Synthesis and reactivity of σ-alkynyl/P-bonded phosphinoalkyne platinum complexes toward cis-[M(C6F5)2(thf)2] (M = Pt, Pd)

Article abstract of DOI:10.1021/om970663y

The reactivity of cis-bis(alkynyl)bis((diphenylphosphino)alkyne)platinum(II) complexes cis-[Pt(C≡CR)₂L₂] (R = Ph, Bu^t; L = PPh₂C≡CPh (L¹), PPh₂C≡CBu^t (L²); 1-4), formed by displacement of the COD ligand from [Pt(C≡CR)₂(COD)], toward cis-[M(C₆F₅)₂(thf)₂] (M = Pt, Pd, thf = tetrahydrofuran; in both a 1:1 and 1:2 molar ratio) has been investigated. Treatment of 1-4 with 1 equiv of cis-[M(C₆F₅)₂(thf)₂] affords dinuclear derivatives [{L₂Pt-(μ-η¹:η²-C≡CR) ₂}M(C₆F₅)₂] (5-12) with exclusive formation of doubly alkynyl-bridged systems. The molecular structure of [{(Bu^tC≡CPh₂P)₂Pt(μ-η ¹:η²-C≡CPh)₂}Pd(C₆F ₅)₂], 10, is presented. In contrast, it was found that the course of the reactions with 2 equiv of cis-[M(C₆F₅)₂(thf)₂] strongly depend on the alkynyl substituents and metal centers. Thus, treatment of tert-butylalkynyl derivatives cis-[Pt(C≡CBu^t)₂L₂] (2, 4) with 2 equiv of cis-[M(C₆F₅)₂(thf)₂] (M = Pt, Pd) only gives the expected trinuclear complexes 15A and 18A, in the case of the reactions with cis-[Pt(C₆F₅)₂(thf)₂]. The molecular structure of the complex [{Pt(μ-κ(P):η²-PPh₂C≡CPh) ₂(μ-η¹:η²-C≡CBu ^t)₂}{Pt(C₆F₅)₂} ₂], 15A, reveals that both the complexed cis-Pt(C₆F₅)₂ moieties are symmetrically linked to the precursor "cis-[Pt(C≡CBu^t)₂-(PPh ₂C≡CPh)₂]", with the platinum atoms connected by two unusual mixed alkynyl/ phosphinoalkyne bridging systems. On the other hand, similar reactions of phenylethynyl derivatives (1, 3) with 2 equiv of cis-[Pd(C₆F₅)₂(thf)₂] and 3 (L = PPh₂C≡CBu^t) with cis-[Pt-(C₆F₅)₂(thf)₂] lead, instead, to the unexpected trinuclear PtPd₂ (14B, 17B) and Pt₃ (16B) derivatives which display terminal phosphinoalkyne ligands and, hence, contain the alkynyl groups acting as μ₃-η² (σ-Pt edge Pd or Pt) bridging ligands. However, a mixture of both types of isomers 13A and 13B (50:32) is observed in the reaction system cis-[Pt(C≡CPh)₂-(PPh₂C≡CPh)₂] (1)/cis-[Pt(C₆F₅)₂(thf)₂]. The following order of bonding capability is deduced from this study: alkynyl > P-bonded phosphinoalkyne and XC≡CPh fragments > XC≡CBu^t (X = Pt, P).

Full text of DOI:10.1021/om970663y

Organometallics 1997, 16, 5923-5937
5923
Syn th esis a n d Rea ctivity of σ-Alk yn yl/P -Bon d ed
P h osp h in oa lk yn e P la tin u m Com p lexes tow a r d
cis-[M(C6F 5)2(th f)2] (M ) P t, P d )†
Irene Ara,‡ Larry R. Falvello,‡ Susana Ferna´ndez,§ J uan Fornie´s,*,‡
Elena Lalinde,*,§ Antonio Mart´ın,‡ and M. Teresa Moreno‡
Departamento de Qu´ımica Inorga´nica, Instituto de Ciencia de Materiales de Arago´n,
Universidad de Zaragoza-Consejo Superior de Investigaciones Cient´ıficas,
50009 Zaragoza, Spain, and Departamento de Qu´ımica, Universidad de La Rioja,
26001 Logron˜o, Spain
Received J uly 31, 1997X
The reactivity of cis-bis(alkynyl)bis((diphenylphosphino)alkyne)platinum(II) complexes cis-
[Pt(CtCR)2L2] (R ) Ph, But; L ) PPh2CtCPh (L1), PPh2CtCBut (L2); 1-4), formed by
displacement of the COD ligand from [Pt(CtCR)2(COD)], toward cis-[M(C6F5)2(thf)2] (M )
Pt, Pd, thf ) tetrahydrofuran; in both a 1:1 and 1:2 molar ratio) has been investigated.
Treatment of 1-4 with 1 equiv of cis-[M(C6F5)2(thf)2] affords dinuclear derivatives [{L2Pt-
(µ-η1:η2-CtCR)2}M(C6F5)2] (5-12) with exclusive formation of doubly alkynyl-bridged
systems. The molecular structure of [{(ButCtCPh2P)2Pt(µ-η1:η2-CtCPh)2}Pd(C6F5)2], 10,
is presented. In contrast, it was found that the course of the reactions with 2 equiv of cis-
[M(C6F5)2(thf)2] strongly depend on the alkynyl substituents and metal centers. Thus,
treatment of tert-butylalkynyl derivatives cis-[Pt(CtCBut)2L2] (2, 4) with 2 equiv of cis-
[M(C6F5)2(thf)2] (M ) Pt, Pd) only gives the expected trinuclear complexes 15A and 18A, in
the case of the reactions with cis-[Pt(C6F5)2(thf)2]. The molecular structure of the complex
[{Pt(µ-κ(P):η2-PPh2CtCPh)2(µ-η1:η2-CtCBut)2}{Pt(C6F5)2}2], 15A, reveals that both the
complexed cis-Pt(C6F5)2 moieties are symmetrically linked to the precursor “cis-[Pt(CtCBut)2-
(PPh2CtCPh)2]”, with the platinum atoms connected by two unusual mixed alkynyl/
phosphinoalkyne bridging systems. On the other hand, similar reactions of phenylethynyl
derivatives (1, 3) with 2 equiv of cis-[Pd(C6F5)2(thf)2] and 3 (L ) PPh2CtCBut) with cis-[Pt-
(C6F5)2(thf)2] lead, instead, to the unexpected trinuclear PtPd2 (14B, 17B) and Pt3 (16B)
derivatives which display terminal phosphinoalkyne ligands and, hence, contain the alkynyl
groups acting as µ3-η2 (σ-Pt edge Pd or Pt) bridging ligands. However, a mixture of both
types of isomers 13A and 13B (50:32) is observed in the reaction system cis-[Pt(CtCPh)2-
(PPh2CtCPh)2] (1)/cis-[Pt(C6F5)2(thf)2]. The following order of bonding capability is deduced
from this study: alkynyl > P-bonded phosphinoalkyne and XCtCPh fragments > XCtCBut
(X ) Pt, P).
In tr od u ction
seems to require a low-valent metal site with a high
affinity for alkyne π-electrons.2,3 These bonding situ-
ations are well represented by the low-valent dinuclear
complexes [Fe2(µ-η3-PPh2CtCPh)2(CO)6],3c [Ni2(µ-η3-
PPh2CtCBut)2(CO)2],3f [M2(µ-η3-PPh2CtCPh)2(PPh3)2]
(M ) Pt, Pd)3g (Scheme 1, A), and [Fe2(µ-η3-PPh2Ct
CBut)(CO)8]3d (Scheme 1, B), in which the PPh2CtCR
groups act as four-electron bridging ligands (P, η2) and
by the tetranuclear [Co4(µ3-η3-PPh2CtCR)2(CO)10]3a and
trinuclear [Ni2Cp2(µ3-η3-PPh2CtCPh)Ni(CO)3]2b deriva-
tives in which the ligands behave as six-electron donors
(P, η2:η2, Scheme 1, C). In this context, we have recently
shown that the reaction of cis-[MCl2(PPh2CtCPh)2] (M
) Pt, Pd) with cis-[Pt(C6F5)2(thf)2] gives the unusual
dinuclear derivatives [(C6F5)2Pt(µ-Cl)(µ-η3-PPh2CtCPh)-
MCl(PPh2CtCPh)]4 (Scheme 1, D) containing a diphen-
Phosphinoalkynes and acetylides have been widely
used in the formation of organometallic complexes con-
taining two or more transition metals. Phosphino-
alkynes (PPh2CtCR) are potentially difunctional ligands
with the capacity to coordinate as simple phosphines1
or disubstituted acetylenes2 or to simultaneously use the
phosphorus lone pair and the acetylenic π-orbitals in a
polydentate bonding mode.3 Although all three of these
possibilities have been observed, it seems that the
coordinating ability of PPh2CtCR is usually dominated
by the phosphine donor sites, especially for complexes
of metals in their normal oxidation states. The partici-
pation of the acetylenic triple bonds in coordination
† Dedicated to Prof. Pascual Royo on the occasion of his 60th
birthday.
‡ Universidad de Zaragoza.
(3) (a) Hota, N. K.; Patel, H. A.; Carty, A. J .; Mathew, M.; Palenik,
G. J . J . Organomet. Chem. 1971, 32, C55. (b) Sappa, E.; Predieri, G.;
Tiripicchio, A.; Tiripicchio-Camelini, M. J . Organomet. Chem. 1985,
297, 103. (c) Carty, A. J .; Paik, H. N.; Palenik, G. J . Inorg. Chem. 1977,
16, 300. (d) Carty, A. J .: Smith, W. F.; Taylor, N. J . J . Organomet.
Chem. 1978, 146, C1. (e) O’Connor, T.; Carty, A. J .; Mathew, M.;
Palenik, G. J . J . Organomet. Chem. 1972, 38, C15. (f) Carty, A. J .;
Dymock, K.; Paik, H. N.; Palenik, G. J . J . Organomet. Chem. 1974,
70, C17. (g) J acobsen, S.; Carty, A. J .; Mathew, M.; Palenik, G. J . J .
Am. Chem. Soc. 1974, 96, 4330.
§ Universidad de La Rioja.
X Abstract published in Advance ACS Abstracts, December 1, 1997.
(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.
(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.
S0276-7333(97)00663-8 CCC: $14.00 © 1997 American Chemical Society

