(13)
2209.8(14)
2605(2)
90
P1h
1254.4(3)
1457.5(3)
1920.0(4)
99.78(3)
R, deg
â, deg
90
90
98.99(3)
γ, deg
103.00(3)
3.3008(12)
2
1.572
2.649
V, pm3
11.830(13)
8
1.579
4.472
5536
Z
D(calcd), g cm-3
µ, mm-1
F(000)
1556
cryst dimens, mm
diffractometer
θ range, deg
0.40 × 0.30 × 0.20
Siemens Stoe AED 2
1.56-22.50
0/12, 0/23, 0/28
5575
5575
4500
0/649
1.170
0.50 × 0.40 × 0.30
Siemens Stoe AED 2
1.64-25.07
-14/14, -17/17, 0/22
11 217
11 217
10374
0/771
1.076
index ranges (-h/h, -k/k, -l/l)
no. of reflns colled
no. of indep reflns
no. of obs reflns [I > 2σ(I)]
no. of restraints/params
goodness of fit
R1a [I > 2σ(I)]
wR2b (all data)
max/min res electron dens, e nm-3
0.0399
0.1107
940/-580
0.0343
0.0921
1655/-1725
R1 ) ∑||Fo| - |Fc||/∑ | Fo |. wR2 ) {∑[w(Fo - Fc2)2]/ ∑[w(Fo2)2]}0.5
.
a
b
2
romethane was distilled from P4O10. Nitrogen was passed
through BASF R3-11 catalyst and molecular sieve columns to
remove residual oxygen or water. Elemental C, H, and N
analyses were performed on a Leco Elemental Analyzer CHN
900. The 1H, 31P{1H}, and 13C{1H} NMR spectra were recorded
at 200.13, 81.01, and 50.32 MHz, respectively, on a Bruker
ACP 200 instrument. Phosphorus chemical shifts were refer-
enced to 85% H3PO4 in H2O with downfield shifts reported as
positive. 195Pt chemical shifts were measured on a Bruker ACP
heterobimetallic µ-CNR complexes to further study their
chemical reactivity and structural aspects in the crys-
talline state.
Exp er im en ta l Section
All reactions were performed in Schlenk-tube flasks under
purified nitrogen. Solvents were dried and distilled under
nitrogen before use, toluene and hexane over sodium. Dichlo-

256 Organometallics, Vol. 18, No. 2, 1999
Knorr and Strohmann
200 instrument (42.95 MHz) and externally referenced to K2-
PtCl4 in water with downfield chemical shifts reported as
positive. The numbering of the phosphorus nuclei in the 31P
NMR spectra corresponds to the numbering used in the single-
crystal X-ray determinations. NMR spectra were recorded in
pure CDCl3, unless otherwise stated. The presence and amount
of toluene of solvation in 3a ,b and of CH2Cl2 in 5a ,b have been
determined from the 1H NMR spectrum. The reactions were
generally monitored by IR spectroscopy in the ν(CO) region.
Tosylmethyl isonitrile, benzyl isonitrile, and 2,6-xylyl isonitrile
were obtained from Aldrich and Fluka and used as received.
Dppa was prepared as described by Meinel and No¨th.13
[(OC)4W(µ-CO)(µ-d p p a )P t(P P h 3)] (3b). This complex was
prepared as decribed for 3a . Yield: 0.982 g, 81%. Anal.
