Synthesis of Pt(II)-Pt(II) and Pt/Pd(II)-Pt(0) monoalkynylphosphine bridging complexes

Article abstract of DOI:10.1021/om020374w

The monoalkynylphosphine complexes cis-[Pt(C₆F₅)₂(PPh₂C≡CR)(tht)] (R = Ph 1a, Tol 1b, tBu 1e, tht = tetrahydrothiophene) have been prepared by bridge splitting [{Pt(C₆F₅)₂(μ-tht)}₂] or by displacement of only one tht ligand from cis- [Pt(C₆F₅)₂(tht)₂] with PPh₂C≡CR. Complexes 1 react with cis- [Pt(C₆F₅)₂(thf)₂] to give binuclear derivatives [(C₆F₅)₂Pt(μ-tht)-(μ-1κP:2η ²-PPh₂C≡CR)Pt(C₆F₅)₂ ] (R = Ph 2a, Tol 2b, tBu 2c), containing a mixed tht/PPh₂C= CR bridging system. In contrast, treatment of 1 with [Pt(η²-C₂H₄)(PPh₃)₂] affords mixed-valence Pt(II)-Pt(0) complexes [{(C₆F₅)₂(tht)Pt(μ-1κP:2η² -PPh₂C≡CR)}Pt(PPh₃)₂] (R = Ph 3a, Tol 3b) stabilized by only one κP:η² bridging alkynyl phosphine. The molecular structures of 2a and 3a have been confirmed by single-crystal X-ray diffraction. Similarly, reactions of cis-bis(diphenylphosphino)alkyne complexes cis- [M(C₆F₅)₂(PPh₂C≡CR)₂ ] and cis-[Pt(C≡CR′)₂-(PPh₂C≡CR)₂] (M = Pt, Pd; R = Ph, Tol; R′ = Ph, tBu) with 1 or 2 equiv of [Pt(η²-C₂H₄)-(PPh₃)₂] yield the corresponding mixed-valence binuclear complexes cis-[{(C₆F₅)₂M(PPh₂C≡ CR)(μ-1-κP:2η²-PPh₂C≡CR)}Pt(PPh₃ )₂J (M = Pt, R = Ph 4a, Tol 4b; M = Pd, R = Ph 5a, Tol 5b) and cis-[{(C≡CR′)₂Pt(PPh₂C≡CR)(μ-1κ P:2η²-PPh₂C≡CR)}Pt(PPh₃)₂] (R′ = Ph, R = Ph 6a, Tol 6b; R′ = tBu, R = Ph 7a, Tol 7b), bearing only one PPh₂C≡CR η²-coordinated to a Pt(0)(PPh₃)₂ fragment.

Full text of DOI:10.1021/om020374w

Organometallics 2002, 21, 3733-3743
3733
Syn th esis of P t(II)-P t(II) a n d P t/P d (II)-P t(0)
Mon oa lk yn ylp h osp h in e Br id gin g Com p lexes
J uan Fornie´s,*,† Ana Garc´ıa,‡ J ulio Go´mez,‡ Elena Lalinde,*,‡ and
M. Teresa Moreno‡
Departamento de Quı´mica Inorga´nica, Instituto de Ciencia de Materiales de Arago´n,
Universidad de Zaragoza-Consejo Superior de Investigaciones Cientı´ficas,
50009 Zaragoza, Spain, and Departamento de Qu´ımica-Grupo de Sı´ntesis Quı´mica de
La Rioja, UA-CSIC, Universidad de La Rioja, 26006, Logron˜o, Spain
Received May 9, 2002
The monoalkynylphosphine complexes cis-[Pt(C6F5)2(PPh2CtCR)(tht)] (R ) Ph 1a , Tol 1b,
tBu 1c, tht ) tetrahydrothiophene) have been prepared by bridge splitting [{Pt(C6F5)2(µ-
tht)}2] or by displacement of only one tht ligand from cis-[Pt(C6F5)2(tht)2] with PPh2CtCR.
Complexes 1 react with cis-[Pt(C6F5)2(thf)2] to give binuclear derivatives [(C6F5)2Pt(µ-tht)-
(µ-1κP:2η2-PPh2CtCR)Pt(C6F5)2] (R ) Ph 2a , Tol 2b, tBu 2c), containing a mixed tht/PPh2Ct
CR bridging system. In contrast, treatment of 1 with [Pt(η2-C2H4)(PPh3)2] affords mixed-
valence Pt(II)-Pt(0) complexes [{(C6F5)2(tht)Pt(µ-1κP:2η2-PPh2CtCR)}Pt(PPh3)2] (R ) Ph
3a , Tol 3b) stabilized by only one κP:η2 bridging alkynyl phosphine. The molecular structures
of 2a and 3a have been confirmed by single-crystal X-ray diffraction. Similarly, reactions of
cis-bis(diphenylphosphino)alkyne complexes cis-[M(C6F5)2(PPh2CtCR)2] and cis-[Pt(CtCR′)2-
(PPh2CtCR)2] (M ) Pt, Pd; R ) Ph, Tol; R′) Ph, tBu) with 1 or 2 equiv of [Pt(η2-C2H4)-
(PPh3)2] yield the corresponding mixed-valence binuclear complexes cis-[{(C6F5)2M(PPh2Ct
CR)(µ-1κP:2η2-PPh2CtCR)}Pt(PPh3)2] (M ) Pt, R ) Ph 4a , Tol 4b; M ) Pd, R ) Ph 5a , Tol
5b) and cis-[{(CtCR′)2Pt(PPh2CtCR)(µ-1κP:2η2-PPh2CtCR)}Pt(PPh3)2] (R′ ) Ph, R ) Ph
6a , Tol 6b; R′ ) tBu, R ) Ph 7a , Tol 7b), bearing only one PPh2CtCR η2-coordinated to a
Pt(0)(PPh3)2 fragment.
In tr od u ction
phido (PPh2) and alkynide (CtCR) fragments,4 alkyne
coupling processes, and M-H or M-C insertion reac-
tions.1f,2c,5 Although all these coordination possibilities
have been described, it seems clear that P-coordination
is favored, especially with metal fragments in their
usual oxidation states. Alkyne coordination usually
requires a low-valent metal site, and this type of
coordination is favored only in a few cases.2 It should
be noted that even with low-valent metal fragments
the P-coordination competes effectively. Thus, previous
attempts to generate η2-alkyne complexes of zerovalent
Alkynyldiphenylphosphines PPh2CtCR have been
extensively used in transition metal chemistry, as they
are able to act as simple P-donor phosphines,1 as
disubstituted acetylenes,2 or to utilize the phosphorus
pair and the alkyne function simultaneously.3 Further-
more, in some cases, these ligands undergo cleavage
of the P-C(alkyne) bond to generate separate phos-
* Corresponding authors. E-mail: elena.lalinde@dq.unirioja.es;
forniesj@posta.unizar.es.
† Universidad de Zaragoza-CSIC.
‡ Universidad de La Rioja, UA-CSIC.
(3) (a) Carty, A. J .; Dimock, K.; Paik, H. N.; Palenik, G. J . J .
Organomet. Chem. 1974, 70, C17. (b) Carty, A. J .; Smith, W. F.; Taylor,
N. J . J . Organomet. Chem. 1978, 146, C1. (c) J acobson, S.; Carty, A.
J .; Mathew, M.; Palenik, G. J . J . Am. Chem. Soc. 1974, 96, 4330. (d)
Carty, A. J .; Paik, H. N.; Palenik, J . G. Inorg. Chem. 1977, 16, 300. (e)
Sappa, E.; Predieri, G.; Tiripicchio, A.; Tiripicchio-Camellini, M. J .
Organomet. Chem. 1985, 297, 103. (f) Lang, H.; Leise, M.; Zsolnai, L.
J . Organomet. Chem. 1991, 410, 379. (g) Louattani, E.; Suades, J .;
Alvarez-Larena, A.; Piniella J . F.; Germain, G. J . Organomet. Chem.
1996, 506, 121.
(4) (a) Carty, A. J . Pure Appl. Chem. 1982, 54, 113, and references
therein. (b) Blenkiron, P.; Enright, G. D.; Low, P. J .; Corrigan, J . F.;
Taylor, N. J .; Chi, Y.; Saillard, J .-Y.; Carty, A. J . Organometallics 1998,
17, 2447. (c) Carty, A. J .; Taylor, N. J .; Smith, W. F. J . Chem. Soc.,
Chem. Commun. 1979, 750. (d) Nuccianore, D.; MacLaughlin, S. A.;
Taylor, N. J .; Carty, A. J . Organometallics 1988, 7, 106. (e) Cherkas,
A. A.; Randall, L. H.; MacLauglin, S. A.; Mott, G. N.; Taylor, N. J .;
Carty, A. J . Organometallics 1988, 7, 969. (f) Bruce, M. I.; Willians,
M. L.; Patrick, J . M.; White, A. H. J . Chem. Soc., Dalton Trans. 1985,
1229. (g) Hogarth, G.; Rechmond, S. P. J . Organomet. Chem. 1997,
534, 221. (h) Patel, N. A.; Fisher, R. G.; Carty, A. J .; Naik, D. V.;
Palenik, G. J . J . Organomet. Chem. 1973, 60, C49. (i) Smith, W. F.;
Yule, J .; Taylor, N. J .; Paik, H. N.; Carty, A. J . Inorg. Chem. 1977, 16,
1593. (j) Carty, A. J .; MacLaughlin, S. A.; Van Wagner, J .; Taylor, N.
J . Organometallics 1982, 1, 1013.
(1) (a) Sappa, E.; Valle, M.; Predieri, G.; Tiripicchio, A. Inorg. Chim.
Acta 1984, 88, L23. (b) Wong, Y. S.; J acobson, S. E.; Chieh, P. C.; Carty,
A. J . Inorg. Chem. 1974, 13, 284. (c) Berau, G.; Carty, A. J .; Chieh, P.
C.; Patel, H. A. J . Chem. Soc., Dalton Trans. 1973, 488. (d) Louattani,
E.; Lledo´s, A.; Suades, J .; Alvarez-Larena, A.; Piniella, J . F. Organo-
metallics 1995, 14, 1053. (e) Louattani E.; Suades, J . J . Organomet.
Chem. 2000, 604, 234. (f) J ohnson, D. K.; Rukachaisirikul, T.; Sun,
Y.; Taylor, N. J .; Canty, A. J .; Carty, A. J . Inorg. Chem. 1993, 32, 5544.
(g) King, R. B.; Efraty, A. Inorg. Chim. Acta 1970, 4, 319. (h) Wheelock,
K. S.; Nelson, J . H.; J onassen, M. B. Inorg. Chim. Acta 1970, 4, 399.
(i) Simpson, R. T.; Carty, A. J . J . Coord. Chem. 1973, 2, 207. (j)
Louattani, E.; Suades, J . Inorg. Chim. Acta 1999, 291, 207. (k)
Louattani, E.; Suades, J .; Mathieu, R. J . Organomet. Chem. 1991, 421,
335. (l) Hengefeld, A.; Nast, R. J . Organomet. Chem. 1983, 252, 375.
(m) Hempsall, H. D.; Hyde, E. M.; Mentzer, E.; Saw, B. L. J . Chem.
Soc., Dalton Trans. 1997, 2285. (n) Lucas, N. T.; Cifuentes, M. P.;
Nguyen, L. T.; Humphrey, M. G. J . Cluster Sci. 2001, 12, 201. (o)
Bardaj´ı, M.; Laguna, A.; J ones, P. G. Organometallics 2001, 20, 3906.
(2) (a) Patel, H. A.; Carty, A. J .; Hota, N. K. J . Organomet. Chem.
1973, 50, 247. (b) Carty, A. J .; Paik, H. N.; Ng, T. W. J . Organomet.
Chem. 1974, 74, 279. (c) Bennett, M. A.; Castro, J .; Edwards, A. J .;
Kopp, M. R.; Wenger, E.; Willis, A. C. Organometallics 2001, 20, 980.
(d) Bennett, M. A.; Kwan, L.; Rae, A. D.; Wenger, E.; Willis, A. C. J .
Chem. Soc., Dalton Trans. 2002, 226.
10.1021/om020374w CCC: $22.00 © 2002 American Chemical Society
Publication on Web 07/30/2002

3734 Organometallics, Vol. 21, No. 18, 2002
Fornie´s et al.