5924 Organometallics, Vol. 16, No. 26, 1997
Ara et al.
Sch em e 1
yl(phenylethynyl)phosphine acting as a bridging ligand
(µ-P:η2) between two Pt(II) centers. The formation of
these derivatives is rather surprising since the isomeric
dinuclear doubly bridging chloride complexes [(C6F5)2-
Pt(µ-Cl)2M(PPh2CtCPh)2] would have been expected.
Interestingly, we observed that these complexes D,
which are sparingly soluble in common organic solvents,
dissolve in CD2Cl2, yielding a mixture of the isomers D
along with the expected M(µ-Cl)2Pt derivatives. This
fact suggests that in solution the migration of the Pt-
(C6F5)2 unit around the cis-PtCl2(PPh2CtCPh)2 frag-
ment [µ-Cl, κ(P):η2] f (µ-Cl)2 probably has a small
energetic cost and that steric effects involving the two
mutually cis bulky PPh2CtCPh groups should account
in part for the µ-η3-PPh2CtCPh bridging preference in
the solid phase.
trinuclear compounds stabilized with double alkynyl
bridges, Pt(µ-CtCR)2M.5a,6
In this paper, we report on the synthesis of neutral
cis-bis(alkynyl)bis((diphenylphosphino)alkyne)platinum-
(II) complexes cis-[Pt(CtCR)2L2] (R ) Ph, But; L )
PPh2CtCPh, PPh2CtCBut) and describe their reactiv-
ity toward cis-[M(C6F5)2(thf)2] (M ) Pt, Pd) in either a
1:1 or 1:2 molar ratio. The syntheses of both di- and
trinuclear complexes and the solid-state structures of
[{(ButCtCPh2P)2Pt(µ-η1:η2-CtCPh)2}Pd(C6F5)2], 10, an
unusual triplatinum [{Pt(µ-κ(P):η2-PPh2CtCPh)2(µ-η1:
η2-CtCBut)2}{Pt(C6F5)2}2], 15A, and an unprecedented
triangular trimetallic bicapped [{(PPh2CtCBut)2Pt(µ3-
η2-CtCPh)2}{Pt(C6F5)2}2] complex, 16B, are presented.
Resu lts a n d Discu ssion
On the other hand, the ability of alkynyl ligands to
bind several metal centers through σ and π bonds is now
firmly established.5 In particular, we have recently
found that either neutral or anionic alkynylplatinum
substrates [LnM(CtCR)2]n- (n ) 0, L ) phosphine,
COD; n ) 2, L ) C6F5, CtCR) react with Lewis-acidic
metal complexes yielding homo- and hetero- di- and
Syn th eses of cis-[P t(CtCR)2L2] Com p lexes.
A
series of stable mononuclear σ-alkynyl/P-coordinated
(diphenylphosphino)alkyne complexes cis-[Pt(CtCR)2L2]
(R ) Ph or But; L ) PPh2CtCPh (L1), PPh2CtCBut (L2);
1-4) are easily prepared in high yield by displacement
of the weakly coordinating COD ligand from [Pt-
(CtCR)2COD] (R ) Ph, But) derivatives by the ap-
propriate diphenylalkynylphosphine ligands (eq 1).
They are isolated as white solids, and their spectroscopic
data (Tables 1 and 2) unequivocally confirm the P-
coordination mode of the difunctional PPh2CtCR
(4) Fornie´s, J .; Lalinde, E.; Mart´ın, A.; Moreno, M. T.; Welch, A. J .
J . Chem. Soc., Dalton Trans. 1995, 1333.
(5) (a) Fornie´s, J .; Lalinde, E. J . Chem. Soc., Dalton Trans. 1996,
2587. (b) Beck, W.; Niemer, B.; Wieser, M. Angew. Chem., Int. Ed. Engl.
1993, 32, 923. (c) Lotz, S.; Van Rooyen, P. H.; Meyer, R. Adv.
Organomet. Chem. 1995, 37, 219 and references therein. (c) Nast, R.
Coord. Chem. Rev. 1982, 47, 89. (d) Carty, A. J . Pure Appl. Chem. 1982,
54, 113. (e) Bruce, M. I. Pure Appl. Chem. 1986, 58, 553; 1990, 6, 1021.
(f) Raithby, P. R.; Rosales, M. J . Adv. Inorg. Chem. Radiochem. 1985,
29, 169. (g) Sappa, E.; Tiripicchio, A.; Braunstein, P. Coord. Chem.
Rev. 1985, 65, 219. (h) Bruce. M. I. Chem. Rev. 1991, 91, 197. (i) Davies,
S. G.; McNally, J . P.; Smallridge, A. J . Adv. Organomet. Chem. 1990,
30, 1. (j) Pavan Kumar, P. N. V.; J emmis, E. D. J . Am. Chem. Soc.
1988, 110, 125. (k) J eannin, Y. Transition Met. Chem. 1993, 18, 122.
(l) Cauletti, C.; Furlani, C.; Sebald, A. Gazz. Chim. Ital. 1988, 118, 1.
(6) (a) Fornie´s, J .; Go´mez-Saso, M. A.; Lalinde, E.; Mart´ınez, F.;
Moreno, M. T. Organometallics 1992, 11, 2873. (b) Fornie´s, J .; Lalinde,
E.; Mart´ın, A.; Moreno, M. T. J . Chem. Soc., Dalton Trans. 1994, 135.
(c) Berenguer, J . R.; Fornie´s, J .; Lalinde, E.; Mart´ınez, F. J . Organomet.
Chem. 1994, 470, C15. (d) Berenguer, J . R.; Fornie´s, J .; Lalinde, E.;
Mart´ınez, F. J . Chem. Soc., Chem. Commun. 1995, 1227. (e) Fornie´s,
J .; Lalinde, E.; Mart´ın, A.; Moreno, M. T. J . Organomet. Chem. 1995,
490, 179.