Found: C, 49.68; H, 3.41; N, 1.25. Calcd for C47H36NO5P3PtW‚
0.5C7H8 (M ) 1166.66 + 46.03): C, 50.02; H, 3.33; N, 1.16. IR
(CH2Cl2): ν(NH), 3318 w; ν(CO), 2018 s, 1908 vs, br, 1791 m,
br cm-1; NMR: 1H, δ 5.37 (dt, br, 1H, NH, 2J (P-H) ) 9, 4J (P-
3
H) ) 4, J (Pt-H) ) 106 Hz), 6.82-7.49 (m, 35H, C6H5); 31P-
{1H}, δ 79.1 (dd, P2(Pt), 2+3J (P1-P2) ) 166, 2J (P2-P3) ) 73,
1J (P-Pt) ) 3734 Hz), 65.2 (dd, P1(W), 2+3J (P1-P2) ) 166,
1
3+4J (P1-P3) ) 28, 2+3J (Pt-P) ) 63 Hz, J (P-W) ) 167), 44.8
(dd, P3(Pt), 2J (P2-P3) ) 73, 3+4J (P1-P3) ) 28, 1J (P-Pt) ) 4199
Hz); 195Pt{1H}, δ -2656 (ddd, 1J (Pt-P) ) 4199, 3734, 2+3J (Pt-
P) ) 63 Hz).
[(OC)5Mo(η1-d p p a )] (1a ). Me3NO (0.751 g, 10.0 mmol) was
added to a suspension of Mo(CO)6 (2.64 g, 10.0 mmol) in 150
mL of MeCN. After stirring for 30 min, dppa (3.853 g, 10 mmol)
was added to the clear yellow solution. The mixture was stirred
for 3 h. The crude product containing ca. 10% of 2a crystallized
in a refrigerator at 5 °C. Suitable crystals for X-ray crystal-
lography were separated manually. A second crop of pure 1a ‚
MeCN was precipitated as a colorless powder by addition of
hexane to the mother liquor. After drying in vacuo for several
hours the coordinated acetonitrile was removed. Overall
yield: 5.34 g, 86%. Anal. Found: C, 55.50; H, 3.65; N, 2.32.
Calcd for C29H21NO5P2Mo (M ) 621.38): C, 56.05; H, 3.41; N,
2.25. IR (CH2Cl2) ν(CO): 2072 s, 1991 w, 1946 vs cm-1. NMR:
1H (298 K), δ 1.96 (s, 3H, MeCN), 3.86 (“t”, br, 1H, NH, 2J (P-H
) 7.1 Hz), 7.24-7.64 (m, 20H, phenyl); 31P{1H}, δ 83.9 (d, P1-
[(OC)4Mo(µ-CNCH2SO2p-tolyl)(µ-d p p a )P t(P P h 3)] (4a ).
Solid p-tosylmethyl isonitrile (0.098 g, 0.50 mmol) was added
to a solution of 3a (0.585 g, 0.50 mmol) in 15 mL of CH2Cl2.
After being stirred for 30 min, the solution was concentrated
to ca. 10 mL, layered with pentane (ca. 10 mL), and stored at
-25 °C. Yellow microcrystals of 4a were formed, which were
collected after 2 days and dried in vacuo. Yield: 0.392 g, 63%.
Anal. Found: C, 53.36; H, 4.09; N, 2.35. Calcd for C55H45N2-
MoO6P3PtS (M ) 1245.98): C, 53.01; H, 3.64; N, 2.25. IR (CH2-
Cl2): ν(CO), 2022 s, 1914 vs, br, 1890 sh; ν(CdN), 1677 m, br
3
cm-1. NMR: 1H, δ 4.89 (m, br, 1H, NH, J (Pt-H) ) 108 Hz),
6.89-7.69 (m, 35H, C6H5); 31P{1H}, δ 83.9 (dd, P1(Mo), 2+3J (P1-
P2) ) 131, 3+4J (P1-P3) ) 36, 2+3J (Pt-P) ) 59 Hz), 72.4 (dd,
P2(Pt), 2+3J (P1-P2) ) 131, 2J (P2-P3) ) 57, 1J (P-Pt) ) 3307
Hz), 41.8 (dd, P3(Pt), 2J (P2-P3) ) 57, 3+4J (P1-P3) ) 36, 1J (P-
Pt) ) 4481 Hz); 195Pt{1H}, δ -2671 (ddd, 1J (Pt-P) ) 4481,
3307, 2+3J (Pt-P) ) 59 Hz).
2
(Mo), J (P1-P2) ) 65 Hz), 32.9 (d, P2(uncoordinated).