Sch em e 1
palladium or platinum produced only P-coordinated
species M(PPh2CtCMe)4 (M ) Pt, Pd),1h although Carty
and co-workers have reported the synthesis of binuclear
derivatives [{M(µ-κP:η2-PPh2CtCF3)L}2] (M ) Pt, Pd;
L ) PPh2CtCF3, PPh3)3c containing two alkynylphos-
phine bridging ligands. Recently Bennett et al. have
shown that the reactions between the Ni(0) or Pt(0)
complexes [M(η2-C2H4)(dcpe)] (dcpe: 1,2-bis(dicyclo-
hexylphosphino)ethane) and PPh2CtCMe2c,d results in
the formation of the monomeric η2-alkynylphosphine
[M(η2-PPh2CtCMe)(dcpe)] complexes, although they are
formed through initial P-coordinated species, detected
at low temperature. Recently we have prepared com-
plexes containing κP:η2 bridging ligands starting from
Pt(II) precursors of the type cis-[MX2(PPh2CtCR)2]
(M ) Pt, Pd; X ) Cl, CtCR′) and examining their
reactivity toward the solvento species cis-[M(C6F5)2-
(thf)2] (M ) Pt, Pd; thf ) tetrahydrofuran) in 1:1 molar
ratio. This reactivity is versatile and dependent on the
X and the R groups. Thus, while the reactions with cis-
[MCl2(PPh2CtCR)2] led to (µ-Cl)2 (when R ) tBu) or
mixed µ-Cl/µ-PPh2CtCR (when R ) Ph) binuclear
complexes,6 only homo- and heterobimetallic double
alkynyl bridged (µ-CtCR)2 complexes were formed
by using cis-[Pt(CtCR′)2(PPh2CtCR)2] as precursors.7
Several unusual symmetrical [{(PPh2CtCtBu)2Pt(µ3-η2-
CtCPh)2}{M(C6F5)2}2] and [{Pt(µ-κP:η2-PPh2CtCPh)2-
(µ-η2-CtCtBu)2}{Pt(C6F5)2}2] trimetallic species were
also prepared when these cis-bis(alkynyl)bis(alkynyldi-
phenylphosphine) precursors react with cis-[M(C6F5)2-
(thf)2] in 1:2 molar ratio, confirming again the low η2-
bonding capability of the PPh2CtCtBu groups.7 More
recently we have observed that by forcing the η2-
complexation of both P-coordinated PPh2CtCR (R ) Ph,
Tol) molecules on cis-[M(C6F5)2(PPh2CtCR)2], the initial
bis(η2-alkyne) adducts [(C6F5)2M{µ-κPP:η2-(PPh2CtCR)2}-
Pt(C6F5)2] formed at low temperature evolve, through
an unexpectedly easy sequential insertion of both
PPh2CtCR molecules into a Pt-C6F5 bond, yielding
unusual µ-2,3-bis(diphenylphosphino)-1,3-butadien-1-yl
binuclear complexes.8
and characterization of novel P-coordinated monoalkyn-
ylphosphine complexes cis-[Pt(C6F5)2(PPh2CtCR)(tht)]
(R ) Ph, Tol, tBu) and examine their reactivity toward
cis-[Pt(C6F5)2(thf)2] and [Pt(η2-C2H4)(PPh3)2]. The prepa-
ration of unprecedented double hetero µ-tht/µ-PPh2Ct
CR and mono µ-κP:η2-PPh2CtCR bridged Pt(II)-Pt(II/0)
binuclear complexes is reported. Similar mixed-valence
M(II)-Pt(0) complexes bearing only a PPh2CtCR η2-
coordinated to the Pt(0)(PPh3)2 fragment are also gener-
ated by the reaction of cis-bis(alkynylphosphine) de-
rivatives cis-[MX2(PPh2CtCR)2] [M ) Pt, Pd; X ) C6F5,
CtCR′ (R′ ) Ph, tBu; R ) Ph, Tol)] with [Pt(η2-C2H4)-
(PPh3)2].
Resu lts a n d Discu ssion
To discover the behavior of complexes with only one
P-coordinated alkynylphosphine on a platinum frag-
ment, we have prepared the mononuclear complexes cis-
[Pt(C6F5)2(PPh2CtCR)(tht)] 1 [R ) Ph (a ), Tol (b), tBu8b
(c)]. These complexes are isolated as white, air-stable
solids by bridge splitting the tetrahydrothiophene-
bridged binuclear complex [{Pt(C6F5)2(µ-tht)}2] with the
appropriate alkynylphosphine (Scheme 1, i). Treatment
of the mononuclear cis-[Pt(C6F5)2(tht)2] with a molar
equiv of PPh2CtCR also results in the displacement of
only one tht ligand, providing an alternative method for
the synthesis of complexes 1 (Scheme 1, ii).
Analytical and spectroscopic data for these mixed-
ligand complexes 1 are given in the Experimental
Section. In the IR spectra the most remarkable absorp-
tions are (a) the ν(CtC) band (2163-2179 cm-1) due to
P-coordinated PPh2CtCR ligands and (b) a double
absorption corresponding to the X-sensitive modes of the
C6F5 groups (786-812 cm-1), which indicate a cis-
structure,9 which is unequivocally confirmed by 19F
NMR spectroscopy. The presence of tht and PPh2Ct
Continuing with our interest in η2-coordinated alkyn-
ylphosphines, in this work, we describe the synthesis
CR ligands is, as expected, established by 13C{1H}, H
1
(5) (a) Carty, A. J .; Taylor, N. J .; J ohnson, D. K. J . Am. Chem. Soc.
1979, 101, 5422. (b) Bennett, M. A.; Cobley, Ch. J .; Rae, A. D.; Wenger,
E.; Willis, A. C. Organometallics 2000, 19, 1522. (c) Liu, X.; Mok, K.
F.; Leung, P.-H. Organometallics 2001, 20, 3918. (d) Edwards, A. J .;
Macgregor, S. A.; Rae, A. D.; Wenger, E.; Willis, A. C. Organometallics
2001, 20, 2864. (e) Davies, J . E.; Mays, M. J .; Raitbhy, P. R.;
Sarveswaran, K.; Solan, G. A. J . Chem. Soc., Dalton Trans. 2001, 1269.
(f) Miquel, Y.; Cadierno, V.; Donnadieu, B.; Igau, A.; Mayoral, J .-P.
Organometallics 2000, 19, 54. (g) Miquel, Y.; Igau, A.; Donnadieu, B.;
Mayoral, J .-P.; Pirio, N.; Meunier, P. J . Am. Chem. Soc. 1998, 120,
3504. (h) Miquel, Y.; Igau, A.; Donnadieu, B.; Mayoral, J . P.; Dupuis,
L.; Pirio, N.; Meunier, P. Chem. Commun. 1997, 279. (i) Dupuis, L.;
Pirio, N.; Meunier, P.; Igau, A.; Donnadieu, D.; Mayoral, J .-P. Angew.
Chem., Int. Ed. Engl. 1997, 36, 987. (j) Bennett, M. A.; Cobley, Ch. J .;
Wenger, E.; Willis, A. C. Chem. Commun. 1998, 1307. (k) Dickson, R.
S.; De Simone, T.; Parker, R. J .; Fallon, G. D. Organometallics 1997,
16, 1531. (l) Rosa, P.; Le Floch, P.; Ricard, L.; Mathey, F. J . Am. Chem.
Soc. 1997, 119, 9417. (m) Montlo, D.; Suades, J .; Dahan, F.; Mathieu,
R. Organometallics 1990, 9, 2933, and references therein. (n) Liu, X.;
Ong, T. K. W.; Selvaratnam, S.; Vittal, J . J .; White, A. J . P.; Williams,
D. J .; Leung, P.-H. J . Organomet. Chem. 2002, 643, 4.
(tht, S-R-CH2 36.8-36.9/2.83-2.89; â-CH2 29.4-29.6/
1.69-1.71), and 31P{1H} (δP -5.71 to -7.22; J Pt-P
1
2470-2482 Hz) NMR spectroscopy. The uncoordinated
alkyne carbons are found as doublets in the expected
chemical shift ranges with the CR carbon resonances
clearly upfield shifted with regard to those of free
PPh2CtCR ligands (∆ -7.9 1a , -6.82 1b, -6.9 1c). In
accordance with previous observations, the Câ signals
are less affected (∆ -1.3 1a , +0.74 1b, 0 1c) by simple
P-coordination of the ligands, and consequently the
chemical shift differences δCâ-δCR, which have been
previously related to the triple-bond polarization,1d,4a,10,11
increase with respect to those of free alkynyl phos-
phines.
(6) Fornie´s, J .; Lalinde, E.; Mart´ın, A.; Moreno, M. T.; Welch, A. J .
J . Chem. Soc., Dalton Trans. 1995, 1333.
(7) Ara, I.; Falvello, L. R.; Ferna´ndez, S.; Fornie´s, J .; Lalinde, E.;
Mart´ın, A.; Moreno, M. T. Organometallics 1997, 16, 5923.
(8) (a) Chartmant, J . P. H.; Fornie´s; J .; Go´mez, J .; Lalinde, E.;
Moreno, M. T.; Orpen, A. G.; Solano, S. Angew. Chem., Int. Ed. 1999,
38, 3058. (b) Ara, I.; Fornie´s, J .; Garc´ıa, A.; Go´mez, J .; Lalinde, E.;
Moreno, M. T. Chem. Eur. J . (in press).
(9) Maslowsky, E., J r. Vibrational Spectra of Organometallic
Compounds; Wiley: New York, 1977; p 437.
(10) (a) Rossenberg, D.; Drenth, W. Tetrahedron 1971, 27, 3893. (b)
Albright, T. A.; Freeman, W. J .; Schweizer, E. E. J . Am. Chem. Soc.
1975, 97, 2946.
(11) Berenguer, J . R.; Bernechea, M.; Fornie´s, J .; Lalinde, E.; Go´mez,
J . Organometallics 2002, 21, 2314.

Pt(II)-Pt(II) and Pt/ Pd(II)-Pt(0) Bridging Complexes
Organometallics, Vol. 21, No. 18, 2002 3735
Sch em e 2
F igu r e 1. Molecular structure of [(C6F5)2Pt(µ-tht)(µ-1κP:
2η2-PPh2CtCPh)Pt(C6F5)2], 2a . Ellipsoids are drawn at the
50% probability level. Hydrogen atoms have been omitted
for clarity.
Ta ble 1. Selected Bon d Len gth s (Å) a n d
An gles (d eg)
[(C6F 5)2P t(µ-th t)(µ-1KP :2η2-P P h 2CtCP h )P t(C6F 5)2]
The reactivity of complexes 1 toward the Pt(II) and
Pt(0) substrates,, cis-[Pt(C6F5)2(thf)2] and [Pt(η2-C2H4)-
(PPh3)2], respectively, has been examined and the
results of these reactions are summarized in Scheme 2.
Treatment of cis-[Pt(C6F5)2(PPh2CtCR)(tht)] (R ) Ph
1a , Tol 1b, tBu 1c) with 1 equiv of cis-[Pt(C6F5)2(thf)2]
at room temperature in CH2Cl2 immediately gives the
binuclear heterobridged [(C6F5)2Pt(µ-tht)(µ-1κP:2η2-
PPh2CtCR)Pt(C6F5)2] (R ) Ph 2a , Tol 2b, tBu 2c)
complexes in good (2a , 2b) or moderate (2c) yields
(Scheme 2, i). Complexes 2, which are isolated as white
solids, are stable in the solid state but not in solution.
The dimetallic formulation with the mixed hetero-
bridged (µ-tht)(µ-PPh2CtCR) system is consistent with
their analytical and spectroscopic data and has been
confirmed by an X-ray diffraction study on complex 2a .