Reactivity of Pt Complexes
Organometallics, Vol. 16, No. 26, 1997 5925

5926 Organometallics, Vol. 16, No. 26, 1997
Ara et al.

Reactivity of Pt Complexes
Organometallics, Vol. 16, No. 26, 1997 5927
Ta ble 3. Releva n t 13C NMR Sp ectr a l Da ta of
Sever a l Com p lexesa
(1)
Pt-CRt
tCâ-R
[Pt(CtCR)2(PPh2CtCR)2]
101.3 [1150] 109.3 (Ph) [313.9] 81 (101.6)
P-CRt
tCâ-R
1
2
3
4
107.9 (Ph)
84.7 [1145] 117 (But) [309]
81.8 (98.2) 107.2 (Ph)
102.3
108.8 (Ph) [∼310] 70.7 (105.5) 118.3 (But)
85.4 [1135] 116.4 (But) [307]
71.5 (101.7) 117.5 (But)
[{PPh2CtCR)2Pt(µ-η1:η2-CtCR)2}Pt(C6F5)2]
5
7
9
90.5
83.2
91
103.8 (Ph)
113.9 (But)
103.2 (Ph)
113.3 (But)
78.7 (112)
79.5 (109)
68.7 (115)
69.4 (112)
109.3 (Ph)
108.6 (Ph)
120.0 (But)
119.2 (But)
ligands: (i) the presence of strong absorptions (one for
1 and 2 or two for 3 and 4) in the 2167-2208 cm-1
region due to the ν(CtC) of the phosphinoalkyne ligands
shows that these groups are acting as P-donors. Com-
plexes 1, 3, and 4 display additional absorptions of
medium intensity in the 2117-2131 cm-1 region at-
tributed to the ν(CtC) of terminal alkynyl ligands. (ii)
11
84.1
[{cis-Pt(µ-κ(P):η2-PPh2CtCPh)2(µ-η1:η2CtCBut)2}{Pt(C6F5)2}2]
15A 87.7 78.3 (77.8) 109.5 (Ph)
124.6 (But)
[{PPh2CtCBut)2Pt(µ3-η2-CtCPh)2}{Pt(C6F5)2}2]
16B
67.5 (126.7) 121.4
[{cis-Pt(µ-κ(P):η2-PPh2CtCBut)2(µ-η1:η2CtCBut)2}{Pt(C6F5)2}2]
The presence of a singlet in the 31P{1H} NMR (δ -5.87,
18A 87.18
c (But)
70.5 (97.1) 113.2 (But)
1
195Pt-31
P
-7.90), especially the magnitude of J
(2311-
a
b
R ) PPh2CtCPh, PPh2CtCBut. Numbers in brackets are
2360 Hz) which is comparable to that reported for
mononuclear platinum complexes having a tertiary
phosphine trans to a terminal alkynide group, is con-
sistent with a cis configuration of the ligands about
platinum.6,7 In the 13C NMR spectra, the acetylenic
carbons (see Table 3 and Experimental Section for
details) are found in the typical chemical shift ranges
(CR/Câ, Pt-CRtCâ-R 84.7-102.3/108.8-117 ppm;
P-CRtCâ-R 70.7/118.3 ppm). The CR signals are
observed as a first-order doublet of doublets (Pt-CR) or
as a doublet (P-CR, dd for 1 and 2), while the alkyne
Câ resonances exhibit the typical A part of a second-
order AXX′ system. The two alkynyl (Pt-CRtCâR)
carbon signals could be easily identified due to their
significantly different coupling constants to the 195Pt
nuclei. The magnitude of the coupling constants 13C-
1J C-Pt or J C-Pt; numbers in parentheses are J C-P c A badly
.
3
1
resolved signal at 108.9 (m) can be tentatively assigned to this Câ
carbon.
(2)
2
195Pt (1J C-Pt ) 1135-1150 Hz, J C-Pt ) 309-314 Hz)
are comparable to those observed in similar neutral bis-
(alkynyl) complexes of the type [Pt(CtCR)2L2] (L )
phosphine)8 but, as expected, are notably larger than
those observed by us in the anionic derivatives
[Pt(CtCR)2X2]2- (X ) CtCR or C6F5) (924-1048)/250-
but in solution they decompose in a few hours. The
structural characterization of these dinuclear com-
pounds is based on microanalysis, positive ion FAB
mass spectrometry, and spectroscopic methods (IR
(Table 1) and 1H, 19F, and 31P NMR (Table 2)). In
agreement with a dimeric formulation, the FAB(+) mass
spectra show the expected peak corresponding to the
molecular ion in most of the complexes (Table 1).
The presence of terminal phosphinoalkyne ligands is
inferred from the IR spectra. Thus, all complexes show
ν(CtC) absorptions assignable to the phosphinoalkyne
ligands which lies approximately in the same region as
in the corresponding mononuclear derivatives. As in
the precursors, complexes 5-8 (L ) PPh2CtCPh) only
exhibit one strong ν(CtC) absorption (range 2179-2175
cm-1), while in the PPh2CtCBut complexes (9-12), two
absorptions in the range 2212-2168 cm-1 are seen. One
is assigned to ν(CtC), and the other one is assigned to
a Fermi resonance observed in substituted tert-butyl-
alkynes.10 Moreover, in concordance with the η2-
coordination of the alkynyl entities, some of the com-
pounds (6-8 and 12) also show additional weak (CtC)
1
293 Hz J C-Pt/2J C-Pt).9 Although all complexes (1-4)
exhibit signals due to the molecular peaks in the FAB-
(+) mass spectra, the most intense peaks correspond to
the loss of the two alkynyl groups [PtL2]+ (100), and the
peaks assignable to the loss of one alkynyl ligand [Pt-
(CtCR)L2]+ are also present.
Syn th eses of Din u clea r Com p lexes. In order to
develop the synthetic potential of these σ-bonded species
cis-[Pt(CtCR)2L2], we have studied their reactivity
toward cis-[M(C6F5)2(thf)2] (M ) Pt, Pd). As shown in
eq 2, treatment of cis-[Pt(CtCR)2L2] with 1 equiv of cis-
[M(C6F5)2(thf)2] (M ) Pt, Pd) in CH2Cl2 at room tem-
perature affords the homo- or heterobinuclear deriva-
tives [{L2Pt(µ-η1:η2-CtCR)2}M(C6F5)2] (5-12) in good
yield. These complexes, isolated as white microcrys-
talline solids, are moderately air-stable in the solid state
(7) (a) Cross, R. J .; Gemmill, J . J . Chem. Soc., Dalton Trans. 1984,
199. (b) Bradshaw, J . D.; Guo, L.; Tessier, C. A.; Youngs, W. J .
Organometallics 1996, 15, 2582. (c) Pregosin, P. S.; Kunz, R. W. In
NMR Basic Principles and Progress; Diehl, P., Fluck, E., Kosfeld, R.,
Eds.; Springer-Verlag: New York, 1979; Vol. 16, pp 43-45.
(8) (a) Sebald, A.; Wrackmeyer, B. Z. Naturforsch. 1983, 38b, 1156.
(b) Sebald, A.; Wrackmeyer, B.; Beck W. Z. Naturforsch. 1983, 38b,
45. (c) Sebald, A.; Stader, C.; Wrackmeyer, B.; Bensh, W. J . Organomet.
Chem. 1986, 311, 233.
(10) Grindley, T. B.; J ohnson, K. F.; Katritzky, A. R.; Keogh, H. J .;
Thirkettle, C.; Topsom, R. D. J . Chem. Soc., Perkin Trans. II 1974,
282.
(9) Berenguer, J . R.; Fornie´s, J .; Lalinde, E.; Mart´ınez, F. Organo-
metallics 1996, 15, 4537.

5928 Organometallics, Vol. 16, No. 26, 1997
Ara et al.
Sch em e 2
containing an η2-palladium(II)-alkyne moiety have
been reported.6c,9,12 These types of complexes have been
proposed as intermediates in the final formation of
unusual molecules arising from insertion and/or polym-
erization processes at the Pd(II) center.13 Due to the
peculiar ability of bis(alkynyl)platinum substrates to
stabilize unusual η2-metal-alkyne interactions, we have
previously isolated and reported the first two examples
[{cis-Pt(C6F5)2(µ-η1:η2-CtCSiMe3)2}Pd(η3-C3H5)]- 6c and
[{cis-(PPh3)2Pt(µ-η1:η2-CtCBut)2}Pd(η3-C3H5)]+ 9 con-
taining structural information about an η2-alkyne in-
teraction to a cationic palladium center “Pd(C3H5)+”.
Complex 10 represents a new example in which two
CtCPh ligands are η2-coordinated to an electrophilic
neutral palladium(II) center of the “Pd(C6F5)2” building
block.
The palladium center is located in a slightly distorted
square-planar environment formed by two η2-CtC
bonds (C(13)-C(14), C(21)-C(22)) and two σ-C6F5
ligands, the dihedral angle between the planes Pd-
C(1)-C(7) and Pd(1)-M1-M2 (M1 and M2 are the
midpoints of C(13)tC(14) and C(21)tC(22)) being only
6.6°. As found in the cation [{cis-(PPh3)2Pt(µ-η1:
η2-CtCBut)2}Pd(η3-C3H5)]+,9 the η2-palladium alkynido
linkages in 10 are asymmetric with the Pd-CR distances
approximately 0.15 Å shorter than the corresponding
Pd-Câ (Pd(1)-C(13), Pd(1)-C(21) 2.314(3), 2.283(3) Å
versus Pd(1)-C(14), Pd(1)-C(22) 2.456(4), 2.433(4) Å,
respectively). This asymmetry, although less pro-
nounced than that found in the cation [{cis-(PPh3)2Pt-
(µ-η1:η2-CtCBut)2}Pd(η3-C3H5)]+ 9 (∆ ∼ 0.2 Å), contrasts
with the symmetrical η2-linkages found in the anion
[{cis-Pt(C6F5)2(µ-η1:η2-CtCSiMe3)2}Pd(η3-C3H5)]- 6c and
in the neutral dinuclear complex [{(dppe)Pt(µ-η1:
η2-CtCR)2}Pt(C6F5)2],6a in which both alkynyl ligands
of the neutral 3-platinapenta-1,4-diyne neutral frag-
ment are also η2-coordinated to a similar M(C6F5)2
building block. The angles formed by the CtC vectors
and the normal to the palladium coordination plane (Pd,
C(1), C(7), M1, and M2) are 48.6(2)° for C(13,14) and
46.7(2)° for C(21,22). This structural feature clearly
forces the Pd center to be located out of the 3-platina-
1,4-diyne plane (Pt, C(13), C(14), C(21), C(22)) by 1.309-
(2) Å, resulting in a central bent dimetallacycle PtC4Pd
core (the dihedral angle formed by the Pd and Pt
coordination planes is 58.46(6)°). A similar structural
feature (type I, Scheme 2) has been found in other
F igu r e 1. View of the molecular structure of [{(ButCt
CPh2P)2Pt(µ-η1:η2-CtCPh)2}Pd(C6F5)2], 10.
Ta ble 4. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for 10
Pt(1)-C(21)
Pt(1)-P(1)
Pt(1)-Pd(1)
Pd(1)-C(7)
Pd(1)-C(13)
Pd(1)-C(14)
P(1)-C(47)
P(2)-C(41)
P(2)-C(35)
C(21)-C(22)
C(59)-C(60)
1.972(4)
2.2639(10)
3.1582(11)
2.003(3)
2.314(3)
2.456(4)
1.796(4)
1.735(4)
1.813(4)
1.210(5)
1.177(5)
Pt(1)-C(13)
Pt(1)-P(2)
Pd(1)-C(1)
Pd(1)-C(21)
Pd(1)-C(22)
P(1)-C(59)
P(1)-C(53)
P(2)-C(29)
C(13)-C(14)
C(41)-C(42)
1.983(4)
2.2783(11)
1.986(4)
2.283(3)
2.433(4)
1.729(4)
1.803(4)
1.801(4)
1.205(5)
1.189(5)
C(21)-Pt(1)-C(13)
C(13)-Pt(1)-P(2)
C(1)-Pd(1)-C(7)
81.87(14) C(21)-Pt(1)-P(1)
89.76(11) P(1)-Pt(1)-P(2)
83.87(14) C(1)-Pd(1)-C(21)
91.21(10)
97.16(4)
99.93(14)
C(7)-Pd(1)-C(13) 104.58(13) C(21)-Pd(1)-C(13) 68.59(13)
C(1)-Pd(1)-C(22) 80.77(13) C(7)-Pd(1)-C(14) 83.05(13)
C(14)-C(13)-Pd(1) 82.0(2)
C(14)-C(13)-Pt(1) 175.8(3)
C(13)-C(14)-C(15) 166.2(4)
C(22)-C(21)-Pd(1) 82.1(2)
C(21)-C(22)-C(23) 164.5(4)
C(41)-C(42)-C(43) 177.6(5)
C(59)-C(60)-C(61) 176.3(4)
C(22)-C(21)-Pt(1) 175.7(3)
Pt(1)-C(21)-Pd(1)
95.57(14)
C(42)-C(41)-P(2) 175.3(4)
C(60)-C(59)-P(1) 165.7(4)
absorptions at lower frequencies (range 2068-2040
cm-1), which is in keeping with the presence of bridging
alkynyl ligands. Unfortunately, this expected absorp-
tion assignable to the Pt(µ-CtCR)2M moiety is not
observed in the rest of the complexes. So, in order to
confirm the assignment made above, an X-ray diffrac-
tion study has been carried out on a single crystal of
one of the complexes, 10. A drawing of the structure is
presented in Figure 1, and selected bond distances (Å)
and angles (deg) are collected in Table 4. A relevant
feature of this structure is the presence of a palladium
atom coordinated to two mutually cis-σ C6F5 groups and
stabilized by a chelating bis(alkynyl)platinum(II) frag-
ment “cis-[Pt(CtCPh)2(PPh2CtCBut)2]” through un-
usual η2-alkynide interactions. In spite of the fact that
the reactivity of alkynes toward palladium(II) complexes
has been extensively explored,11 only a few complexes
(12) (a) [Pd2Cl4(ButCtCBut)2]: Hosokawa, T.; Moritani, I.; Nishioka,
S. Tetrahedron Lett. 1969, 3833. (b) cis-[Pd(C6F5)2(PhCtCPh)2]: Uso´n,
R.; Fornie´s, J .; Toma´s, M.; Menjo´n, B.; Welch, A. J . J . Organomet.
Chem. 1986, 304, C24. (c) Recently, several palladium(II) complexes
containing η1-metallacarbyne ligands (including X-ray and theoretical
studies) have been reported: (i) Engel, P. F.; Pfeffer, M.; Dedieu, A.
Organometallics 1995, 14, 3423. (ii) Engel, P. F.; Pfeffer, M.; Fisher,
J .; Dediu, A. J . Chem. Soc., Chem. Commun. 1991, 1275.
(13) (a) Ryabov, A. D.; van Eldik, R.; Le Borgne, G.; Pfeffer, M.
Organometallics 1993, 12, 1386 and references therein. (b) Backvall,
J .-E.; Nilson, Y. I. M.; Gatti, R. G. P. Organometallics 1995, 14, 4242
and references therein. (c) Zhn, G.; Lu, X. Organometallics 1995, 14,
4899.
(11) (a) Maitlis, P. M.; Espinet, P.; Rusell, M. J . H. In Comprehensive
Organometallic Chemistry; Wilkinson, G., Stone, F. G. A., Abel, E. W.,
Eds.; Pergamon Press: Oxford, U.K., 1982; Vol. 6, Chapters 38.5 and
38.9. (b) Maitlis, P. M. Acc. Chem. Res. 1976, 9, 93. (c) Maitlis, P. M.
J . Organomet. Chem. 1980, 200, 161. (d) Huggins, J . M.; Bergman, R.
G. J . Am. Chem. Soc. 1981, 103, 3002. (e) Samsel, E. G.; Norton, J . R.
J . Am. Chem. Soc. 1984, 106, 5505.