[(OC)5W(η1-d p p a )]‚MeCN (1b). Me3NO (0.751 g, 10.0
mmol) was added to a suspension of W(CO)6 (3.51 g, 10.0
mmol) in a mixture of 100 mL of MeCN/50 mL of toluene. After
stirring for 2 h, dppa (3.853 g, 10 mmol) was added to the clear
yellow solution. The mixture was heated at 60 °C for 2 days.
After filtration of some insoluble material a mixture of green-
yellow 2b‚MeCN (80%) and nearly colorless 1b‚MeCN (20%)
(31P NMR integration) cocrystallized at 5 °C. A second crop of
[(OC)4W(µ-CNCH 2SO2p -t olyl)(µ-d p p a )P t (P P h 3)] (4b ).
Solid p-tosylmethyl isonitrile (0.098 g, 0.50 mmol) was added
to a solution of 3b (0.606 g, 0.50 mmol) in 10 mL of CH2Cl2.
After being stirred for 30 min, the solution was layered with
pentane (ca. 15 mL) and stored at 5 °C in a refrigerator.
Orange-red crystals of 4b were formed, which were collected
after 2 days. Yield: 0.349 g, 84%. Anal. Found: C, 51.40; H,
4.09; N, 2.04. Calcd for C55H45N2O6P3PtSW‚C5H12 (M ) 1333.90
+ 72.09): C, 51.25; H, 4.09; N, 1.99. IR (CH2Cl2): ν(NH), 3319
w; ν(CO), 2015 s, 1908 vs, br; ν(CdN), 1669 m cm-1. NMR:
1H, δ 2.26 (s, 3H, tolyl-CH3), 4.86 (s, br, NCH2), 5.32 (dt, br,
1H, NH, 2J (P-H) ) 8, 4J (P-H) ) 4, 3J (Pt-H) ) 88 Hz), 6.61-
7.56 (m, 39H, phenyl); 31P{1H}, δ 71.2 (dd, P2(Pt), 2+3J (P1-P2)
a
mixture of 2b‚MeCN (15%) and 1b‚MeCN (85%) was
obtained after layering the mother liquor with hexane. Pure
1b‚MeCN was isolated by separation of the resulting crystals
by hand. Anal. Found: C, 50.14; H, 3.44; N, 3.72. Calcd for
C29H21NO5P2W‚MeCN (M ) 709.29 + 41.05): C, 49.63, H, 3.22;
N, 3.74. IR (CH2Cl2) ν(CO): 2071 s, 1980 w, 1937 vs cm-1
.
NMR: 1H (298 K), δ 1.94 (s, 3H, MeCN), 3.33 (“t”, br (not
resolved dd), 1H, NH), 7.11-7.54 (m, 20H, phenyl); 31P{1H},
δ 63.7 (d, P1(W), 2J (P1-P2) ) 59 Hz, 1J (P-W) 192 Hz), 32.7
(d, P2(uncoordinated).
2
1
) 134, J (P2-P3) ) 56, J (P-Pt) ) 3253 Hz), 58.1 (dd, P1(W),
2+3J (P1-P2) ) 134, 3+4J (P1-P3) ) 38, 2+3J (Pt-P) ) 49, J (P-
1
W) ) 219 Hz), 43.7 (dd, P3(Pt), J (P2-P3) ) 56, 3+4J (P1-P3) )
2
39, J (P-Pt) ) 4448 Hz); 195Pt{1H}, δ -2682 (ddd, J (Pt-P)
1
1
[(OC)4Mo(µ-CO)(µ-dppa)P t(P P h 3)] (3a). [Pt(C2H4)(PPh3)2]
(0.748 g, 1.0 mmol) was added to a solution of 1a (0.621 g, 1
mmol) in toluene (10 mL). Ethylene evolution was observed
and the solution turned rapidly to yellow-orange. After 15 min
precipitation of the bright yellow product occurred, which was
completed by slow concentration of the solution under reduced
pressure and subsequent addition of hexane (10 mL). The
product was filtered off, rinsed with hexane, and dried under
vacuum. 31P NMR spectroscopy revealed that the crude
product was contaminated with ca. 10% of the chelate complex
[(OC)4Mo(dppa)], 2a . A second crop of analytically pure 3a was
obtained from the mother liquor after 3 days at 4 °C in the
form of yellow microcystals, which contained one molecule of
toluene of solvation. Overall yield: 0.954 g, 82%. Anal.