Evidence for the coordination of the CtC bond comes
from the infrared spectra, which show two absorptions
(1982-2059 cm-1) [one of them weak (2a , 2b)] or one
broad band (2c) due to ν(CtC) and in the range of
Pt(II)-coordinated carbon-carbon triple bonds.6,7,11 The
bridging nature of the tht ligand as well as the asym-
metric formulation of the dimers can be inferred from
the 1H NMR spectra, which show, at room temperature,
two different signals for both the R-CH2 (δ 3.82-3.18)
and â-CH2 [δ 2.17-1.55, only one broad (4H) signal
for 2c] proton resonances. It is remarkable that the
R-proton resonances, in particular, are deshielded by
about 1 ppm compared with those observed in the
corresponding starting materials 1. The 19F NMR
spectra at room temperature confirm the presence of
four rigid nonequivalent C6F5 groups (four para-fluorine
triplets and AA′MXX′ spin systems), and the 31P{1H}
NMR spectra show a singlet resonance (δ 24.25-22.09)
with platinum satellites (J Pt-P 2359-2332 Hz) which
is notably shifted to higher frequencies (∆ 29.95 2a ,
30.12 2b, 29.31 2c) with respect to those of 1. This
downfield shift has been previously observed in other
complexes containing µ-µ:η2-PPh2CtCR ligands, it being
attributed to the loss of the electron ring current
associated with the π-CtC bonds upon complex-
ation.3,6,7,10,11
(2a ‚0.5C6H14
)
Pt(1)-C(1)
Pt(1)-C(7)
Pt(1)-P(1)
Pt(1)-S(1)
Pt(2)-C(19)
Pt(2)-C(13)
Pt(2)-C(29)
2.041(5)
2.078(4)
2.2706(11)
2.3447(11)
2.027(5)
2.046(4)
2.205(4)
Pt(2)-C(30)
Pt(2)-S(1)
P(1)-C(29)
S(1)-C(28)
S(1)-C(25)
C(29)-C(30)
2.342(5)
2.3813(11)
1.784(5)
1.842(5)
1.848(5)
1.203(7)
C(1)-Pt(1)-C(7)
C(1)-Pt(1)-P(1)
C(7)-Pt(1)-S(1)
P(1)-Pt(1)-S(1)
86.32(18) C(19)-Pt(2)-S(1)
90.34(13) C(29)-Pt(2)-S(1)
95.06(13) Pt(1)-S(1)-Pt(2)
88.38(4) C(30)-C(29)-P(1)
90.82(13)
84.37(12)
117.54(5)
156.2(4)
C(19)-Pt(2)-C(13) 86.64(18) C(29)-C(30)-C(31) 167.9(5)
C(13)-Pt(2)-C(29) 98.52(17) P(1)-C(29)-Pt(2)
C(13)-Pt(2)-C(30) 81.18(18)
117.7(2)
The single-crystal X-ray structure of 2a confirms that
a diphenyl(phenylethynyl)phosphine group and a tht
ligand bridge two identical “cis-Pt(C6F5)2” platinum
fragments. The molecular geometry is presented in
Figure 1, and selected bond distances and angles are
listed in Table 1. The alkynylphosphine ligand acts
as a four-electron donor with the phosphorus atom
bonded to Pt(1) and the alkyne function to Pt(2). It
should be noted that heterobridged systems of the type
(µ-κP:η2-PPh2CtCR)(µ-X) are very scarce. As far as we
know, the only examples characterized by X-ray diffrac-
tion are the recently described dinuclear derivatives
[(C6F5)2Pt(µ-Cl)(µ-1κP:2η2-PPh2CtCPh)PtCl(PPh2Ct
CPh)],6 obtained by the reaction of cis-[PtCl2(PPh2Ct
CPh)2] with cis-[Pt(C6F5)2(thf)2], the trinuclear complex
[{cis-Pt(µ-κP:η2-PPh2CtCPh)2(µ-η1:η2-PPh2CtCtBu)2}-
{Pt(C6F5)2}2],7 in which two terminal “cis-Pt(C6F5)2”
moieties are linked to a central platinum atom through
both alkynyl units (µ-η2) and both alkynylphosphine
ligands (µ-κP:η2), and the d6-d8 species [(PPh2CtCPh)-
Cp*Ru(µ-Cl)(µ-κP:η2-PPh2CtCPh)Pt(C6F5)2].11 In addi-
tion, several X-ray-characterized examples of platinum
complexes with tht bridging ligands are known, in
particular (NBu4)2[trans-PtCl2{(µ-tht)Pt(C6F5)3}2]12 (tht
monobridge), (NBu4)[Pt2Ag(µ-tht)2(C6F5)6]13 (tht mono-
(12) Uso´n, R.; Fornie´s, J .; Toma´s, M.; Ara, I. J . Chem. Soc., Dalton
Trans. 1989, 1011.

3736 Organometallics, Vol. 21, No. 18, 2002
Fornie´s et al.
bridge between a silver center and a platinum center),
[(C6F5)2Pt(µ-tht)(µ-dppm)Pt(C6F5)2]14 (mixed µ-tht/µ-
dppm bridge), and [trans-PtCl2{(µ-tht)(C6F5)3PtAg(η2-
C6H5Me}2].15
Both platinum centers are located in distorted square-
planar environments, with a cis arrangement of the
C6F5 groups, the Pt-C(C6F5) distances being perceptibly
different [range 2.027(5)-2.078(4) Å] (although within
the range found in other pentafluorophenyl derivatives),
reflecting the presence of different trans ligands.
The µ-tht ligand is located asymmetrically [Pt(1)-S
2.3447(11), Pt(2)-S 2.3813(11) Å] between the two
nonbonded platinum centers [Pt‚‚‚Pt 4.042 Å], the angle
at sulfur [117.54(5)°] being comparable to those found
in related complexes.12,14,15 The plane SC(25)C(28) is
almost orthogonal (95.68°) to the plane defined by two
platinum atoms and the sulfur. The C-C alkyne dis-
tance [1.203(7) Å] and the angles at the acetylenic
carbons of the PPh2CtCPh ligand [C(30)-C(29)-P(1)
156.2(4)° and C(29)-C(30)-C(31) 167.9(5)°] follow the
usual pattern observed for η2-coordinated phosphino-
alkynes, the Pt(2)-π(alkyne) bond distances [Pt(2)-
C(29) 2.205(4), Pt(2)-C(30) 2.342(5) Å] being compa-
rable to those found in related platinum(II) derivatives.6,7
As expected for a η2-interaction to a d8 metal center,
the C(29)-C(30) acetylenic fragment is oriented by 40.2°
to the local Pt(2) coordination plane. The resulting
central core is not planar, the dihedral angle formed by
the best square-planar metal coordination planes around
Pt(1) and Pt(2) being 34.6°.
As is shown in Scheme 2, the uncoordinated alkyne
function in 1 could also react with Pt(0) substrates to
produce mixed-valence Pt(II)-Pt(0) bridging alkynylphos-
phine complexes. Thus, complexes cis-[Pt(C6F5)2(PPh2Ct
CR)(tht)] 1a and 1b react in acetone with [Pt(η2-C2H4)-
(PPh3)2] to give, in moderate yields, the novel [{(C6F5)2-
(tht)Pt(µ-1κP:2η2-PPh2CtCR)}Pt(PPh3)2] (R ) Ph 3a ,
Tol 3b ) complexes (Scheme 2, ii), stabilized by only
one κP:η2-PPh2CtCR bridging ligand. Under similar
reaction conditions, the tert-butylalkynylphosphine com-
plex 1c does not react with the Pt(0) substrate, and
under more drastic conditions, decomposition takes
place and most of the Pt(II) starting material is recov-
ered. These results are in agreement with previous
observations5b,6,7 which indicate the very low η2-bonding
capability of the P-bonded PPh2CtCtBu ligands toward
unsaturated metal fragments. In this context, the
driving force for the formation of the binuclear deriva-
tive 2c could be attributed to the simultaneous presence
of the tetrahydrothiophene bridging ligand. It is worth
noting that binuclear Pt(I)-Pt(I) derivatives without
supporting bridging ligands have been previously ob-
tained by redox condensation reactions between cis-[Pt-
(C6X5)2L2] (X ) F, Cl; L ) CO, CNR) and [Pt(η2-
C2H4)(PPh3)2].16 In this context, although the formation
of the mixed Pt(II)-Pt(0) complexes 3 can be easily
envisioned due to the presence of an uncoordinated
alkyne fragment on the precursor derivatives 1, its
F igu r e 2. View of the molecular structure of [{(C6F5)2-
(tht)Pt(µ-1κP:2η2-PPh2CtCPh)}Pt(PPh3)2], 3a . Ellipsoids
are drawn at the 50% probability level. Hydrogen atoms
have been omitted for clarity, and the phenyl groups bound
to the phosphorus atoms are represented by their ipso-
carbons only.
formation is remarkable, as binuclear Pt(I)-Pt(I) de-
rivatives or more simple Pt(II)-Pt(II) phosphide/
alkynide species could have been also obtained by simple
P-C(alkyne) bond cleavage.4
Complexes 3a and 3b are moderately stable in the
solid state but decompose slowly in solution with the
loss of the Pt(0) fragment and regeneration of the
corresponding mononuclear derivatives 1. The presence
of η2-complexed fragments in these complexes is inferred
from their IR spectra. They display one ν(CtC) absorp-
tion (1715 cm-1 3a , 1714 cm-1 3b) in the typical region
of coordinated triple bonds. The remarkable shifts in
relation to the monomers 1 (∆CtC 464 3a ; 457 cm-1
3b) are consistent with a simple η2-coordination to the
Pt(0) center,2d,3c,17 the precursor platinum(II) center
retaining coordination through the phosphorus atom.
The proton resonances of the terminal tht ligand give
rise to two broad signals at very low frequency (δ 1.99,
1.14 3a ; 1.98, 1.16 3b) in relation to the starting
materials. This high-field shift could be tentatively
attributed to the shielding effect of the aromatic group
on the CtCR fragment. As is observed in Figure 2,
which shows the crystal structure of 3a , the η2-
coordination to Pt(0) causes a considerable distortion
on the acetylenic fragment, placing the aromatic ring
close to the tht protons [the closest protons: H(33a);
H(33b)‚‚‚ring-C(27)-C(32) 2.837; 2.968 Å]. The 31P
NMR spectra at room temperature (see Table 2) of
complexes 3a and 3b show poorly resolved ABM spin
systems with the corresponding platinum satellites. The
two most deshielded signals (at ca. δ 24) are attributed
to the inequivalent phosphorus atoms of PPh3 ligands
1
bonded to Pt(0), since they show the larger J Pt-P
couplings and in the typical range of Pt(0)-alkyne
complexes.2d,17 The low-frequency resonance (δ ≈ -16)
(13) Uso´n, R.; Fornie´s, J .; Falvello, L. R.; Toma´s, M.; Casas, J . M.;
Mart´ın, A. Inorg. Chem. 1993, 32, 5212.
(14) Casas, J . M.; Falvello, L. R.; Fornie´s, J .; Mart´ın, A. Inorg. Chem.
1996, 35, 7867.
(15) Uso´n, R.; Fornie´s, J .; Toma´s, M.; Ara, I. J . Chem. Soc., Dalton
Trans. 1990, 3151.
(16) Uso´n, R.; Fornie´s, J .; Espinet, P.; Fortun˜o, C.; Toma´s, M.; Welch,
A. J . J . Chem. Soc., Dalton Trans. 1989, 1583.
(17) (a) Ara, I.; Berenguer, J . R.; Eguiza´bal, E.; Fornie´s, J .; Go´mez
J .; Lalinde, E.; Sa´ez-Rocher J . Organometallics 2000, 19, 4385. (b)
Yamazaki, S.; Deeming, A. J .; Speel, D. M. Organometallics 1998, 17,
775. (c) Schager, F.; Bonrath, W.; Po¨rschke, K.-R.; Keesler, M.; Kru¨ger,
C.; Seevogel, K. Organometallics 1997, 16, 4276. (d) Boag, N. M.; Green,
M.; Grove, D. M.; Howard, J . A. K.; Spencer, J . L.; Stone, F. G. A. J .
Chem. Soc., Dalton Trans. 1980, 2170. (e) Heyns, J . B. B.; Stone, F.