Reactivity of Pt Complexes
Organometallics, Vol. 16, No. 26, 1997 5929
dinuclear chelating [M](µ-CtCR)2M′Ln complexes con-
taining M′Ln building blocks with square-planar envi-
ronments at M′.6a-d However, this structural confor-
mation (type I, Scheme 2) contrasts with that typically
found in other well-known heterometallic tweezer-like
complexes in which the M′ center is well embedded by
bis(alkynyl)titanocene fragments displaying almost pla-
nar TiC4M′ cores (type II, Scheme 2).14 The factors
responsible for the preferred in or out-η2 alkyne-M
bonding interaction in this type of adduct are still poorly
understood. For instance, the only reported examples
in which a bis(alkynyl)platinum fragment forms tweezer-
like adducts correspond to [{(C6F5)2Pt(CtCSiMe3)2}-
oriented almost perpendicular to C(59)tC(60) (71.9(4)°),
but the linear alkynyl moieties do not cross one another.
The triple bonds are rotated away from one another,
and the separation between the two CR carbon atoms is
very large (3.355(5) Å). Carty et al. have established a
relationship between the facility of intramolecular
coupling of uncoordinated alkyne triple bonds in phos-
phinoalkynes and the proximity between the R-carbon
atoms of the proximal alkyne units.17b Thus, the
dichloro complex cis-[PtCl2(PPh2CtCPh)2] with the
linear alkynyl moieties “crossed” and with a CR-CR
separation of 3.110(10) Å undergoes alkyne coupling
under relatively mild conditions. However, our com-
pound with the triple bonds rotated shows no evidence
of coupling below its decomposition temperature.
15
MX2]2- (MX2 ) HgBr2 and CoCl216). In these anions,
the preference of the chelated metal center for in-plane
η2-alkyne-M bonding interactions could be ascribed to
their resulting tetrahedral environments with lower
steric requirements. However, in the related trinuclear
anion [{(Pt(CtCBut)2}(CoCl2)2]2-, the η2-alkyne cobalt
bonding interactions take place out of the Pt(CtC)2
entities16 and the bending of the central PtC4Co cores
is accompanied by a significant decrease in the Pt-Co
distance (0.44 Å). It was suggested that the weak
attraction between the basic platinum and acidic cobalt
centers (3.007 Å) appears to drive the distortion of the
PtC4Co core from planarity and, hence, determines the
final out-of-plane η2-alkyne-cobalt interactions. In
complex 10, the Pt‚‚‚Pd distance is also rather long
(3.1582(11) Å), excluding any metal-metal interaction.
As a consequence of the η2-coordination of the two
arms of the 3-platina-1,4-diyne fragment cis-[Pt(CtCPh)2-
(PPh2CtCBut)2] to the palladium atom Pd(1), the fol-
lowing structural features arise: (i) slight bending of
the Pt-CRtCâ-C units from linearity (angles at CR
175.8(3)°/175.7(3)° and at Câ 166.2(4)°/164.5(4)°) which
is comparable to those found in related systems6,9,14-16
and (ii) a slight decrease of the bite angle C(13)-Pt-
(1)-C(21) (81.87(14)°) with respect to the expected value
of 90°. It should be noted that this decrease (∼9°) is
slightly larger than those found in the tweezer-like
The 1H, 19F, and 31P NMR data for dinuclear com-
plexes 5-12 are consistent with the solid-state structure
of complex 10. Thus, 1H NMR spectra of tert-butyl-
acetylide-bridged complexes (7, 8, 11, and 12) show,
besides multiplets due to the phenyl protons, a singlet
at 0.78 (7, 8) or 0.76 (11, 12) ppm due to the equivalent
But groups, which remain as singlets even at -50 °C.
In addition, complexes 11 and 12 show another singlet
at 0.99 (11) or 1.00 (12) ppm attributed to the But groups
on the terminal PPh2CtCBut units, as in complexes 9
and 10 (δ 1.03 ppm). The equivalent phosphorus atoms
of the terminal phosphinoalkyne ligands in these di-
nuclear derivatives appear in the 31P NMR spectra at
systematically lower frequencies (range from δ -8.53
to -13.06) with respect to the values observed in the
precursors (δ -5.87 to -7.90). The magnitude of 1J Pt-P
(2644-2692 Hz) is slightly larger than in the corre-
sponding mononuclear homologues with terminal CtCR
groups (2311-2360 Hz), suggesting that the trans
influence of a bridging alkynyl ligand is presumably
smaller.
As is obvious from Figure 1, the two C6F5 groups in
these dinuclear derivatives (5-12) are equivalent but
the two halves of each C6F5 ring are inequivalent.
Accordingly, room temperature 19F NMR spectra of
complexes with tert-butylacetylide bridging ligands (7,
8, 11, and 12) display the expected five signals of equal
intensity, thus indicating a rigid structure on the NMR
time scale. In contrast, the NMR spectra of complexes
5, 6, 9, and 10 with phenylacetylide bridging ligands
show only three signals of relative intensity 2:1:2,
evidencing that the two halves of each C6F5 ring appear
equivalent at room temperature and indicating that
these complexes are not rigid in solution. By lowering
the temperature (-50 °C), five distinct fluorine reso-
nances are clearly resolved for the diplatinum deriva-
tives only (5, 9). When the heterobinuclear derivatives
[L2Pt(µ-CtCPh)Pd(C6F5)2] 6 (L ) PPh2CtCPh) and 10
(L ) PPh2CtCBut) are cooled, their spectra remain
unchanged indicating equivalence of the endo and exo
o-F atoms (and m-F atoms as well) even at low temper-
ature (-50 °C). This equivalence can be achieved by
either of the two following processes: (i) free rotation
of the C6F5 groups about the M-C linkages or (ii) fast
exchange of the M(C6F5)2 unit below and above the
3-platina-1,4-diyne fragments L2Pt(CtCPh)2. Although
the first possibility has been previously noted as se-
verely sterically hindered in square-planar derivatives,18
it has been proposed in several systems19 and could be
accessible via tricoordinate species through the cleavage
derivatives [{Pt(C6F5)2(CtCSiMe3)2}MX2] (MX2
)
HgBr2 88.0(9)°,15 CoCl2 86.5(9)° 16).
Apart from the above considerations, all other dis-
tances and angles in the organometallic platinum frag-
ment cis-[Pt(CtCPh)2(PPh2CtCBut)2] are within the
expected ranges17 (see Table 4). In particular, the CtC
bond lengths 1.189(5), 1.177(5) Å and angles 165.7(4)°,
177.6(5)° in the phosphinoalkyne ligands are those ex-
pected for noncoordinated phosphinoalkynes,17 although
the entity P(1)-C(59)-C(60) (165.7(4)°) is slightly more
deviated from linearity, probably due to steric effects.
The relative orientation of the two PPh2CtCPh
ligands is of interest. The C(41)tC(42) bond vector is
(14) (a) J anssen, M. D.; Ko¨hler, K.; Herres, M.; Dedieu, A.; Smeets,
W. J . J .; Spek, A. L.; Grove, D. M.; Lang, H.; van Koten, G. J . Am.
Chem. Soc. 1996, 118, 4817 and references therein. (b) J anssen, M.
D.; Herres, M.; Sepk, A. L.; Grove, D. M.; Lang, H.; Van Koten, G. J .
Chem. Soc., Chem. Commun. 1995, 925. (c) Lang, H.; Herres, M.;
Imohof, W. J . Organomet. Chem. 1994, 464, 283. (d) Lang, H.; Blau,
S.; Nuber, B.; Zsolnai, L. Organometallics 1995, 14, 3216 and references
therein. (e) Lang, H.; Ko¨hler, K.; Bu¨chner, M. Chem. Ber. 1995, 128,
525.
(15) Berenguer, J . R.; Fornie´s, J .; Lalinde, E.; Mart´ın, A.; Moreno,
M. T. J . Chem. Soc., Dalton Trans. 1994, 3343.
(16) Ara, I.; Berenguer, J . R.; Fornie´s, J .; Lalinde, E. Inorg. Chim.
Acta, in press.
(17) (a) Carty, A. J .; Taylor, N. J .; J ohnson, D. K. J . Am. Chem.
Soc. 1979, 101, 5422. (b) J ohnson, D. K.; Rukachaisirikul, T.; Sun, Y.;
Taylor, N. J .; Canty, A. J .; Carty, A. J . Inorg. Chem. 1993, 32, 5544.