Found: C, 54.98; H, 3.54; N, 1.45. Calcd for C47H36NO5P3PtMo‚
C7H8 (M ) 1078.75 + 92.06): C, 55.39; H, 3.79.; N, 1.20. IR
(KBr): ν(NH), 3320 w; (CH2Cl2) ν(CO), 2021 s, 1914 vs, br,
1890 sh, 1805 m, br cm-1. NMR: 1H, δ 4.89 (m, br, 1H, NH,
3J (Pt-H) ) 105 Hz), 6.89-7.69 (m, 35H, C6H5); 31P{1H}, δ 89.1
(dd, P1(Mo), 2+3J (P1-P2) ) 157, 3+4J (P1-P3) ) 25, 2+3J (Pt-P)
) 4448, 3253, 2+3J (Pt-P) ) 49 Hz).
[(OC)4Mo(µ-CN(H )CH 2SO2p -t olyl)(µ-d p p a )P t (P P h 3)]-
[BF 4] (5a ). This complex was prepared by addition of an excess
of HBF4‚Et2O at 253 K to a solution of 4a (0.125 g, 0.1 mmol)
in CH2Cl2 (10 mL). After warming all volatiles were removed
under reduced pressure. The orange-red residue was rinsed
with Et2O (3 mL) and dried again in vacuo. Yield: 0.104 g,
76%. Anal. Found: C, 48.13; H, 3.53; N, 1.94. Calcd for C55H46
-
BF4MoN2O6P3PtS‚0.5CH2Cl2 (M ) 1333.80 + 42.46): C, 48.47;
H, 3.37; N, 2.04. IR (CH2Cl2): ν(CO), 2054 s, 2006 m, 1957 vs,
br; ν(C-N), 1519 w cm-1. NMR: 1H, δ 2.39 (s, 3H, tolyl-CH3),
4.89 (d, br, NCH2, 4J (P-H) ) 5.9 Hz), 6.11 (m, br, 1H, NH,
3J (Pt-H) ) 74 Hz), 6.51-7.64 (m, 39H, phenyl), 8.01 (m, br,
1H, CNH); 31P{1H}, δ 81.6 (dd, P1(Mo), 2+3J (P1-P2) ) 81,
3+4J (P1-P3) ) 28, 2+3J (Pt-P) ) 132 Hz), 62.2 (dd, P2(Pt),
2
1
2+3J (P1-P2) ) 81, J (P2-P3) ) 12, J (P-Pt) ) 2792 Hz), 38.6
(dd, P3(Pt), 2J (P2-P3) ) 12, 3+4J (P1-P3) ) 28, 1J (P-Pt) ) 4086
Hz); 195Pt{1H} (258 K), δ -2392 (ddd, J (Pt-P) ) 4112, 2790,
1
2+3J (Pt-P) ) 132 Hz). 13C{1H} NMR: δ 22.0 (s, tolyl-CH3),
75.1 (d, br, N-CH2, 4J (P-C) ) 11 Hz), 127.5-146.1 (m,
2
) 69 Hz), 79.9 (dd, P2(Pt), 2+3J (P1-P2) ) 157, J (P2-P3) ) 75,
1J (P-Pt) ) 3879 Hz), 42.8 (dd, P3(Pt), 2J (P2-P3) ) 75, 3+4J (P1-
P3) ) 25, 1J (P-Pt) ) 4089 Hz); 195Pt{1H}, δ -2676 (ddd, 1J (Pt-
P) ) 4089, 3878, 2+3J (Pt-P) ) 69 Hz).
aromatic C), 204.3 (d, 2 CO, J (P-C) ) 9 Hz), 207.5 (d, 1 CO,
2
2J (P-C) ) 11 Hz), 208.1 (d, 1 CO, 2J (P-C) ) 18 Hz), 321.9
2
(dd, µ-C, J (P-C) ) 10, 66 Hz).