G. A. J . Organomet. Chem. 1978, 160, 337.

Pt(II)-Pt(II) and Pt/ Pd(II)-Pt(0) Bridging Complexes
Organometallics, Vol. 21, No. 18, 2002 3737
1
Ta ble 2. 31P {1H} NMR Da ta a t 20 °C for Com p lexes 3-7 (δ in p p m , J in Hz, J P t-P in br a ck ets)
compound
δ PA
δ PB
δ PM
δ PQ
2J PA-PB
3J PA-PM
3J PB-PM
2J PM-PQ
3a a
24.84 (s, br)
[3493]
24.38 (s, br)
[3643]
-16.00 (s, br)
[2386]
3ba
4a a
4bb
5a b
5bb
6a b
6ba
7a a
7bb
24.85 (s, br)
-15.70 (s, br)
[3480]
25.64
[3492]
25.72
[3474]
25.79
[3488]
25.81
[3638]
24.26
[3674]
24.74
[3685]
24.09
[3685]
24.34
[2391]
-8.54
[2428]
-8.93
[2462]
-14.28
[2315]
-15.30
[2337]
-7.75
27.9
27.9
27.2
27.6
20.3
29.7
27.5
27.6
17.7
27.6
23.1
19.7
-3.94
-4.19
-7.97
[3470]
[3687]
24.90
1.94
[2381]
0.04
-10.3
c
c
c
c
c
c
c
[3535]
[3737]
25.00
[3645]
[2325]
-10.36
[2338]
-10.56
[2292]
-10.73
[2284]
18.8
18.6
c
c
24.33
[3770]
25.30
[3460]
5.11
[2418]
4.88
26.8
45.7
28.4
25.40
c
c
c
[≈3443]
[≈3648]
[2426]
In CDCl3. In CD3COCD3. c It cannot be calculated.
a
b
Ta ble 3. Selected Bon d Len gth s (Å) a n d
An gles (d eg) for
only 5.07°. The torsion angle P(1)-C(25)-C(26)-C(27)
is 0.7°. The Pt-C(sp) acetylenic distances [Pt(2)-
C(25) 2.083(3); Pt(2)-C(26) 2.049(3) Å] are shorter than
those observed in 2a . The C(25)-Pt(2)-P(3) angle
[118.42(10)°] is slightly larger than that of C(26)-Pt(2)-
P(2) [102.56(10)°], probably due to greater steric hin-
drance of the PPh2 end. As expected, the CtC bond
[1.302(5) Å] is perceptibly longer than that in the
Pt(II)-Pt(II) derivative 2a [1.203(7) Å], and the bend
back angles at CR and Câ are more acute [137.0(3)°/
144.6(3)° in 3a vs 156.2(4)°/167.9(5)° in 2a ]. Both facts
are consistent with back-bonding from Pt(2) into the π*
CtC orbital, affording some metallacyclopropene char-
acter to the bonding. However, the P(1)-C(acetylenic)
distances are almost identical in both complexes [P(1)-
C(25) 1.770(3) Å in 3a versus P(1)-C(29) 1.784(5) Å in
2a ]. The Pt(1) atom retains its square-planar geometry
and is bonded to the Cipso carbon atoms of the two
mutually cis C6F5 groups, to the phosphorus atom of the
bridging PPh2CtCPh ligand, and to the sulfur atom of
the terminal tht ligand. The Pt(1)-P(1) bridging bond
distance [2.3010(8) Å] is slightly longer than the corre-
sponding one in 2a [2.2706(11) Å]. However, the termi-
nal Pt(1)-S(1) distance [2.3461(9) Å] is similar within
experimental error to the Pt-S bridging distance in 2a
[2.3447(11) Å].
[{(C6F 5)2(th t)P t(µ-1KP :2η2-P P h 2CtCP h )}P t(P P h 3)2]
(3a ‚CH2Cl2)
Pt(1)-C(1)
Pt(1)-C(7)
Pt(1)-P(1)
Pt(1)-S(1)
S(1)-C(33)
S(1)-C(36)
2.076(3)
2.032(3)
2.3010(8)
2.3461(9)
1.829(4)
1.835(4)
Pt(2)-C(26)
Pt(2)-C(25)
Pt(2)-P(2)
Pt(2)-P(3)
C(25)-C(26)
P(1)-C(25)
2.049(3)
2.083(3)
2.2889(9)
2.3048(9)
1.302(5)
1.770(3)
C(7)-Pt(1)-C(1)
C(7)-Pt(1)-P(1)
C(1)-Pt(1)-S(1)
P(1)-Pt(1)-S(1)
85.47(13) C(25)-P(1)-Pt(1) 116.26(12)
91.02(9) C(26)-Pt(2)-P(2) 102.56(10)
95.47(10) P(2)-Pt(2)-P(3)
88.15(3) C(26)-C(25)-P(1) 137.0(3)
C(25)-Pt(2)-P(3) 118.42(10)
102.37(3)
C(25)-C(26)-C(27) 144.6(3)
is assigned to the alkynylphosphine bridging ligand
(PM). It is noteworthy that, in contrast to that observed
for the alkynylphosphine-bridged Pt(II)-Pt(II) com-
plexes 2, the phosphorus resonance of the PPh2 group
in these mixed-valence Pt(II)-Pt(0) derivatives 3 is
significantly more shielded than in the mononuclear
precursors 1a and 1b, but as expected, these phosphorus
atoms are still deshielded in relation to the free ligands
(PPh2CtCPh δ -33.53; PPh2CtCTol -32.42).
Crystals of the derivative 3a suitable for single-
crystal X-ray diffraction were obtained by slow diffusion
(-30 °C) of n-hexane into a CH2Cl2 solution of the
complex. The molecular structure is depicted in Figure
2, and selected bond lengths and angles are indicated
in Table 3. The structure confirms the η2-alkyne coor-
dination of the P-coordinated PPh2CtCPh ligand to the
Pt(PPh3)2 fragment. The Pt(2) center displays a close
to planar trigonal coordination, typical of metal (d10)-
alkyne complexes,2d,17a,18 the dihedral angle between
planes P(2)-Pt(2)-P(3) and C(25)-Pt(2)-C(26) being
As we commented in the Introduction, we have
recently reported the reactivity of cis-[MX2(PPh2Ct
CR)2] (X ) C6F5, M ) Pt, Pd; X ) CtCR′, M ) Pt)
toward the solvento tetrahydrothiophene Pt(II) complex
(18) (a) Hartley, F. R. In Comprehensive Organometallic Chemistry;
Wilkinson, G., Stone, F. G. A., Abel, E. W., Eds.; Pergamon Press:
Oxford, U.K., 1982; Vol. 6. (b) Comprehensive Organometallic Chem-
istry II; Wilkinson, G., Stone, F. G. A., Abel, E. W., Eds.; Puddephatt,
R. J ., Vol. Ed.; Pergamon Press: Oxford, U.K., 1995; Vol. 9, Chapter
9. (c) Ittel, S. D.; Ibers, J . A. Adv. Organomet. Chem. 1976, 14, 33.

3738 Organometallics, Vol. 21, No. 18, 2002
Fornie´s et al.
Sch em e 3
F igu r e 3. Schematic view of the preliminary X-ray dif-
fraction study of 5a showing the connectivity of the atoms.
For the sake of clarity, the phenyl groups bound to the
phosphorus atoms are represented by their ipso-carbons
only.
which is related to the higher ν(CtC) frequencies
observed in P-bonded alkynylphosphines with respect
to free ligands, could probably increase the π-acceptor
nature of the acetylenic entity. In addition, the decrease
of electron density at the phosphorus atom caused by
complexation and reflected in part by low-field shifts
(∆δ for [Pt(CtCR′)2(PPh2CtCR)2] 26.03-27.4) will also
increase the electronegativity of P and raise the prefer-
ence of the acetylenic M-PCtCR entity toward rela-
tively low valent metal fragments.
cis-[Pt(C6F5)2(thf)2]. The reactions of cis-[M(CtCR′)2-
(PPh2CtCR)2] with 1 equiv of the solvento complex lead
to binuclear derivatives stabilized by alkynyl bridging
ligands [{(PPh2CtCR)2Pt(µ-CtCR′)2}Pt(C6F5)2],7 indi-
cating that alkynyl groups possess a higher η2-bonding
capability to Pt(II) than alkynylphosphine ligands. In
addition, we have shown that unusual µ-2,3-bis(diphen-
ylphosphino)-1,3-butadien-1-yl binuclear compounds,
which are the first examples of insertion of an acetylenic
fragment into the robust Pt-C6F5 bond, are the only
final species when the solvento complex cis-[Pt(C6F5)2-
(thf)2] reacts with cis-[Pt(C6F5)2(PPh2CtCR)2] (R ) Ph,
Tol).8 In this context and for comparative purposes, we
decided to examine the reactivity of these cis-bis-
(diphenylphosphino)alkyne mononuclear derivatives,
cis-[M(C6F5)2(PPh2CtCR)2] (M ) Pt, Pd; R ) Ph, Tol)
and cis-[Pt(CtCR′)2(PPh2CtCR)2] (R ) Ph, Tol; R′) Ph,
tBu), toward [Pt(η2-C2H4)(PPh3)2]. Following a procedure
similar to that used for complexes 3, the reactions of
the ethylene Pt(0) derivative [Pt(η2-C2H4)(PPh3)2] with
the mononuclear Pt(II) or Pd(II) starting materials
(Scheme 3) in acetone also resulted in the formation of
white solids, which were identified as the mixed-valence
complexes cis-[{(C6F5)2M(PPh2CtCR)(µ-1κP:2η2-PPh2Ct
CR)}Pt(PPh3)2] (M ) Pt, R ) Ph 4a , Tol 4b; M ) Pd,
R ) Ph 5a , Tol 5b) and cis-[{(CtCR′)2Pt(PPh2CtCR)-
(µ-1κP:2η2-PPh2CtCR)}Pt(PPh3)2] (R′ ) Ph, R ) Ph 6a ,
Tol 6b; R′ ) tBu, R ) Ph 7a , Tol 7b), respectively, with
a Pt(PPh3)2 fragment attached to the acetylenic bond
of one alkynylphosphine group. The formation of bi-
nuclear derivatives 6 and 7 clearly indicates that Pt(0)
has a much stronger preference for the π-donor acetyl-
enic density of P-bonded alkynylphosphines than for
that of the alkynyl ligands. This is in contrast to the
behavior of Pt(II) or Pd(II) complexes since unsaturated
metal fragments such as cis-[M(C6F5)2(thf)2] form ex-
clusively double alkynide bridged systems. This differ-
ence can be explained in terms of a stronger π-acceptor
ability of the -PCtCR unit, which favors coordination
to the relatively electron rich Pt(0). Recent theoretical
calculations have shown that P-complexation of these
ligands reduces the π*CtC occupancy.1d This fact,
It should be noted that complexes 4-7 are moderately
stable in the solid state, but on standing in solution,
decompose with the loss of the Pt(PPh3)2 fragment,
regenerating the corresponding mononuclear complexes.
Compounds 4 and 5 are in fact always accompanied by
trace amounts of starting Pt(II) materials, and these
impurities could not be eliminated since attempts to
recrystallize the solids caused the breakdown of the η2-
alkyne interaction. Similar reactions were attempted
between cis-[Pt(C6F5)2(PPh2CtCtBu)2] or cis-[Pt(Ct
CR′)2(PPh2CtCtBu)2] (R′ ) Ph, Tol) and [Pt(η2-C2H4)-
(PPh3)2], but in all cases, the Pt(II) precursors remained
unreacted in solution, even after longer reaction times,
confirming again the lower η2-bonding capability of
PPh2CtCtBu ligands. We also noted that attempts to
involve both PPh2CtCR groups in η2-coordination failed.
Thus, treatment of cis-[Pt(C6F5)2(PPh2CtCTol)2] or cis-
[Pt(CtCR′)2(PPh2CtCPh)2] with 2 molar equiv of [Pt-
(η2-C2H4)(PPh3)2] yielded only the corresponding binu-
clear complexes 4b, 6a , and 7a , indicating that the
second alkynylphosphine ligand is not a good potential
site for further coordination.
Compounds 4-7 have been characterized by usual
1
analytical and spectroscopic [IR and H, 19F, 31P{1H},
and 13C{1H} NMR (4b, 7a )] means (see Experimental
Section and Table 2 for details). In addition, the
formulations proposed were backed by an X-ray diffrac-
tion study of complex 5a (Figure 3). Although the poor
quality of all crystals obtained prevented their satisfac-
tory refinement, the connectivity, shown in Scheme 3,
was unequivocally established, confirming the presence
of a palladium(II) organometallic fragment “cis-Pd-
(C6F5)2(PPh2CtCPh)2”, which acts as a monoacetylenic

Pt(II)-Pt(II) and Pt/ Pd(II)-Pt(0) Bridging Complexes
Organometallics, Vol. 21, No. 18, 2002 3739
ligand toward the low-valent metal in the Pt(PPh3)2
unit.