5930 Organometallics, Vol. 16, No. 26, 1997
Ara et al.
of one of the M-alkyne bonds.20 The second possibility,
previously suggested by us in the related complexes
[L2Pt(µ-CtCR)2Pt(C6F5)2] (L ) PPh3, dppe, COD),6a
implies a formal inversion of the central PtC4M (M )
Pd, Pt) cores. This inversion could take place via inter-
mediate species with one or both alkynyl ligands sym-
metrically bridging the two metal centers.21 The results
indicate that this process is less favorable for the tert-
butylalkynide-bridged complexes than for phenyl com-
pounds because of the lower total energy required by
the phenyl complexes to reach the transition state which
is stabilized by the phenyl π electrons. Notwithstand-
ing, in these derivatives, exchange mechanisms that en-
tail PPh2CtCR participation cannot be excluded either.
The tert-butylacetylide complexes cis-[Pt(CtCBut)2L2]
(L ) PPh2
CtCPh (2), PPh2CtCBut (4)) react with 2.2
equiv of cis-[Pt(C6F5)2(thf)2] to give the desired tri-
nuclear derivatives 15A and 18A, respectively, in
moderate yield (see Experimental Section). In these
complexes (type A), the mononuclear precursors (2, 4)
act as symmetrical bis(cis-η2:κ(P):η2) chelating tetraden-
tate ligands. Therefore, the complexed cis-Pt(C6F5)2
units are linked to the central platinum atom through
both a tert-butylalkynyl fragment (µ-η2-CtCBut) and a
diphenylalkynylphosphine bridging ligand (µ-κ(P):η2), as
established by an X-ray diffraction study on complex
15A (vide infra). NMR (31P and 19F) monitoring of both
reactions clearly indicates that the formation of com-
plexes 15A and 18A takes place via the corresponding
dinuclear derivatives 7 and 11, respectively. Initially
(within seconds), the formation of 15A/7 and 18A/11
mixtures in ratios of 80:20 and ∼10:90, respectively,
were observed (see Scheme 3). The gradual disappear-
ance of 7 and concomitant formation of 15A is clean and
takes place completely in ∼1 h. However, the evolution
of the reaction system 4/cis-[Pt(C6F5)2(thf)2] is more
complicated due to the much slower formation of 18A
and to its low stability in solution; it reverts to the
dinuclear derivative. The greatest amount of 18A in
solution is reached after 3 h (18A/11 ratio ≈ 83:11), and
with longer reaction times, the concentration of 18A
decreases while that of 11 increases (a 55/45 ratio after
7 h). The formation of 15A and 18A through the
corresponding dinuclear derivatives requires a reorga-
nization of the bonded cis-Pt(C6F5)2 unit and a signifi-
cant reorientation of both phosphinoalkyne groups. It
seems likely that this latter process should be somewhat
more difficult with the bulkier PPh2CtCBut groups,
thus explaining the observed slower reaction rate for
complex 18A. Attempts to prepare the PtPd2 analogues
of 15A and 18A failed. When 2 equiv of cis-[Pd(C6F5)2-
(thf)2] is reacted with the mononuclear tert-butylal-
kynido derivatives 2 and 4 in dichloromethane, very
dark brown solutions are formed from which only the
dinuclear complexes 8 and 12, respectively, can be
isolated. In the case of the reaction between 4 and cis-
[Pd(C6F5)2(thf)2], the NMR spectra in CDCl3 of the
reaction mixture reveals that the dinuclear complex 12
is the only phosphorus-containing platinum species
present in solution. The 19F NMR spectrum confirms
the presence of excess cis-Pd(C6F5)2(thf)2 and shows the
formation of considerable amounts of decafluorobiphenyl
(C6F5-C6F5). If the C6F5-C6F5 formed comes from a
possible trinuclear coordination complex, it has a life-
time that is too short to allow observation by NMR
spectroscopy. NMR examination of the crude product
of the reaction mixture between 2 and cis-[Pd(C6F5)2-
(thf)2] reveals that, at low temperature (-50 °C), the
dinuclear complex 8 is formed almost instantaneously
and an excess of cis-[Pd(C6F5)2(thf)2] is the only other
solute present. When the temperature was increased
to room temperature, considerable decomposition takes
place (Pd, C6F5-C6F5) together with concomitant forma-
tion of other new unidentified platinum phosphine
complexes (31P NMR δ(P) 37.6 (d), 33.8 (m), 31.4 (d),
27.5 (d)). Unfortunately, the low relative amounts of
these species and the very low stability of the reac-
tion mixture at room temperature precluded their
identification.
The very low stability of the mixed Pt-Pd derivatives
(6, 8, 10, and 12) in solution prevented their charac-
terization by 13C NMR spectroscopy. This was, however,
possible for the diplatinum 5, 7, 9, and 11 compounds
(see Experimental Section and Table 3). The most
noticeable observation is that upon η2-coordination of
the alkynyl ligands to the platinum atoms, the reso-
nances of both CR and Câ carbon atoms moves slightly
upfield. A similar upfield shift of alkynyl carbon signals
has been previously observed in the formation of dimeric
[X2Pt(µ-CtCR)2Pd(C3H5)]- (X ) C6F5, CtCR)9 com-
plexes containing alkynyl bridging ligands. It should
be noted that this result contrasts with previous obser-
vations, showing that η2-complexation of terminal alky-
nyl ligands to a second metal center results in a
downfield shift of these signals.14d,22 On the other hand,
although the alkyne carbon resonances of the phosphi-
noalkyne ligands are less affected in the formation of
these dimeric complexes, the P-CRt carbon signals are
also slightly shifted upfield while the tCâ-R signals
1
move downfield. In addition, the values of the J P-C
R
coupling constants are slightly larger in these complexes
(109-115 Hz) than those observed in the precursors
1-4 (98.2-105.5 Hz) (see Table 3). It should be noted
that in complexes 7 and 11, the signals due to the
phenyl rings of the PPh2CtCR ligands are observed to
be magnetically inequivalent, probably because of the
hindered rotation across the Pt-P bonds.
Tr in u clea r Der iva tives. In order to force the
coordination of the P-bonded phosphinoalkyne ligands,
the reactions of the mononuclear complexes 1-4 with
2 equiv of cis-[M(C6F5)2(thf)2] (M ) Pt, Pd) were also
explored. The results, summarized in Scheme 3, clearly
indicate that the course of the reactions and the final
products strongly depend on the alkynyl substituents,
both in the alkynido and phosphinoalkyne ligands and
in the metal centers.
(18) (a) Albe´niz, A. C.; Cuevas, J . C.; Espinet, P.; de Mendoza, J .;
Prados, P. J . Organomet. Chem. 1991, 410, 257. (b) Abel, E. W.; Orrell,
K. G.; Osborne, A. G.; Pain, H. M.; Sik, W.; Hursthouse, M. B.; Malik,
K. M. A. J . Chem. Soc., Dalton Trans. 1994, 3441.
(19) (a) Berenguer, J . R.; Fornie´s, J .; Lalinde, E.; Mart´ınez, F.;
Urriolabeitia, E.; Welch, A. J . Chem. Soc., Dalton Trans. 1994, 1291.
(b) Ara, I.; Berenguer, J . R.; Fornie´s, J .; Lalinde, E.; Toma´s, M.
Organometallics 1996, 15, 1014. (c) Falvello, L. R.; Fornie´s, J .;
Navarro, R.; Rueda, A.; Urriolabeitia, E. P. Organometallics 1996, 15,
309.
(20) (a) Casares, J . A.; Coco, S.; Espinet, P.; Lin, Y.-S. Organome-
tallics 1995, 14, 3058. (b) Minniti, D. Inorg. Chem. 1994, 33, 2631.
(21) Berenguer, J . R.; Falvello, L.; Fornie´s, J .; Lalinde, E.; Toma´s,
M. Organometallics 1993, 12, 6.
(22) (a) Erker, G.; Fromberg, W.; Benn, R.; Mynott, R.; Angermund,
K.; Kru¨ger, C. Organometallics 1989, 8, 911. (b) Falvello, L. R.;
Ferna´ndez, S.; Fornie´s, J .; Lalinde, E.; Mart´ınez, F.; Moreno, M. T.
Organometallics 1997, 16, 1326.