Dinuclear Mo-Pt and W-Pt Complexes
Organometallics, Vol. 18, No. 2, 1999 257
[(OC)4W(µ-CN(H )CH 2SO2p -t olyl)(µ-d p p a )P t (P P h 3)]-
[BF 4] (5b). This orange-yellow complex was prepared in
quantitative yield as described for 5a . Anal. Found: C, 44.78;
H, 3.47; N, 1.93. Calcd for C55H46BF4N2O6P3PtSW‚CH2Cl2 (M
) 1421.71 + 84.94): C, 44.64; H, 3.21; N, 1.86. IR (CH2Cl2):
(ca. 10 mL), and stored at -25 °C. Yellow-orange microcrystals
of 7a ‚Ph3PdO were formed, which were collected after 2 days
and dried in vacuo for 12 h to remove the solvated dichlo-
romethane. Yield: 0.550 g, 79%. Anal. Found: C, 54.86; H,
3.49; N, 0.97. Calcd for C64H51NMoO7P4PtS (M ) 1393.10): C,
55.18; H, 3.69; N, 1.00. IR (KBr): ν(CO), 2032 s, 1927 vs, br;
ν(SO), 1180 m, 1043 m cm-1. NMR: 1H, δ 5.71 (m, br, 1H,
ν(CO), 2052 s, 2001 m, 1951 vs, br; ν(C-N), 1515 m cm-1
.
NMR: 1H, δ 2.41 (s, 3H, tolyl-CH3), 4.86 (d, br, NCH2, 4J (P-
H) ) 7.9 Hz), 6.82 (m, br, 1H, NH), 6.57-7.55 (m, 39H, phenyl),
7.83 (m, br, 1H, CNH); 31P{1H}, δ 59.6 (dd, P2(Pt), 2+3J (P1-
P2) ) 72, 2J (P2-P3) ) 6, 1J (P-Pt) ) 2767 Hz), 52.5 (dd, P1-
(W), 2+3J (P1-P2) ) 72, 3+4J (P1-P3) ) 23, 2+3J (Pt-P) ) 97 Hz,
3
NH, J (Pt-H) ) 119 Hz), 6.89-7.69 (m, 50H, C6H5); 31P{1H},
δ 86.2 (dd, P1(Mo), 2+3J (P1-P2) ) 123, 3+4J (P1-P3) ) 26,
2+3J (Pt-P) ) 24 Hz), 66.9 (dd, P2(Pt), 2+3J (P1-P2) ) 123,
2J (P2-P3) ) 36 1J (P-Pt) ) 3745 Hz), 29.3 (s, Ph3PO), 27.4
(dd, P3(Pt), 2J (P2-P3) ) 36, 3+4J (P1-P3) ) 26, 1J (P-Pt) ) 4551
Hz).
2
1J (P-W) ) 222 Hz), 40.0 (dd, P3(Pt), J (P2-P3) ) 6, 3+4J (P1-
P3) ) 23, 1J (P-Pt) ) 4217 Hz); 195Pt{1H}; δ -2385 (ddd, 1J (Pt-
P) ) 4217, 2767, 2+3J (Pt-P) ) 97 Hz). 13C{1H} NMR: δ 21.6
(s, tolyl-CH3), 75.3 (d, br, N-CH2, 4J (P-C) ) 15 Hz), 128.
1-146.6 (m, aromatic C), 195.2 (d, 2 CO, 2J (P-C) ) 8 Hz),
[(OC)4W(µ-SO2)(µ-d p p a )P t(P P h 3)] (7b). A solution of 3b
(0.606 g, 0.50 mmol) in 10 mL of CH2Cl2 in 10 mL of CH2Cl2
was purged with a slow stream of SO2 for 10 min. After stirring
for 20 min. the solution was concentrated to ca. 10 mL, layered
with hexane (ca. 10 mL), and stored at -25 °C. Yellow-orange
microcrystals of 7b were formed, which were collected after 2
days and dried in vacuo for 10 h. Yield: 0.433 g, 72%. Anal.