The IR spectra of 4-7 confirm the presence of
bridging and terminal alkynylphosphine ligands. Thus,
they exhibit two (4, 5, 7) or three (6) ν(CtC) absorptions;
the low-frequency band (1691-1756 cm-1), which ap-
pears with a shoulder (except in 4) at a position similar
to those observed in 3, is assigned to the alkynylphos-
phine bridging group and the remaining high-frequency
absorptions to the terminal P-coordinated PPh2CtCR
(2173-2177 cm-1) or alkynide (2121 6a , 2123 cm-1 6b)
ligands. The most relevant feature of the room-temper-
1
ature H NMR spectra is the presence of two different
methyl signals in the tolyl derivatives (4b, 5b, 6b, 7b)
as well as two singlets attributed to the tBu groups in
the tert-butylalkynyde complexes 7. Complexes 4 and
5, containing C6F5 groups, display at -50 °C a 19F NMR
pattern characteristic of a rigid molecule (two different
sets of resonances due to rigid C6F5 rings with non-
equivalent halves). On raising the temperature, the two
o-fluorine (and meta) resonances broaden and collapse
near room temperature, to only one due to a fast
rotation of C6F5 groups around their Pt-C bonds. The
31P{1H} NMR data (20 °C) for these complexes (4-7)
are shown in Table 2. All complexes display an ABMQ
splitting pattern with the corresponding 195Pt satellites,
and from the analysis of the ABM part of the spectrum,
δPA, δPB, δPM, 2J PA-PB, 3J PA-PM, and 3J PB-PM are directly
obtained. The analyses of the spectra obtained are
consistent with the simulations carried out for all
complexes using the g-NMR program (v3.6 for Macin-
tosh). As an illustration both the real and simulated
spectra of complex 7a are presented in Figure 4. The
two low-field resonances (δP 25.81-24.09, AB part) are
due to the inequivalent phosphorus atoms bonded to
Pt(0), and as noted in Table 2, the more deshielded
resonance is, in each case (except in 7a ), attributed to
PA trans to the PPh2 end on the basis of the larger
3J PM-P coupling. The next higher-field signal (δ 5.11 to
-8.93) appears as a complex multiplet due to extra
coupling to PQ and is attributed to the phosphorus atom
(PM) of the alkynylphosphine bridging ligand. Finally,
the strongly shielded signal (δ -7.75 to -15.30), which
occurs as a doublet (2J PM-PQ 18.8, 18.6 Hz, in complexes
6b and 7a ) is clearly assigned to the phosphorus of
terminal P-coordinated alkynylphosphine (PQ). In com-
plexes 4 and 5, the presence of C6F5 trans to PM and PQ
gives rise to somewhat broad signals due to further
unresolved coupling to o-fluorine nuclei. In keeping with
what is observed in complexes 3, the one-bond Pt(0)-
PA,B coupling constants (3443-3770 Hz) are again
notably larger than the corresponding Pt(II)-PM,Q
(2284-2462 Hz). Due to solubility and/or stability
problems, only the 13C NMR spectra of 4b and 7b at
low temperature could be recorded. For complex 4b, the
acetylenic carbon signals corresponding to the terminal
P-coordinated PPh2CtCTol ligands resonate close to
F igu r e 4. Real (a) and simulated (b) 31P{1H} NMR spectra
of 7a .
to those observed in the starting material (see Experi-
mental Section for details), but the alkynyl carbons of
the alkynyl bridging κP:η2-coordinated phosphine are
not seen. The assignments of CR and Câ are based on
the observation of the phosphorus-carbon coupling.
Con clu sion s
In summary we report the preparation of some
potentially useful platinum(II) complexes bearing a
diphenylalkynylphosphine molecule and a tht ligand in
mutually cis position, cis-[Pt(C6F5)2(PPh2CtCR)(tht)] 1,
and investigate their reactivity toward cis-[Pt(C6F5)2-
(thf)2] and [Pt(η2-C2H4)(PPh3)2]. We have shown that
while complexes 1 react with the solvento derivatives
cis-[Pt(C6F5)2(thf)2] to give the first reported examples
of hetero (µ-tht)/(µ-κP:η2-PPh2CtCR) bridged diplati-
num(II) complexes, the reaction with the ethylene
platinum(0) complex results in the formation of the
single µ-κP:η2-PPh2CtCR bridged mixed-valence Pt(II)-
Pt(0) complexes accessible through η2-alkyne complex-
ation of the Pt(PPh3)2 unit. By comparison, the reactivity
of [Pt(η2-C2H4)(PPh3)2] toward several cis-bis(alkynyl-
phosphine) cis-[MX2(PPh2CtCR)2] (X ) C6F5, M ) Pt,
Pd; X ) CtCR′, M ) Pt) has also been examined,
showing that the behavior of these substrates bearing
two alkynylphosphine ligands resembles that observed
1
those seen in the precursor (δ 78.5, J P-C 99.2 Hz, CR;
106.2 br Câ vs 79.1 CR and 108.3 Câ in [Pt(C6F5)2-
(PPh2CtCTol)2]), and a signal observed at δ 153.1 (d,
J P-C ) 57 Hz) is tentatively attributed to the R-C or
â-C atom of the η2-coordinated alkynylphosphine group.
In 7a , four alkyne carbon signals (two alkynyl and two
due to terminal PPh2CtCPh) occur at positions similar

3740 Organometallics, Vol. 21, No. 18, 2002
Fornie´s et al.
(PPh2CtCTol)2] (R ) Ph, tBu) was similar to that described
for cis-[Pt(CtCR)2(PPh2CtCPh)2].7
for 1. These complexes have been shown to bind only
one Pt(PPh3)2 unit, leading to related M(II)-Pt(0) homo
(4, 6, 7) and hetero (Pd-Pt 5) binuclear complexes
stabilized by a κP:η2-PPh2CtCR bridging ligand. The
formation of bimetallic complexes 6 and 7 is remarkable
for several reasons. First bi- or polynuclear complexes
containing terminal alkynyl ligands are rather rare,19
in part due to the strong preference of these groups to
act as bridging ligands. Second, complexation of the low-
valent fragment through the P-bonded PPh2CtCR
ligand indicates that the acetylenic unit on these
molecules exhibits a stronger η2-bonding capability
toward Pt(0) than the alkynyl groups do. This result is
in clear contrast to those previously observed in related
platinum(II) systems in which the alkynyl ligands have
been always found to be the preferred bridging groups.
The lack of reactivity of P-bonded tert-butylalkynylphos-
phine complexes toward [Pt(η2-C2H4)(PPh3)2] confirms
previous observations that indicate the absence or very
low η2-bonding capability of these bulky molecules. The
successful synthesis of complex [(C6F5)2Pt(µ-tht)(µ-1κP:
2η2-PPh2CtCtBu)Pt(C6F5)2], 2c, is likely to be due to
the simultaneous presence of the tetrahydrothiophene
bridging ligand.
Syn th esis of cis-[P t(CtCR)2(P P h 2CtCTol)2] (R ) P h ,
tBu ). A solution of cis-[Pt(CtCPh)2(COD)] (0.590 g, 1.167
mmol) in CH2Cl2 (20 mL) was treated at room temperature
with PPh2CtCTol (0.701 g, 2.334 mmol), and the resulting
solution was stirred for 1 h. The solvent was then removed in
a vacuum, and the addition of cold n-hexane (5 mL) caused
its precipitation as a beige solid, cis-[Pt(CtCPh)2(PPh2Ct
CTol)2] (0.606 g, 52% yield).
cis-[Pt(CtCtBu)2(PPh2CtCTol)2] was prepared similarly
using cis-[Pt(CtCtBu)2(COD)] (0.500 g, 1.07 mmol) and PPh2Ct
CTol (0.645 g, 2.148 mmol) (0.472 g, 46% yield).
Da ta for cis-[P t(CtCP h )2(P P h 2CtCTol)2]. Anal. Calcd
for C58H44P2Pt: C, 69.80; H, 4.44. Found: C, 69.51; H, 4.49.
MS (ES+ ionized with Ag+): m/z 1196 [M + Ag + Tol]+ 35%;
1106 [M + Ag + H]+ 10%; 896 [Pt(C2Ph)(PPh2C2Tol)2]+ 100%.
IR (cm-1): ν(CtC) 2172 (vs), 2123 (s). 1H NMR (CDCl3, 20
°C): δ 7.87 (s, br, 8H); 7.28 (m, 14H); 6.95 (m, 16H) CH, Ph,
Tol; 2.33 (s, CH3). 13C NMR (CDCl3, 20 °C): δ 139.9 (s, C,4
Tol); 133.4 (“t”, J C-P ) 6.3, o-C, PPh2); 131.7 (s, p-C, PPh2);
131.3 (s, Ph); 130.1 (s, Ph); 128.5 (s, CH, Tol); 127.9 (“t”, J C-P
) 5.8, m-C, PPh2); 126.8 (s, CH, Tol); 124.8 (s, Ph); 117.6 (s,
3
3
C1, Tol); 109.2 (AXX′ five line pattern, J C-Ptrans + J C-Pcis
)
+
)
2
36.4, Pt satellites not observed, tCâPh); 108.3 (AXX′, J C-P
2
2
4J C-P ) 15.4, tCâTol); 101.7 (AXX′, dd, J C-Ptrans + J C-Pcis
178.1, Pt-CRt); 80.1 (AXX′, d, J C-P + 3J C-P ) 103.9, -PCRt
1
); 21.4 (s, CH3). 31P NMR (CDCl3, 20 °C): δ -6.39 (s, J Pt-P
)
1
Exp er im en ta l Section
2347).
Da ta for cis-[P t(CtCtBu )2(P P h 2CtCTol)2]. Anal. Calcd
for C54H52P2Pt: C, 67.70; H, 5.47. Found: C, 67.46; H, 5.42.
MS (ES+ ionized with Ag+): m/z 1065 [M + Ag]+ 100%. IR
(cm-1): ν(CtC) 2173 (vs). 1H NMR (CDCl3, 20 °C): δ 7.86 (m,
8H); 7.27 (m, 12H) Ph; 6.93 (AB, J H-H ) 7.8, δA 6.96, δB 6.90,
C6H4); 2.32 (s, CH3); 0.92 (s, tBu). 13C NMR (CDCl3, 20 °C): δ
139.6 (s, C4, Tol); 133.5 (“t”, J C-P ) 6.3, o-C, PPh2); 131.7 (s,
Gen er a l Con sid er a tion s. All reactions and manipulations
were carried out under nitrogen atmosphere using Schlenk
techniques and distilled solvents purified by known proce-
dures. IR spectra were recorded on a Perkin-Elmer FT-IR 1000
spectrometer as Nujol mulls between polyethylene sheets.
NMR spectra were recorded on a Bruker ARX 300 spectrom-
eter; chemical shifts are reported in ppm relative to external
standards (SiMe4, CFCl3, and 85% H3PO4) and coupling
constants in Hz. The low stability or solubility of 2, 3b, 4a , 5,
6, and 7b precluded their characterization by 13C NMR
spectroscopy. Elemental analyses were carried out with a Carlo
Erba EA 1110 CHNS/O microanalyzer; the electrospray mass
spectra on a HP5989B with interphase API-ES HP 59987A
(in the negative ion mode with methanol as the mobile phase);
and the mass spectra (FAB+) on a VG Autospec spectrometer.
PPh2CtCR (R ) Ph,20 Tol,1k tBu20), cis-[Pt(C6F5)2(tht)2],21 [{Pt-
(µ-tht)(C6F5)2}2],22 cis-[Pt(C6F5)2(thf)2],23 cis-[Pt(CtCR)2COD]
(R ) Ph,24 tBu25), cis-[M(C6F5)2(PPh2CtCR)2] (M ) Pt, Pd; R
) Ph,8a Tol8b), and [Pt(η2-C2H4)(PPh3)2]26 were prepared ac-
cording to literature methods. The synthesis of cis-[Pt(CtCR)2-
1
3
p-C, PPh2); 131.6 (AXX′ four lines, J C-P + J C-P ) 54.8, i-C,
PPh2); 129.8 (s, CH, Tol); 128.5 (s, CH, Tol); 127.6 (“t”, J C-P
)
5.8, m-C, PPh2); 117.9 (s, C1, Tol); 116.9 (AXX′ five line pattern,
3J C-Ptrans + 3J C-Pcis ) 35.9, tCâtBu); 107.6 (AXX′, 2J C-P + 4J C-P
2
2
) 14.8, tCâTol); 84.8 (AXX′, dd, J C-Ptrans + J C-Pcis ) 180.1,
Pt-CRt); 80.9 (AXX′, d, J C-P + 3J C-P ) 100.0, P-CRt); 31.5,
31.4 (s, -C(CH3)3); 28.6 (s, J Pt-C ) 21.5, -CMe3); 21.4, 21.3
1
3
1
(s, CH3). 31P NMR (CDCl3, 20 °C): δ -6.19 (s, J Pt-P ) 2319).