Reactivity of Pt Complexes
Organometallics, Vol. 16, No. 26, 1997 5931
Sch em e 3
As shown in Scheme 3 (see Experimental Section),
similar reactions of 2 equiv of cis-[Pd(C6F5)2(thf)2] with
the cis-bis(phenylacetylide)bis((diphenylphosphino)-
alkyne) platinum complexes 1 and 3 in CH2Cl2 instan-
taneously yield a new type of triangular PtPd2 com-
plexes (14B and 17B) together with small amounts of
the corresponding dinuclear derivatives 6 (traces, less
than 5%) and 10 (∼20%), respectively, as proven by
NMR spectroscopy (31P and 19F). Crystallization of the
crude mixture at low temperature (CH2Cl2/hexane
interface) gave a pure sample of 17B. Both derivatives
are stable at low temperature (∼-30 °C) as solids but
rapidly decompose in CDCl3 at room temperature (∼12
h) to the corresponding dinuclear derivatives, depositing
Pd metal and giving, probably through a reductive
elimination process, a considerable amount of C6F5-
C6F5. An analogous reaction between complex 3 (L )
PPh2CtCBut) and 2 equiv of cis-[Pt(C6F5)2(thf)2] also
gives a similar mixture of 9 and the new triangular Pt3
complex 16B instantaneously, which is an isomer of
15A, in an approximate 15:85 mixture from which pure
16B can be isolated as a white microcrystalline solid in
high yield (45%) after work-up. The structure of
complex 16B, which is stable both as a solid and in
solution (CDCl3) has been determined by X-ray crystal-
lography, confirming that in this case the PPh2CtCBut
groups act as terminal ligands and both phenylethy-
nylalkyl fragments behave as six-electron donors (µ3-
η2, σ,π,π). Finally, the reaction between 1 (L )
PPh2CtCPh) and 2 equiv of cis-[Pt(C6F5)2(thf)2] is less
selective, giving both isomers 13A and 13B in a 50:32
ratio and ∼80% conversion (dinuclear complex 5, ∼18%,
is also present) after a reaction time of 2 h. Interest-
ingly, NMR (31P and 19F) examination of this reaction
shows (Scheme 3) an initial 13A:13B:5 mixture in a 50:
10:40 ratio. After 2 h, the signals assigned to complex
5 clearly have diminished while the proportion of 13B
has increased significantly. No detectible change was
observed after 8 h, with the final ratio being ∼50:32:18
as mentioned above. Several attempts to separate at
least the dominant component (13A) were unsuccessful;
therefore, both derivatives have been characterized
spectroscopically only on the basis of their NMR proper-
ties (mainly 31P), which are similar to these of the rest
of the complexes.
Both types of trinuclear complexes (A and B) display
very characteristic spectroscopic data consistent with
the corresponding formulation shown in Scheme 3 and
in agreement with the structures of 15A and 16B
presented in Figures 2 and 3, respectively. Thus, in the
IR spectra of complexes 15A and 18A, there are only
characteristic absorptions (see Table 1) in the expected
range for complexed carbon-carbon triple bonds,6,9,14,19a,22
thus confirming that all acetylene fragments are in-

5932 Organometallics, Vol. 16, No. 26, 1997
Ara et al.
Characteristic of the presence of (diphenylphosphino)-
alkyne bridging ligands in complexes of type A is a
considerable downfield shift of the 31P (δP) resonance
(δ(P) -0.92 (15A), -1.96 (18A), and 0.67 (13A)) with
respect to that observed in the mononuclear precursors
(-6.13 (2), -7.76 (4), -5.87 (1)) or in the corresponding
dinuclear derivatives in which the PPh2CtCR molecules
act only as P-donor ligands (-10.56 (7), -13.06 (11),
-10.4 (5)). This spectroscopic fact can be attributed to
the characteristic formation of (both) dimetallacycles in
which the PPh2CtCR ligands are involved as bridging
ligands. However, the platinum-phosphorus coupling
constants (2488 (15A), 2501 (18A), 2524 Hz (13A)) are
less affected, being slightly larger than those observed
for the starting precursors (2311 (2), 2335 (4), 2343 Hz
(1)) but slightly smaller than those seen for the di-
nuclear complexes (2674 (7), 2689 (11), 2679 Hz (5)).
In contrast, the equivalent phosphorus atoms of the
terminal phosphinoalkyne moieties in complexes of type
B appear in the 31P NMR spectra as singlets clearly
shifted to lower frequencies (δ(P) -19.5 (13B), -14.10
(14B), -20.55 (16B), -14.80 (17B)) with respect to the
values observed in the precursors (-5.87 (1), -7.90 (3))
and in the corresponding dinuclear derivatives (range
F igu r e 2. Drawing of the molecular structure of [{Pt(µ-
κ(P):η2-PPh2CtCPh)2(µ-η1:η2-CtCBut)2}{Pt(C6F5)2}2], 15A.
1
-8.53 (6) to -12.79 (9)). Moreover, all J Pt-P coupling
constants are extraordinarily large (range from 2891 Hz
for 14B to 3008 Hz for 16B) compared to the range
observed for either mononuclear and dinuclear com-
plexes (see Table 2). This points to a weaker σ-interac-
tion between Pt(1) and the CR carbon atoms of the
alkynyl ligands due to their additional interaction with
the remaining two platinum centers (σ-Pt(1), π-Pt(2),
π-Pt(3)) which seem to be compensated by stronger
interactions with the P-bonded phosphinoalkyne ligands.
Unfortunately, the 13C NMR spectrum of complex 16B
is not informative (see Experimental Section and Table
3) since the Pt-CRt carbon resonances could not be
located in spite of prolonged accumulation. The spectra
of 14B and 17B could not be obtained due to their very
low stability in solution.
The 19F NMR spectra of both types of complexes (A
and B) are temperature dependent (see Table 2). For
instance, at low temperature (-50 °C), complex 15A
displays two different sets of five fluorine signals (two
Fo, Fp, and two Fm), in keeping with the presence of two
inequivalent rigid C6F5 groups in which both halves of
each ring are inequivalent (AFMRX system). When the
temperature is increased, the two ortho and two meta
fluorine resonances of one of the sets clearly broaden
and, finally, collapse to only two broad signals at room
temperature (∼288 K) giving a ∆Gq (Tc) value of
approximately 53 KJ /mol for the process that renders
the o-F resonances equivalent.23 The remaining five
signals due to one of the C6F5 rings appear sharp at this
temperature (room temperature). The spectra can be
tentatively explained by assuming that the presence of
different ligands trans to the C6F5 rings (alkynyl and
phosphinoalkyne) induces different energy barriers on
their rotation around the Pt-Cipso(C6F5) bonds. Thus,
at low temperature the rotation seems to be stopped for
both rings, but at higher temperatures this process is
faster for one of them, averaging the two Fo (and the
two Fm) resonances. A similar behavior has been found
previously in other complexes containing the cis-Pt-
F igu r e 3. Molecular structure of [{(PPh2CtCBut)2Pt(µ3-
η2-CtCPh)2}{Pt(C6F5)2}2], 16B.
volved in side-on coordination. In contrast, the IR
spectra of complexes 14B, 17B (PtPd2), and 16B (PtPt2)
show two strong ν(CtC) absorptions in the range 2151-
2210 cm-1, indicating the presence of a terminal phos-
phinoalkyne ligand. All three complexes exhibit addi-
tional weak ν(CtC) bands at lower frequencies (1951
cm-1 (14B), 1883, 1870 (sh) (16B), and 1951 cm-1
(17B)), evidencing the presence of bridging alkynyl
ligands. It should be noted that in accord with the
behavior of alkynyl groups as six-electron donors, this
shift to lower frequencies (cf ν(CtC) at 2124 and 2117
cm-1 in 1 and 3, respectively) is significantly more
pronounced than that observed for the dinuclear com-
plexes in which ν(CtC) can be observed (range 2068-
2040 cm-1; 1951 cm-1 in 14B vs 2068 cm-1 in 6).
(23) Gu¨nther, H. NMR Spectroscopy; Wiley: New York, 1980; p 241.