Found: C, 46.40; H, 3.46; N, 1.45. Calcd for C46H36NO6P3PtWS
(M ) 1202.72): C, 45.94; H, 3.02; N, 1.17. IR (CH2Cl2): ν(CO),
2043 s, 1956 sh, 1942 vs cm-1. NMR: 1H, δ 5.71 (m, br, 1H,
2
2
197.5 (d, 1 CO, J (P-C) ) 15 Hz), 199.3 (d, 1 CO, J (P-C) )
2
9 Hz), 318.5 (dd, µ-C, J (P-C) ) 9, 68 Hz).
[(OC)3(xylylNC)W(µ-CN(H)CH2SO2p-tolyl)(µ-d p p a )P t-
(P P h 3)][BF 4] (6a ). This complex was prepared by addition of
2,6-xylylNC (0.131 g, 0.1 mmol) to a solution of 5b (0.151 g,
0.1 mmol) in CH2Cl2 (9 mL). After stirring for 3 h, the volume
was reduced to ca. 5 mL and the solution layered with Et2O.
After 2 days in a refrigerator yellow-orange crystals were
formed, which were dried in vacuo for several hours. Yield:
0.10 g, 69%. Anal. Found: C, 49.76; H, 3.88; N, 2.68. Calcd
for C63H55BF4N3O5P3PtSW (M ) 1524.87): C, 49.62; H, 3.64;
N, 2.75. IR (CH2Cl2): ν(CN), 2136 s; ν(CO), 2018 m, 1938 vs;
ν(CdN), 1596 w cm-1. NMR: 1H, δ 1.99 (s, 6H xylyl-CH3),
3
NH, J (Pt-H) ) 119 Hz), 6.89-7.69 (m, 50H, C6H5); 31P{1H},
2
1
δ 67.4 (dd, P2(Pt), 2+3J (P1-P2) ) 130, J (P2-P3) ) 32, J (P-
Pt) ) 3712 Hz), 59.1 (dd, P1(W), 2+3J (P1-P2) ) 130, 3+4J (P1-
P3) ) 26, 2+3J (Pt-P) ) 4 Hz), 28.3 (dd, P3(Pt), 2J (P2-P3) ) 32,
3+4J (P1-P3) ) 26, J (P-Pt) ) 4307 Hz).
1
X-r a y Cr ysta l Str u ctu r e Deter m in a tion s. The crystals
were placed in a glass capillary and then mounted on a
Siemens Stoe AED2 diffractometer. Cell parameters were
obtained from least-squares fits to the settings of 25 reflections
in the range 5° < 2θ < 25°. No significant deviations in
intensity were registered for three monitored reflections
recorded at regular intervals. An empirical absorption correc-
tion was applied by ψ-scans. The structure was solved by direct
methods.26 The positions of all non-hydrogen atoms were
refined anisotropically.27 A riding model was employed for the
refinement of the CH hydrogen atom positions. The positions
of the NH hydrogen atoms were localized in difference Fourier
syntheses and refined freely. In 4b a phenyl group bonded to
P(2), the p-tolyl group, and a pentane molecule were found to
be disordered. Crystallographic details are given in Tables 5
and 6.