Syn th esis of cis-[P t(C6F 5)2(P P h 2CtCR)(th t)] (R ) P h
1a , Tol 1b, tBu 8b 1c). Meth od a . A solution of PPh2CtCPh
(0.101 g, 0.354 mmol) in CH2Cl2 (20 mL) was treated with cis-
[Pt(C6F5)2(tht)2] (0.250 g, 0.354 mmol), and the mixture was
stirred for 1 h. Evaporation to a small volume and addition of
n-hexane (≈5 mL) afforded 1a as a white solid (0.280 g, 87%
yield).
Meth od b. To a white suspension of [{Pt(C6F5)2(µ-tht)}2]
(0.185 g, 0.150 mmol) in CH2Cl2 (10 mL) was added PPh2Ct
CPh (0.086 g, 0.300 mmol). The suspension immediately
dissolved, and the resulting colorless solution (∼1 mL) was
stirred for 1 h. Evaporation to a small volume and addition of
cold EtOH (5-6 mL) caused the precipitation of 1a as a white
solid (0.240 g, 88% yield).
Using a similar procedure complex 1b was prepared with
the appropriate starting materials: PPh2CtCTol (0.106 g,
0.354 mmol) and cis-[Pt(C6F5)2(tht)2] (0.250 g, 0.354 mmol)
(5 h of stirring) (0.253 g, 78% yield) or [{Pt(C6F5)2(µ-tht)}2]
(0.182 g, 0.147 mmol) and PPh2CtCTol (0.088 g, 0.295 mmol)
(0.230 g, 85% yield).
The synthesis of cis-[Pt(C6F5)2(PPh2CtCtBu)(tht)], 1c, using
method a has been previously described.8b 1c can be also
obtained following method b: [{Pt(C6F5)2(µ-tht)}2] (0.178 g,
0.144 mmol) and PPh2CtCtBu (0.077 g, 0.288 mmol) (0.173
g, 68% yield).
(19) (a) Ara, I.; Berenguer, J . R.; Eguiza´bal, E.; Fornie´s, J .; Lalinde,
E. Organometallics 2001, 20, 2686. (b) Berenguer, J . R.; Eguiza´bal,
E.; Falvello, L. R.; Fornie´s, J .; Lalinde, E.; Mart´ın, A. Organometallics
2000, 19, 490. (c) Vaid, T. P.; Veige, A. S.; Lobkousky, E. B.; Glassey,
W. V.; Wolczanski, P. T.; Liable-Sands, L.; Rheingold, A. L.; Cundari,
T. R. J . Am. Chem. Soc. 1998, 120, 10067. (d) Lee, K. E.; Higa, K. T.;
Nissan, R. A.; Butcher, R. J . Organometallics 1992, 11, 2816. (e)
Falvello, L. R.; Fornie´s, J .; Go´mez, J .; Lalinde, E.; Mart´ın, A.; Moreno,
M. T.; Sacrista´n, J . Chem. Eur. J . 1999, 5, 474. (f) Zheng, W.; Mo¨sch-
Zanetti, N. C.; Roesky, H. W.; Hewitt, F. C.; Schneider, T. R.; Stasch,
A.; Prust, J . Angew. Chem., Int. Ed. 2000, 39, 3099. (g) J ime´nez, M.
V.; Sola, E.; Mart´ınez, A. P.; Lahoz, F. J .; Oro, L. A. Organometallics
1999, 18, 1125.
(20) Carty, A. J .; Hota, N. K.; Ng, T. W.; Patel, H. A.; O’Connor, T.
J . Can. J . Chem. 1971, 49, 2706.
(21) Uso´n, R.; Fornie´s, J .; Mart´ınez, F.; Toma´s, M. J . Chem. Soc.,
Dalton Trans. 1980, 888.
(22) Uso´n, R.; Fornie´s, J .; Toma´s, M.; Menjo´n, B.; Navarro, R.;
Carnicer, J . Inorg. Chim. Acta 1989, 162, 33.
(23) Uso´n, R.; Fornie´s, J .; Toma´s, M.; Menjo´n, B. Organometallics
1985, 4, 1912.
(24) Cross, R. J .; Davidson, M. F. J . Chem. Soc., Dalton Trans. 1986,
1987.
(25) Fornie´s, J .; Go´mez-Saso, M. A.; Lalinde, E.; Mart´ınez, F.;
Moreno, M. T. Organometallics 1992, 11, 2873.
Da ta for 1a . Anal. Calcd for C36H23F10PPtS: C, 47.85; H,
2.56; S 3.55. Found: C 47.68; H 2.43; S 3.65. MS (ES+): m/z
(26) Nagel, U. Chem. Ber. 1982, 115, 1998.

Pt(II)-Pt(II) and Pt/ Pd(II)-Pt(0) Bridging Complexes
Organometallics, Vol. 21, No. 18, 2002 3741
926 [M + Na]+ 100%. IR (cm-1): ν(CtC) 2179 (vs); ν(C6F5)X-sens
803 (vs), 786 (s). 1H NMR (CDCl3, 20 °C): δ 7.73-7.41 (m,
(s). 1H NMR (CDCl3, 20 °C): δ 7.66, 7.59, 7.45 (12H); 7.25 (2H)
(CH, Ph, Tol); 3.81 (2H), 3.64 (2H) (s br, R-CH2, tht); 2.42 (s,
CH3); 2.17 (2H), 1.66 (2H) (s, br, â-CH2, tht). 19F NMR (CDCl3,
15H, Ph); 2.89 (s, 4H, R-CH2, tht), 1.71 (s, 4H, â-CH2, tht). 13
C
3
NMR (CDCl3, 20 °C): δ 146.7-136.6 (C6F5); 132.4 (d, J C-P
)
20 °C): δ -117.6 (m, J Pt-o-F ) 365, 2o-F), -118.3 (m, 2o-F);
4
12.9, o-C, PPh2); 132.0 (s, o-C, Ph); 130.9 (d, J C-P ≈ 1, p-C,
PPh2); 130.3 (s, p-C, Ph); 129.1 (d, 1J C-P ) 62, i-C, PPh2); 128.4
(s, m-C, Ph); 128.3 (d, J C-P ) 11.5, m-C, PPh2); 120.2 (d, 3J C-P
-118.6 (m, 2o-F); -119.1 (m, br, 3J Pt-o-F ) 335, 2o-F); -156.7
(t, p-F); -157.6 (t, p-F); -159.1 (t, p-F); -160.9 (m, 4m-F +
1p-F); -163.3 (m, 4m-F). 31P NMR (CDCl3, 20 °C): δ 24.25 (s,
1J Pt-P ) 2359).
2
1
≈ 2.5, i-C, Ph); 108.1 (d, J C-P ) 14.5, tCâPh); 78.6 (d, J C-P
) 98, -PCRt); 36.9 (s, br, R-CH2, tht); 29.6 (s, br, â-CH2-,
Da ta for 2c. Anal. Calcd for C46F20H27PPt2S: C, 39.10; H,
1.93; S, 2.27. Found: C, 38.75; H, 1.72; S, 2.36. MS (FAB+):
m/z 1078 [M - 2C6F5]+ 12%; 894 [Pt(PPh2C2tBu)2(C6F5)]+ 55%;
727 [Pt(PPh2C2tBu)2]+ 87%; 549 [Pt(PPh2C2tBu)(tht)]+ 60%;
461 [Pt(PPh2C2tBu)]+ 75%. IR (cm-1): ν(CtC) 1982 (m, br);
ν(C6F5)X-sens 806 (s, br), 791 (m), 774 (sh). 1H NMR (CDCl3): δ
at 20 °C, 8.05-7.33 (vbr, Ph); 3.77, 3.18 (vbr, R-CH2, tht); 1.92
(vbr, â-CH2, tht); 1.38 (s, 9H, tBu); at -50 °C, 8.04 (s, br, 2H);
7.72-7.30 (m, 8H) Ph; 3.97 (2H), 3.71 (1H), 3.25 (1H) (s, br,
R-CH2, tht); 2.08 (s, br, 2H, â-CH2, tht), the other signal
corresponding to â-CH2 protons could be overlapped with the
signal of tBu group at δ 1.36. 19F NMR (CDCl3): δ at 20 °C,
-117.7 (s, br, 2o-F), -118.2 (s, br, 4o-F); -118.5 (s, br, 2o-F);
-156.6 (t, p-F); -157.5 (t, p-F); -157.9 (t, p-F); -161.0
[overlapping of dt (1p-F and a broad signal due to 3m-F)];
tht). 19F NMR (CDCl3, 20 °C): δ -118.2 (m, J Pt-o-F ≈ 410,
3
290, 4o-F); -160.4 (t, 1p-F); -162.7 (m, 2m-F); -163.1 (t, 1p-
F); -164.5 (m, 2m-F). 31P NMR (CDCl3, 20 °C): δ -5.71 (s,
1J Pt-P ) 2470).
Da ta for 1b. Anal. Calcd for C37H25F10PPtS: C, 48.43; H,
2.75; S, 3.49. Found: C, 48.75; H, 2.25; S, 3.73. MS (FAB+):
m/z 917 [M]+ 7%; 583 [Pt(PPh2C2Tol)(tht)]+ 80%; 495 [Pt-
(PPh2C2Tol)]+ 85%. IR (cm-1): ν(CtC) 2171 (vs); ν(C6F5)X-sens
1
812 (s), 800 (s). H NMR (CDCl3, 20 °C): δ 7.73 (dd, o-H, Ph),
7.42 (m, 8H) (CH, Ph, Tol); 7.20 (d, J H-H ≈ 7.6, 2H, C6H4);
2.89 (s, 4H, R-CH2, tht); 2.40 (s, 3H, CH3); 1.70 (s, 4H, â-CH2,
tht). 13C NMR (CDCl3, 20 °C): δ 147.9-135.0 (C6F5); 140.9 (s,
C4, Tol); 132.4 (d, J C-P ) 12.8, o-C, PPh2); 131.9 (s, CH, Tol);
4
130.8 (d, J C-P ≈ 1, p-C, PPh2); 129.2 (s, CH, Tol); 129.25 (d,
1J C-P ) 62.0, i-C, PPh2); 128.2 (d, J C-P ) 11.5, m-C, PPh2);
117.1 (d, 3J C-P ≈ 2.5, C1, Tol); 108.6 (d, 2J C-P ) 15.0, tCâTol);
CR should appear as a doublet, but one of the peaks overlaps
-161.5 (m, br, 1m-F); -162.6 (m, 2m-F); -163.2 (m, br, 1m-
3
F); -163.5 (m, br, 1m-F); at -50 °C, -116.5 (m, J Pt-o-F
≈
3
360, 1o-F); -117.8 (m, J Pt-o-F ≈ 360, 1o-F); -118.2 (m,
1
3
with the CDCl3 signal (≈77.83, J C-P ≈ 100); 36.9 (s, R-CH2,
1o-F); -118.5 (m, 2o-F); -119.3 (m, 2o-F); -120.3 (m, J Pt-o-F
tht), 29.5 (s, â-CH2, tht); 21.4 (s, CH3, Tol). 19F NMR (CDCl3,
≈ 310, 1o-F); -156.2 (t, 1p-F); -156.9 (t, 1p-F); -157.4 (t,
1p-F); -160.2 (m, 3m-F); -160.5 (t, 1p-F); -160.9 (m,
1m-F); -161.8 (m, 1m-F); -162.2 (m, 1m-F); -162.8 (m,
1m-F); -163.1 (m, 1m-F). 31P NMR (CDCl3, 20 °C): δ 22.09
3
20 °C): δ -118.2 (m, J Pt-o-F ≈ 390, 330, 4o-F); -160.4 (t, 1p-
F); -162.8 (m, 2m-F); -163.2 (t, 1p-F); -164.5 (m, 2m-F). 31P
1
NMR (CDCl3, 20 °C): δ -5.87 (s, J Pt-P ) 2472).