Reactivity of Pt Complexes
Organometallics, Vol. 16, No. 26, 1997 5933
Ta ble 5. Selected Bon d Len gth s (Å) a n d An gles
different. The central Pt(2) atom is bound to the CR
atoms of the two CtCBut groups, which are mutually
cis, and to the two P atoms of the two PPh2CtCPh
ligands. The alkyne entities (CtCBut and PPh2CtCPh)
are each η2-coordinated to both terminal Pt(1) and Pt-
(3) atoms, which complete their coordination environ-
ment with the Cipso atoms of the two C6F5 groups, also
mutually cis. This structural disposition indicates that
again the reaction between complex 2 and 2 equiv of
cis-[Pt(C6F5)2(thf)2] proceeds with retention of the origi-
nal configuration about the platinum centers. It should
be noted, however, that the formation of complex 15A
through the dinuclear derivative 7 as an intermediate
(complex 15A is also formed starting from 7 and 1 equiv
of cis-[Pt(C6F5)2(thf)2]) requires at least a minor move-
ment of the initial cis-Pt(C6F5)2 unit bonded.
(d eg) for 15A‚0.5C6H12‚0.45C6H5
Pt(1)-C(19)
Pt(1)-C(38)
Pt(2)-C(25)
Pt(2)-P(1)
Pt(3)-C(57)
Pt(3)-C(26)
C(26)-C(27)
C(37)-C(38)
Pt(1)-C(13)
Pt(1)-C(32)
Pt(2)-C(31)
2.009(8)
2.257(8)
2.012(8)
2.282(2)
2.179(8)
2.322(8)
1.489(11)
1.233(11)
2.046(8)
2.299(8)
2.015(8)
Pt(3)-C(7)
Pt(3)-C(58)
P(1)-C(37)
C(27)-C(29)
Pt(1)-C(37)
Pt(1)-C(31)
Pt(2)-P(2)
Pt(3)-C(1)
Pt(3)-C(25)
C(25)-C(26)
C(31)-C(32)
2.020(8)
2.294(8)
1.769(8)
1.506(13)
2.219(7)
2.315(8)
2.271(2)
2.034(8)
2.307(8)
1.220(11)
1.211(11)
C(19)-Pt(1)-C(13)
C(13)-Pt(1)-C(38)
C(38)-Pt(1)-C(32)
C(37)-Pt(1)-C(31)
C(25)-Pt(2)-P(2)
C(31)-Pt(2)-P(1)
C(7)-Pt(3)-C(1)
C(1)-Pt(3)-C(58)
C(57)-Pt(3)-C(25)
C(57)-Pt(3)-C(26)
85.2(3) C(13)-Pt(1)-C(37)
93.6(3) C(19)-Pt(1)-C(32)
91.9(3) C(19)-Pt(1)-C(31)
77.9(3) C(25)-Pt(2)-C(31)
81.5(2) C(31)-Pt(2)-P(2)
89.3(2) P(2)-Pt(2)-P(1)
86.0(3) C(1)-Pt(3)-C(57)
80.6(3) C(7)-Pt(3)-C(25)
76.0(3) C(7)-Pt(3)-C(26)
93.2(3)
86.7(3)
99.1(3)
90.2(3)
169.2(2)
99.38(7)
100.9(3)
92.9(3)
92.5(3)
Both terminal platinum atoms Pt(1) and Pt(3) are
held in the complex by almost symmetrical π-bonding
interactions to the carbon-carbon triple bonds (the most
asymmetric interaction is found with the P-C(57)t
C(58)-Ph acetylenic fragment Pt(3)-C(57) 2.179(8) Å;
Pt(3)-C(58) 2.294(8) Å) with typical Pt(1,3)-CR,â dis-
tances (2.179(8)-2.322(8) Å).6 The C-C alkyne dis-
tances at the acetylenic carbons of the PPh2CtCPh
ligands (1.233(11), 1226(11) Å) are similar to the cor-
responding ones involving the CtCBut alkynyl groups
(1.220(1), 1.211(11) Å) but, as expected, longer than
those observed for complexes 10 (average 1.183(5) Å)
and 16B (average 1.184(13) Å) which have terminal
PPh2CtCBut ligands. These distances are within the
typical range of an alkyne bonded to transition metals
that do not strongly back-bond.4,6,15,16,19a The acetylenic
skeletons are slightly distorted from linearity, with the
bend at the CR carbon atoms more pronounced on the
P-CR-Câ-Ph entities (P-CR-Câ 154.6(7)°, 160.9(7)° vs
Pt-CR-Câ 166.5(7)°, 172.7(7)°). The angles at the Câ
carbon atoms are 162.1(8)° and 153.9(8)° on the Pt-
CR-Câ-C(But) entities and 160.5(8)°, 160.6(8)° at the
P-CR-Câ-C(Ph) fragments. The difference in the
values of the platinum coupling constants between the
dinuclear and trinuclear derivatives (A and B) is not
reflected in the platinum-phosphorus bond lengths,
which are identical within experimental error (mean
values 2.277(2) (15A), 2.271(10) (10), 2.276(2) Å (16B)).
As expected, the compound is not planar. The dihedral
angles between the best least-squares coordination
planes of each platinum center are Pt(1) plane-Pt(2)
plane ) 82.9°, Pt(2) plane-Pt(3) plane ) 80.35°, and
Pt(1) plane-Pt(3) plane ) 68.13°. The observed Pt(2)-
Pt(1,3) separations (3.560(1) and 3.597(1) Å) exclude the
possibility of metal-metal bonding.
85.5(3) C(26)-C(25)-Pt(2) 166.5(7)
C(25)-C(26)-C(27) 162.1(8) C(32)-C(31)-Pt(2) 172.7(7)
C(31)-C(32)-C(33) 153.9(8) C(38)-C(37)-P(1)
C(37)-C(38)-C(39) 160.5(8) C(58)-C(57)-P(2)
C(57)-C(58)-C(59) 160.6(8) Pt(1)-Pt(2)-Pt(3)
154.6(7)
160.9(7)
35.1(1)
(C6F5)2CO fragment, which also has different ligands
trans to the pentafluorophenyl groups.19a,b The behavior
of 18A is not clear (see Table 2 for data), as the two
sharp Fp triplets observed at room temperature, in
accord with the two expected types of C6F5 rings, also
broaden when the temperature is lowered. At -50 °C,
two sets of two overlapping triplets are seen, suggesting
that at low temperature the complex is rigid and all
C6F5 groups are inequivalent.
Similarly, in agreement with the behavior of the
phenylacetylide precursors 1 and 3 as chelating tet-
radentate bridging ligands binding through the alkynyl
groups to both cis-M(C6F5)2 units, the 19F NMR spectra
of 14B, 17B, and 16B at room temperature exhibit a
single set of three signals (2:1:2; 2Fo, Fp, 2Fm) evidencing
that all C6F5 groups are equivalent. The resonances
assignable to Fo and Fm are very broad, also suggesting
the existence of a dynamic process. On lowering the
temperature, splitting occurs and the expected pattern
corresponding to an AFMRX system is observed for all
complexes at -50 °C. Using the coalescence tempera-
tures given in Table 2 and the chemical shift difference
on Fo at 223 K, ∆Gq (Tc) values of 52.1 (14B), 47.6 (16B),
and 51.9 (17B) KJ /mol are obtained.23 The spectrum
of complex 17B remains unaffected in the presence of
an excess of cis-[Pd(C6F5)2(thf)2], suggesting an intramo-
lecular exchange process.
Cr ystal Str u ctu r es of [{P t(µ-K(P ):η2-P P h 2CtCP h )2-
(µ-η1:η2-CtCBu t )2}{P t (C6F 5)2}2]
(15A‚0.5C6H 14‚
A perspective drawing of the structure of complex 16B
is depicted in Figure 3 together with the atom-number-
ing scheme. A summary of the important bond dis-
tances and angles is given in Table 6. As shown, in this
complex the precursor fragment 3 acts a chelating
tetradentate ligand bound through the alkynyl groups,
giving a triangular Pt3 core with intermetallic angles
close to 60°. The Pt3 plane is bicapped by two triply
bridging phenylacetylide groups which are bonded in a
µ3-η2 (σ,2π) fashion. Thus, both alkynyl ligands remain
σ-bonded to Pt(1) (Pt(1)-C(1,9) 2.013(9), 2.001(9) Å) and
are π-bonded to Pt(2) and Pt(3) with platinum-carbon
distances in the range 2.266(9)-2.408(9) Å. It is
interesting to note that these distances and the CR
0.45C6H6) a n d [{(P P h 2CtCBu t)2P t(µ3-η2-CtCP h )2}-
{P t(C6F 5)2}2] (16B). The structure of the trinuclear
complex 15A is presented in Figure 2 together with the
atom-labeling scheme used. Selected bond distances
and angles are collected in Table 5. As shown, the most
remarkable feature is that both terminal cis-Pt(C6F5)2
moieties are linked to the central platinum atom
through both an alkynyl unit (µ-η2) and a phosphi-
noalkyne ligand (µ-κ(P):η2). To the best of our knowl-
edge, this is the first organometallic species possessing
such a structure.
The platinum atoms have basically square-planar
geometries, but their coordination environments are