4
2.40 (s, 3H, tolyl-CH3), 4.84 (d, br, 2H, NCH2, J (P-H) ) 6.2
3
Hz), 6. 44 (m, br, 1H, NH, J (Pt-H) ) 84 Hz), 6.53-7.60 (m,
39H, phenyl), (CNH not observed); 31P{1H}, δ 61.8 (dd, P2(Pt),
2
1
2+3J (P1-P2) ) 79, J (P2-P3) ) 11, J (P-Pt) ) 2869 Hz), 58.3
(dd, P1(W), 2+3J (P1-P2) ) 79, 3+4J (P1-P3) ) 31, 2+3J (Pt-P) )
144 Hz), 39.8 (dd, P3(Pt), 2J (P2-P3) ) 11, 3+4J (P1-P3) ) 31,
1J (P-Pt) ) 3954 Hz); 195Pt{1H}, δ -2459 (ddd, 1J (Pt-P) )
3954, 2869, 2+3J (Pt-P) ) 144 Hz). 13C{1H} NMR: δ 18.2 (s,
4
xylyl-CH3), 21.6 (s, tolyl-CH3), 74.9 (d, br, N-CH2, J (P-C)
2
) 12 Hz), 127.9-147.2 (m, aromatic C), 155.1 (d, CN, J (P-
2
C) ) 10 Hz), 198.6 (dd, 2 CO, J (P-C) ) 2, 9 Hz), 200.6 (d, 1
CO, 2J (P-C) ) 20 Hz), 314.7 (ddd, µ-C, 2J (P-C) ) 3, 6, 66
Hz).
[(OC)3(b en zylNC)W(µ-CN(H )CH 2SO2p -t olyl)(µ-d p p a )-
P t(P P h 3)][BF 4] (6b). This complex was prepared as described
for 6a . Due to the formation of some Ph3PdO during attempts
to obtain single crystals, no satisfactory elemental analysis
could be obtained. The FAB+ mass spectrum (NBA matrix)
displays an intense peak for the cationic fragment at m/z 1424
(55%), whose simulated isotopic distribution is in agreement
with the experimental pattern. IR (CH2Cl2): ν(CN), 2156 m,
ν(CO) 2020 m, 1939 vs; ν(CdN), 1598 w cm-1. NMR: 1H, δ
2.46 (s, 3H, tolyl-CH3), 4, 39 (s,br, 2H, benzyl-CH2), 4.84 (d,
br, 2H, NCH2, 4J (P-H) ) 6.1 Hz), 6. 41 (m, br, 1H, NH, 3J (Pt-
H) ) 89 Hz), 6.53-7.60 (m, 44H, phenyl), (CNH not observed);
Ack n ow led gm en t. The Deutsche Forschungsge-
meinschaft is gratefully thanked for habilitation grants
and financial support to M.K. and C.S. and the DE-
GUSSA AG for a generous gift of Pt salts. M.K. is also
indebted to Prof. M. Veith and Dr. P. Braunstein for
their support and for providing the institute facilities
and to Dr. V. Huch for collection of the X-ray data sets.
Su p p or tin g In for m a tion Ava ila ble: ORTEP drawings,
tables of final atomic coordinates, tables of hydrogen atom
coordinates, thermal parameters for the non-hydrogen atoms,
and complete lists of bond distances and angles (40 pages).
Ordering information is given on any current masthead page.
2
31P{1H}, δ 61.1 (dd, P2(Pt), 2+3J (P1-P2) ) 81, J (P2-P3) ) 12,
1J (P-Pt) ) 2874 Hz), 58.1 (dd, P1(W), 2+3J (P1-P2) ) 81,
3+4J (P1-P3) ) 32, 2+3J (Pt-P) ) 147 Hz), 39.1 (dd, P3(Pt),
1
2J (P2-P3) ) 12, 3+4J (P1-P3) ) 32, J (P-Pt) ) 3908 Hz).
[(OC)4Mo(µ-SO2)(µ-d p p a )P t(P P h 3)]‚P h 3P dO (7a ). A so-
lution of 3a (0.585 g, 0.50 mmol) in 10 mL of CH2Cl2 was
purged with a slow stream of SO2 for 10 min. After stirring
for 15 min, an equimolar amount of Ph3PdO was added and
the solution concentrated to ca. 10 mL, layered with hexane
OM980756V
(26) Sheldrick, G. M. SHELXS-86, University of Go¨ttingen, Ger-
many, 1986.
(27) Sheldrick, G. M. SHELXL-93, University of Go¨ttingen, Ger-
many, 1993.