1
1
Da ta for 1c. Analytical, IR, H, 31P, and 19F NMR data for
(s, J Pt-P ) 2332).
this complex have been reported.8b 13C NMR (CDCl3, 20 °C):
Syn th esis of [{(C6F 5)2(th t)P t(µ-1KP :2η2-P P h 2CtCR)}P t-
(P P h 3)2] (R ) P h 3a , Tol 3b). To a solution of cis-[Pt(C6F5)2-
(PPh2CtCPh)(tht)] (0.141 g, 0.156 mmol) in acetone (30 mL)
was added 0.117 g (0.156 mmol) of [Pt(η2-C2H4)(PPh3)2], and
the mixture was stirred at room temperature for 2 h. The
resulting colorless solution was filtered through Celite under
N2 and concentrated to a small volume (3 mL). By addition of
n-hexane (≈10 mL) to the filtrate, complex 3a precipitates as
a white solid (0.140 g, 55% yield).
δ 147.9-135.0 (C6F5); 132.2 (d, J C-P ) 12.8, o-C, PPh2); 130.6
4
1
2
(d, J C-P ) 2.4, p-C, PPh2); 129.8 (d, J C-P ) 62, J Pt-C ) 24,
2
i-C, PPh2); 128.1 (d, J C-P ) 11.5, m-C, PPh2); 119.5 (d, J C-P
) 13.2, tCâtBu); 68.3 (d, 1J CR-P ) 102, P-CRt); 36.8 (d, 3J C-P
) 3, R-CH2, tht); 29.9 (d, 4J C-P ) 1.2, -C(CH3)3); 29.4 (s, â-CH2,
3
tht); 28.6 (d, J C-P ) 1.8, -CMe3).
Syn th esis of [(C6F 5)2P t(µ-th t)(µ-1KP :2η2-P P h 2CtCR)P t-
(C6F 5)2] (R ) P h 2a , Tol 2b, tBu 2c). A general procedure
for 2a is given: a solution of cis-[Pt(C6F5)2(PPh2CtCPh)(tht)],
1a (0.150 g, 0.166 mmol), in CH2Cl2 (20 mL) was treated with
cis-[Pt(C6F5)2(thf)2] (0.112 g, 0.166 mmol), and the colorless
solution was stirred for 1 h. By concentration to a small volume
(≈3 mL) and addition of 5 mL of n-hexane, complex 2a
precipitates as a white solid (0.199 g, 84% yield).
Complex 3b was obtained by reacting an equimolecular
amount to cis-[Pt(C6F5)2(PPh2CtCTol)(tht)] (0.146 g, 0.159
mmol) and [Pt(η2-C2H4)(PPh3)2] (0.119 g, 0.159 mmol) in 30
mL of acetone (2 h). Filtration and evaporation of the reaction
mixture to ca. 3 mL causes the precipitation of 3b as a white
solid in 53% yield (0.139 g).
Complexes 2b and 2c were prepared as white solids follow-
ing a procedure identical to that described for 2a : 0.150 g
(0.163 mmol) of cis-[Pt(C6F5)2(PPh2CtCTol)(tht)], 1b, and
0.110 g (0.163 mmol) of cis-[Pt(C6F5)2(thf)2] (0.200 g, 85% yield);
0.141 g (0.160 mmol) of cis-[Pt(C6F5)2(PPh2CtCtBu)(tht)], 1c,
and 0.108 g (0.160 mmol) of cis-[Pt(C6F5)2(thf)2] (0.116 g, 52%
yield).
Da ta for 3a . Anal. Calcd for C72F10H53P3Pt2S: C, 53.27; H,
3.29; S, 1.97. Found: C, 53.42; H, 3.56; S, 1.50. MS (FAB+):
m/z 1359 [M - PPh3 - 1H]+ 11%; 719 [Pt(PPh3)2]+ 100%. IR
(cm-1): ν(CtC) 1715 (s); ν(C6F5)X-sens 801 (m), 782 (m). 1H
NMR (CDCl3, 20 °C): δ 7.55 (m), 7.47-6.75 (45H) Ph; 1.99
(br, 4H, R-CH2, tht); 1.14 (br, 4H, â-CH2, tht). 13C NMR (CDCl3,
-50 °C): δ 148-137 (C6F5); 135.3-126.3 (Ph), 31.4 (R-CH2,
tht); 29.5 (â-CH2, tht). Signals due to CR and Câ are not
Da ta for 2a . Anal. Calcd for C48F20H23PPt2S: C, 40.24; H,
1.62; S, 2.24. Found: C, 40.14; H, 1.25; S, 2.40. MS (FAB+):
m/z 1432 [M]+ 1%; 1343 [M - tht]+ 1%; 1097 [M - 2C6F5]+
1%. IR (cm-1): ν(CtC) 2051 (w), 2006 (m); ν(C6F5)X-sens 805
(s, br). 1H NMR (CDCl3, 20 °C): δ 7.66 (m, 8H), 7.47 (s, br,
7H) Ph; 3.82 (2H), 3.64 (2H) (s, br, R-CH2, tht); 1.67 (2H), 1.55
(2H) (s, br, â-CH2, tht). 19F NMR (CDCl3, 20 °C): δ -117.6
3
observed. 19F NMR (CDCl3, 20 °C): δ -117.4 (m, J Pt-o-F
)
3
280, 2o-F); -118.0 (m, J Pt-o-F ) 430, 2o-F); -161.8 (t, 1p-F);
-163.5 (m, 2m-F); -165.3 (m, 1p-F + 2m-F).
Da ta for 3b. Anal. Calcd for C73F10H55P3Pt2S: C, 53.55; H,
3.38; S, 1.96. Found: C, 53.78; H, 3.56; S, 1.27. MS (FAB+):
m/z 1380 [M - tht - C6F5 - 1H]+ 4.2%; 757 [Pt(PPh3)(PPh2C2-
Tol)]+ 10%; 719 [Pt(PPh3)2]+ 100%. IR (cm-1): ν(CtC) 1714
3
(m, J Pt-o-F ≈ 370, 2o-F); -118.3 (m, 2o-F); -118.6 (m, 2o-F);
3
1
-119.2 (m, br, J Pt-o-F ≈ 340, 2o-F); -156.5 (t, p-F); -157.5
(s, br); ν(C6F5)X-sens 800 (m), 793 (m). H NMR (CDCl3, 20 °C):
(t, p-F); -158.9 (t, p-F); -160.8 (m, 4m-F + p-F); -163.2 (m,
δ 7.53 (m, 6H); 7.23-6.65 (m, 38H) (CH, Ph, Tol); 2.12 (s, CH3);
1.98 (br, 4H, R-CH2, tht); 1.16 (br, 4H, â-CH2, tht). 19F NMR
(CDCl3, 20 °C): δ -117.4 (m, 3J Pt-o-F ) 329, 2o-F); -118.0 (m,
3J Pt-o-F ) 425, 2o-F); -161.9 (t, 1p-F); -163.6 (m, 2m-F);
-165.3 (m, 1p-F + 2m-F).
1
4m-F). 31P NMR (CDCl3, 20 °C): δ 24.25 (s, J Pt-P ) 2349).
Da ta for 2b. Anal. Calcd for C49F20H25PPt2S: C, 40.68; H,
1.74; S, 2.22. Found: C, 40.80; H, 1.47; S, 2.45. MS (FAB+):
m/z 1358 [M - tht]+ 1%; 1111 [M - 2C6F5 - 1H]+ 2%; 829
[Pt(C6F5)2(PPh2C2Tol)]+ 5%; 662 [Pt(C6F5)(PPh2C2Tol)]+ 6%;
583 [Pt(PPh2C2Tol)(tht)]+ 10%; 495 [Pt(PPh2C2Tol)]+ 8%. IR
(cm-1): ν(CtC) 2059 (w), 2017 (m); ν(C6F5)X-sens 815 (m), 804
Syn th esis of cis-[{(C6F 5)2M(P P h 2CtCR)(µ-1KP :2η2-
P P h 2CtCR)}P t(P P h 3)2] (M ) P t, R ) P h 4a , Tol 4b; M )
P d , R ) P h 5a , Tol 5b). Syn th esis of 4a . A solution of cis-

3742 Organometallics, Vol. 21, No. 18, 2002
Fornie´s et al.
[Pt(C6F5)2(PPh2CtCPh)2] (0.166 g, 0.151 mmol) in 10 mL of
acetone was treated with [Pt(η2-C2H4)(PPh3)2] (0.136 g, 0.181
mmol) (molar ratio 1:1.2) at room temperature, and after 15
min of stirring, a white solid started to precipitate. The
suspension was stirred for 1 h, and then the solid was filtered
and washed with acetone (0.173 g, 61% yield). 4a crystallizes
with one molecule of CH3COCH3.
Syn th esis of 4b. A solution of cis-[Pt(C6F5)2(PPh2CtCTol)2]
(0.188 g, 0.167 mmol) in 30 mL of acetone was treated with
[Pt(η2-C2H4)(PPh3)2] (0.149 g, 0.200 mmol) (molar ratio 1:1.2),
and the mixture was stirred for 2 h. The resulting turbid, pale
yellow solution was filtered through Celite and the filtrate
evaporated to dryness. The residue was treated with cold
diethyl ether (≈5 mL), yielding complex 4b (0.188 g, 61% yield)
as a white solid. When the reaction was carried out in a molar
ratio 1:2, only product 4b was obtained (82% yield).
Syn th esis of 5a a n d 5b. Complexes 5a and 5b were
prepared as white solids following a procedure identical to that
described for 4b, using the corresponding starting materials.
5a : cis-[Pd(C6F5)2(PPh2CtCPh)2] (0.167 g, 0.165 mmol) and
[Pt(η2-C2H4)(PPh3)2] (0.148 g, 0.198 mmol) (0.188 g, 66% yield).
5b: cis-[Pd(C6F5)2(PPh2CtCTol)2] (0.175 g, 0.168 mmol) and
[Pt(η2-C2H4)(PPh3)2] (0.151 g, 0.200 mmol) (0.198 g, 67% yield).
The NMR spectra of 4 and 5 always show trace amounts of
the corresponding cis-bis(alkynylphosphine) precursors. How-
ever, attempts to recrystallize these products caused the loss
of the Pt(PPh3)2 fragment, yielding solids that contained higher
amounts of the corresponding mononuclear starting deriva-
tives.
COCD3): δ 7.57-6.74 (58H, Ph); 2.51, 2.22 (s, CH3). 19F NMR
(CD3COCD3): δ at -50 °C, -109.7 (m, 2o-F); -112.1 (s, br,
1o-F); -114.8 (s, br, 1o-F); -162.0 (t, 1p-F); -162.45 (br,
1m-F); -163.15 (br, 1m-F); -163.35 (t, 1p-F); -164.0 (m,
2m-F); at 20 °C, -110.8 (s, br, 2o-F); -112.2 (vbr, 2o-F); -163.0
(t, 1p-F); -163.9 (br, 2m-F); -164.0 (t, 1p-F); -164.4 (m,
2m-F).
Syn th esis of cis-[{(CtCR′)2P t(P P h 2CtCR)(µ-1KP :2η2-
P P h 2CtCR)}P t(P P h 3)2] (R′ ) P h , R ) P h 6a , Tol 6b; R′ )
tBu , R ) P h 7a , Tol 7b). A solution of cis-[Pt(CtCPh)2-
(PPh2CtCPh)2] (0.159 g, 0.164 mmol) in acetone (20 mL) was
treated with [Pt(η2-C2H4)(PPh3)2] (0.147 g, 0.197 mmol) (molar
ratio 1:1.2), and the reaction mixture was stirred at room
temperature for 2 h. The resulting light brown solution was
filtered through Celite and evaporated to dryness. The residue
was treated with a cold mixture of diethyl ether/hexane (1:2),
yielding complex 6a as a pale yellow solid (0.194 g, 70% yield).
Complexes 6b and 7b (light brown) were prepared similarly
to 6a , starting from cis-[Pt(CtCPh)2(PPh2CtCTol)2] (0.159 g,
0.160 mmol) and [Pt(η2-C2H4)(PPh3)2] (0.143 g, 0.192 mmol)
(0.205 g, 75% yield), or cis-[Pt(CtCtBu)2(PPh2CtCTol)2] (0.168
g, 0.175 mmol) and [Pt(η2-C2H4)(PPh3)2] (0.158 g, 0.211 mmol)
(0.194 g, 67%).
Complex 7a was prepared as a pale yellow solid following a
similar procedure, using cis-[Pt(CtCtBu)2(PPh2CtCPh)2] (0.162
g, 0.174 mmol) and [Pt(η2-C2H4)(PPh3)2] (0.155 g, 0.208 mmol),
by evaporation to a small volume (≈2 mL) of the acetone
solution (0.198 g, 69% yield).
Da ta for 6a . Anal. Calcd for C92H70P4Pt2: C, 65.16; H, 4.12.
Found: C, 64.76; H, 4.50. MS (FAB+): m/z 1689 [M]+ 3%; 1427
[M - PPh3]+ 28%; 1325 [M - PPh3 - C2Ph]+ 20%; 1224 [M -
PPh3 - 2(C2Ph)]+ 57%; 1123 [M - PPh3 - 3(C2Ph)]+ 17%; 719
[Pt(PPh3)2]+ 80%. IR (cm-1): ν(CtC) 2174 (m), 2121 (m), 1743
(sh), 1705 (m, br). 1H NMR (CD3COCD3): δ 7.10 (m, 70H, Ph).
Da ta for 6b. Anal. Calcd for C94H74P4Pt2: C, 65.73; H, 4.34.
Found: C, 66.08; H, 4.65. MS (FAB+): (%) 1215 [M - 2(C2Ph)
- PPh2C2Tol + 1H]+ 24%; 719 [Pt(PPh3)2]+ 67%. IR (cm-1):
ν(CtC) 2173 (m), 2123 (m), 1760 (sh), 1715 (m). 1H NMR
(CDCl3, 20 °C): δ 7.87-6.28 (68 H, Ph); 2.29, 2.07 (s, CH3).
Da ta for 7a . Anal. Calcd for C88H78P4Pt2: C, 64.07; H, 4.77.
Found: C, 63.98; H, 4.64. MS (FAB+): m/z 1647 [M - 2H]+
2%; 1386 [M - PPh3]+ 3%; 1306 [M - PPh3 - C2tBu + 1H]+
Da ta for 4a ‚CH3COCH3. Anal. Calcd for C88F10H60P4-
Pt2.C3H6O: C, 58.15; H, 3.54. Found: C, 58.19; H, 3.24. MS
(FAB+): m/z peak molecular not observed; 718 [Pt(PPh3)2 -
1H]+ 53%. IR (cm-1): ν(CtC) 2177 (s), 1756 (vs); ν(C6F5)X-sens
792 (m), 778 (m); a medium band at 1716 cm-1 probably due
to CH3COCH3 is also observed. 1H NMR (CDCl3, 20 °C): δ
7.58-6.57 (m, 60H, Ph). 19F NMR (CDCl3): δ at -50 °C,
-113.4 (s, br, 1o-F); -113.8 (s, br, 3J Pt-o-F ≈ 360, 1o-F); -116.5
3
(s, br, J Pt-o-F ) 302, 1o-F); -119.5 (s, br, 1o-F); -162.4 (t,
1p-F); -163.2 (m, 1m-F); -163.8 (m, 1p-F, 1m-F); -164.3 (m,
1m-F); -164.8 (m, 1m-F); at 20 °C, -115.4 (vbr, o-F); -163.3
(t, 1p-F); -164.3 (t, 1p-F); -164.6 (m, br, 4m-F).
Da ta for 4b. Anal. Calcd for C90F10H64P4Pt2: C, 58.45; H,
3.49. Found: C, 58.56; H, 3.58. MS (ES+ ionized with Ag+):
m/z 1957 [M + Ag]+ 100%; 1694 [M + Ag - PPh3]+ 18%; 1656
[M + Ag - PPh2C2Tol]+ 36%. IR (cm-1): ν(CtC) 2177 (s), 1691
(m); ν(C6F5)X-sens 791 (m), 778 (m). 1H NMR (CD3COCD3, 20
°C): δ 7.61-6.72 (58H, Ph); 2.50, 2.20 (s, CH3). 13C NMR (CD3-
COCD3, -50 °C): δ 153.1 (d, J P-C ) 57 Hz, CR or CΒ, η2-Ct
CTol); 146.4-137.4 (C6F5); 140.4 (s, C4, Tol); 135.6-126.5
(aromatics); 117.73, 117.70 (s, C1, Tol); 106.2 (br, Câ, tCâTol);
78.5 (J C-P ) 99.2, CR, -PCRt); 20.7, 20.5 (s, CH3). 19F NMR
3.5%; 1224 [M - PPh3 - 2(C2tBu)]+ 10%; 1123 [M - PPh3
-
2(C2tBu) - C2Ph]+ 10%; 1022 [M - PPh3 - 2(C2tBu) - 2(C2-
Ph)]+ 10%; 719 [Pt(PPh3)2]+ 75%. IR (cm-1): ν(CtC) 2175 (m),
1748 (sh), 1705 (m, br). 1H NMR (CDCl3, 20 °C): δ 7.96, 7.49-
6.34, 6.13 (br, 60 H, Ph); 1.16, 1.10 (s, 9H, tBu). 13C NMR (CD3-
COCD3): δ at -50 °C, 136.3-126.1, 123.6 (s), 120.98 (s)
(phenyl resonances); 115.0 (dd, 2J C-Ptrans/2J C-Pcis ≈ 240/33, Pt-
2
CR); 106.6 (d, J C-P ) 11.9, tCâPh); 87.0 (pst, J C-P ≈ 18.4, t
CâtBu); 81.0 (dm, 1J C-P ≈ 85, -PCRt); 32.2, 31.5 (s, -C(CH3)3);
3
(CD3COCD3): δ at -50 °C, -112.4 (s, br, J Pt-o-F ≈ 285, 2o-
29.0, 28.8 (s, -CMe3).
3
F); -115.0 (s, br, J Pt-o-F ≈ 310, 1o-F); -117.5 (br, 1o-F);
Da ta for 7b. Anal. Calcd for C90H82P4Pt2: C, 64.43; H, 4.93.
Found: C, 64.40; H, 4.57. MS (FAB+): m/z 1678 [M + 1H]+
5%; 1416 [M - PPh3 + 2H]+ 11%; 1335 [M - PPh3 - C2tBu +
2H]+ 12%; 1254 [M - PPh3 - 2C2tBu + 2H]+ 26%; 1138 [M -
PPh3 - 2C2tBu - C2Tol + 1H]+ 19%; 719 [Pt(PPh3)2]+ 100%.
-162.8 (t, 1p-F); -163.3 (br, 1m-F); -163.8 (br, 1m-F); -164.2
(t, 1p-F); -164.7 (m, br, 2m-F); at 20 °C, -113.5, -114.8 (vbr,
o-F); -163.9 (t, 1p-F); -164.9 (m, 1p-F, m-F).
Da ta for 5a . Anal. Calcd for C88F10H60P4PdPt: C, 61.00;
H, 3.49. Found: C, 61.11; H, 3.59. MS (FAB+): m/z 1446 [M
- PPh2C2Ph]+ 13%; 719 [Pt(PPh3)2]+ 100%. IR (cm-1): ν(Ct
1
IR (cm-1): ν(CtC) 2174 (m), 1751 (sh), 1713 (m, br). H NMR
(CD3COCD3, 20 °C): δ 7.90-6.30 (m, 58H, Ph); 2.30, 2.26 (s,
CH3); 1.16, 1.04 (s, 9H, tBu).
1
C) 2174 (s), 1753 (s), 1716 (sh); ν(C6F5)X-sens 778 (m). H NMR
(CD3COCD3, 20 °C): 7.70-6.76 (60H, Ph). 19F NMR (CD3-
COCD3): δ at -50 °C, -109.4 (m, 2o-F); -112.4 (s, 1o-F);
-115.3 (s, br, 1o-F); -162.0 (t, 1p-F); -162.3 (m, 1m-F); -163.3
(m, 1m-F); -163.4 (t, 1p-F); -164.0 (m, 2m-F); at 20 °C, -110.9
(vbr); -112.4 (vbr) o-F; -163.0 (t, 1p-F); -163.4 (vbr, m-F);
-164.0 (m, 1p-F); -164.3 (vbr, m-F).
Da ta for 5b. Anal. Calcd for C90F10H64P4PdPt: C, 61.39;
H, 3.66. Found: C, 61.85; H, 3.92. MS (ES+ ionized with
Ag+): 1869 [M + Ag]+ 3%; 1593 [M - C6F5]+ 38%; 1292 [M -
C6F5 - PPh2C2Tol]+ 100%. IR (cm-1): ν(CtC) 2176 (s), 1746
(sh), 1712 (m); ν(C6F5)X-sens 776 (m, br). 1H NMR (CD3-
Cr yst a l St r u ct u r e Det er m in a t ion s for 2a a n d 3a .
Crystals of 2a and 3a suitable for X-ray analysis were obtained
by slow diffusion of n-hexane into a CH2Cl2 solution of 2a or
3a , respectively. The diffraction measurements were made on
a NONIUS Kappa CCD diffractometer, using graphite-mono-
chromated Mo KR radiation. An empirical absorption correc-
tion using SCALEPACK was applied.27 All calculations were
carried out using the SHELXL-97 program.28 The structures
were solved by direct methods and refined on F2. All non-
(27) Otwinowski, Z.; Minor, W. Methods Enzymol. 1996, 276A, 307.

Pt(II)-Pt(II) and Pt/ Pd(II)-Pt(0) Bridging Complexes
Organometallics, Vol. 21, No. 18, 2002 3743
Ta ble 4. Cr ysta l Da ta a n d Str u ctu r e Refin em en t for 2a ‚0.5C6H14 a n d 3a ‚CH2Cl2
2a ‚0.5C6H14
3a ‚CH2Cl2
empirical formula
fw
C
48F20H23PPt2S‚C3H7
C
72F10H53P3Pt2S‚CH2Cl2
1475.96
1708.22
temperature (K)
cryst syst, space group
unit cell dimens, a (Å)
b (Å)
293(2)
150(1)
triclinic, P1h
12.5657(1)
14.0831(2)
20.0108(3)
105.4814(7)
93.3360(8)
108.2565(6)
3201.78(7)
triclinic, P1h
12.4059(2)
13.3668(2)
14.7789(3)
89.2974(5)
84.6206(5)
83.6718(6)
2425.08(7)
2, 2.021
c (Å)
R (deg)
â (deg)
γ (deg)
volume (Å3)
Z, Dcalcd (Mg/m3)
2, 1.772
4.629
abs coeff (mm-1
)
5.953
F(000)
1406
1668
θ range for data collection (deg)
no. of data/restraints/params
goodness-of-fit on F2
4.12 to 26.50
9976/0/659
1.261
1.73 to 28.06
15251/0/820
1.371
final R indices [I > 2σ(I)]
R1 ) 0.0309, wR2 ) 0.0707
R1 ) 0.0460, wR2 ) 0.0748
1.390 and -0.816
R1 ) 0.0318, wR2 ) 0.0770
R1 ) 0.0400, wR2 ) 0.0800
1.547 and -2.028
R indices (all data)
largest diff peak and hole (e‚Å-3
)
hydrogen atoms were located in succeeding difference Fourier
syntheses and refined with anisotropic thermal parameters.
All hydrogen atoms were constrained to idealized geometries
with isotropic displacement parameters equal to 1.2-1.5 times
the Uiso value of their attached carbon. There are peaks of
electron density higher than 1 e/Å3 in the final map, but they
are located very close to the platinum atoms and have no
chemical meaning. Complex 2a crystallizes with a half mol-
ecule of n-hexane and 3a with a molecule of CH2Cl2. Some
crystallographic details are shown in Table 4.
Ack n ow led gm en t. We wish to thank the Direccio´n
General de Ensen˜anza Superior (Spain Projects PB98-
1595-C02-01, 02) and the University of La Rioja (Project
API-01/B20) for their financial support.
Su p p or tin g In for m a tion Ava ila ble: Further details of
the structure determination of 2a ‚0.5C6H14 and 3a ‚CH2Cl2,
including atomic coordinates, bond distances and angles, and
thermal parameters. This material is available free of charge
via the Internet at http://pubs.acs.org
(28) Sheldrick, G. M. SHELX-97, a program for the refinement of
crystal structures; University of Go¨ttingen: Germany, 1997.
OM020374W