5934 Organometallics, Vol. 16, No. 26, 1997
Ara et al.
η1-C2But)(µ-η2-C2But)(PPh2)2(CO)5(PPh2But)],25 [Cu3(µ3-
η1-CtCPh)2(µ-dppm)3](BF4),26 and [PtAg2(C6F5)2(µ-
η2,CtCR)(µ3-η1-CtCR)(PPh3)2],27 to our knowledge the
triangular Pt3 core bicapped by two (µ-η2-CtCPh)
ligands observed for 16B is unprecedented.
Ta ble 6. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for 16B
Pt(1)-C(9)
Pt(1)-P(2)
Pt(2)-C(59)
Pt(2)-C(1)
Pt(2)-Pt(3)
Pt(3)-C(9)
Pt(3)-C(2)
C(1)-C(2)
Pt(1)-C(1)
Pt(1)-Pt(3)
Pt(2)-C(53)
Pt(2)-C(9)
2.001(9)
2.281(2)
2.009(9)
2.330(8)
3.0982(5)
2.311(8)
2.375(9)
1.263(11)
2.013(9)
3.1973(5)
2.011(9)
2.337(8)
Pt(3)-C(71)
Pt(3)-C(10)
P(1)-C(17)
C(9)-C(10)
Pt(1)-P(1)
Pt(1)-Pt(2)
Pt(2)-C(2)
Pt(2)-C(10)
Pt(3)-C(65)
Pt(3)-C(1)
P(2)-C(35)
C(17)-C(18)
2.009(9)
2.337(9)
1.742(9)
1.270(12)
2.271(2)
3.2219(5)
2.266(9)
2.408(9)
2.028(9)
2.360(9)
1.733(10)
1.180(12)
Con clu sion
The coordination ability of cis-bis(alkynyl)bis((diphen-
ylphosphino)alkyne)platinum(II) complexes toward cis-
[M(C6F5)2(thf)2] (M ) Pt, Pd) has been studied. From
this study, it is clear that the alkynyl (CtCR) is the
preferred bridging ligand. Thus, exclusive formation of
double alkynyl bridging systems takes place in the
formation of all 1:1 adducts (5-12). In addition, com-
plexation via phenylethynyl fragments seems to pre-
dominate in the formation of trinuclear derivatives, as
deduced from the following results: (i) complexation of
the second cis-Pd(C6F5)2 unit is only straightforward
with the phenylethynyl substrates cis-[Pt(CtCPh)2L2]
(1 and 3) and takes place via CtCPh groups which act
as µ3-η2 bridging ligands; and (ii) while cis-[Pt(CtCPh)2-
(PPh2CtCBut)2] (3) binds both cis-Pt(C6F5)2 units
through a double alkynyl bridging system (µ3-η2-
CtCPh)2, 16B), cis-[Pt(CtCBut)2(PPh2CtCPh)2] (2)
forms the isomeric symmetrical adduct [{Pt(µ-κ(P):η2-
PPh2CtCPh)2(µ-η1:η2-CtCBut)2}{Pt(C6F5)2}2], 15A, con-
taining PPh2CtCPh bridging ligands. These results
establish the order of bonding capability as follows:
alkynyl > P-bonded phosphinoalkyne and CtCPh units
> CtCBut units. Finally, the formation of complexes
15A and 18A clearly shows that the preference for η2-
alkyne-metal interactions is higher in platinum than
in palladium substrates.
C(9)-Pt(1)-C(1)
C(9)-Pt(1)-P(2)
Pt(3)-Pt(1)-Pt(2)
C(53)-Pt(2)-C(2)
C(59)-Pt(2)-C(9)
C(59)-Pt(2)-C(10)
Pt(3)-Pt(2)-Pt(1)
C(65)-Pt(3)-C(9)
C(65)-Pt(3)-C(10)
C(71)-Pt(3)-C(1)
C(9)-Pt(3)-C(1)
C(10)-Pt(3)-C(2)
C(2)-C(1)-Pt(1)
C(1)-C(2)-Pt(2)
Pt(2)-C(2)-Pt(3)
C(10)-C(9)-Pt(3)
C(9)-C(10)-Pt(3)
Pt(3)-C(10)-Pt(2)
76.2(3)
91.2(2)
C(1)-Pt(1)-P(1)
P(1)-Pt(1)-P(2)
96.3(3)
96.36(9)
88.9(4)
100.6(3)
64.1(3)
97.8(3)
87.4(4)
57.715(12) C(59)-Pt(2)-C(53)
87.4(3)
101.7(3)
84.7(3)
C(53)-Pt(2)-C(1)
C(1)-Pt(2)-C(9)
C(2)-Pt(2)-C(10)
60.744(12) C(71)-Pt(3)-C(65)
104.0(3)
91.3(3)
100.2(3)
64.0(3)
96.7(3)
163.4(8)
76.9(6)
83.7(3)
75.3(5)
73.0(6)
81.5(3)
C(71)-Pt(3)-C(10) 164.0(4)
C(9)-Pt(3)-C(10)
C(65)-Pt(3)-C(1)
C(71)-Pt(3)-C(2)
Pt(2)-Pt(3)-Pt(1)
C(1)-C(2)-C(3)
C(1)-C(2)-Pt(3)
C(10)-C(9)-Pt(1)
C(9)-C(10)-C(11)
C(9)-C(10)-Pt(2)
C(18)-C(17)-P(1)
31.7(3)
154.6(3)
83.7(3)
61.541(11)
152.5(9)
73.9(6)
168.9(7)
150.9(9)
71.4(5)
170.2(9)
C(17)-C(18)-C(19) 178.6(10)
C(35)-C(36)-C(37) 176.6(11)
C(36)-C(35)-P(2) 175.6(10)
(168.9(7)°, 163.4(8)°) and Câ (150.9(9)°, 152.5(9)°) bend-
ing of the alkynyl ligands are comparable to the
parameters found in [(dppe)Pt(µ-η2-CtCPh)2Pt(C6F5)2]
(Pt(2)-C 2.269(13)-2.345(12) Å; angles at CR 167.2°/
159.2° and at Câ 164.6°/156.2°) in which the 3-platina-
1,4-alkyne fragment chelates only one Pt(C6F5)2 frag-
ment.6a However, the carbon-carbon triple bond dis-
tances are, as expected, slightly longer (1.270(12), 1.263-
(11) Å in 16B vs 1.229(17), 1.234(16) Å in the dinuclear
derivative),6a and the bite angle C(1)-Pt(1)-C(9) of
76.2(3)° is only slightly smaller than that found in
[(dppe)Pt(µ-η2-CtCPh)Pt(C6F5)2] (79.3(4)°).
The platinum-platinum distances (Pt(1)-Pt(2,3)
3.2219(5), 3.1973(5) Å and Pt(2)-Pt(3) 3.0982(5) Å) are
consistent with nonbonding interactions. As expected,
the geometry around the platinum atoms is approxi-
mately square planar. An interesting structural feature
is that, probably due to the presence of two Pt(C6F5)2
units above and below the Pt(1) coordination plane, the
chelating platinadiyne fragment [Pt(1)C(1)C(9)C(2)C-
(10)] is nearly planar (max deviation 0.020 Å for C(9))
with the phenyl substituents of the alkynyl ligands also
lying in the same plane. The dihedral angles between
these phenyl groups and the above platinadiyne plane
are 38.0° and 36.5°, respectively.
Exp er im en ta l Section
Gen er a l Meth od s. All reactions were carried out under
N2 using dried solvents purified by known procedures and
distilled prior to use. IR spectra were recorded on a Perkin-
Elmer 883 spectrometer from Nujol mulls between polyethyl-
ene sheets. NMR spectra were recorded on a Varian Unity
300 and a Bruker ARX 300 spectrometer. Chemical shifts are
reported in ppm relative to external standards (SiMe4, CFCl3,
and 85% H3PO4). Elemental analyses were carried out with
a Perkin-Elmer 240-B microanalyzer and the mass spectra
(FAB+) on a VG Autospec spectrometer. [PPh2CtCPh],28
[PPh2CtCBut],28 [Pt(CtCPh)2COD],29 [Pt(CtCBut)2COD],6a
and cis-[Pt(C6F5)2(thf)2]30 were prepared by published proce-
dures.
Syn th esis of cis-[P t(CtCR)2L2] (L ) L1 ) P P h 2CtCP h ,
R ) P h (1), Bu t (2); L ) L2 ) P P h 2CtCBu t, R ) P h (3),
Bu t (4)). A typical preparation (complex 1) was as follows:
To a suspension of [Pt(CtCPh)
2COD] (0.200 g, 0.396 mmol)
in CH2Cl2 (10 cm3) was added PPh2CtCPh (0.226 g, 0.791
mmol), immediately giving an orange solution. After the
mixture was stirred for 10 min, the resulting solution was
The reasons for the final formation of these triangular
molecules only with the phenylacetylide 1 and 3 precur-
sors are difficult to discern, but the steric effects of the
bulky tert-butylacetylide ligands cannot be discarded.
Although several systems with two bridging alkynyl
ligands have been reported so far [Os3(CO)7(µ-η2CtCPri)2-
(µ-PPh2)2],24a [Os3(µ-η1-C2R)(µ3,η2-C2R)(CO)9],24b,c [Ru3(µ-
(25) Carty, A. J .; Taylor, N. J .; Smith, W. F. J . Chem. Soc., Chem.
Commun. 1979, 750.
(26) (a) D´ıez, J .; Gamasa, M. P.; Gimeno, J .; Aguirre, A.; Garc´ıa-
Granda, S. Organometallics 1991, 10, 380. (b) D´ıez, J .; Gamasa, M.
P.; Gimeno, J .; Lastra, E.; Aguirre, A.; Garc´ıa-Granda, S. Organome-
tallics 1993, 12, 2213.
(27) Ara, I.; Fornie´s, J .; Lalinde, E.; Moreno, M. T.; Toma´s, M. J .
Chem. Soc., Dalton Trans. 1994, 2735; 1995, 2397.
(28) Carty, A. J .; Hota, N. K.; Ng, T. W.; Patel, H. A.; O’Connor, T.
J . Can. J . Chem. 1971, 49, 2706.
(29) Cross, R. J .; Davidson, M. F. J . Chem. Soc., Dalton Trans. 1986,
1987.
(24) (a) Cherkas, A. A.; Taylor, N. J .; Carty, A. J . J . Chem. Soc.,
Chem. Commun. 1990, 385. (b) Deeming, A. J .; Felix, M. S. B.; Bartes,
P. A.; Hursthouse, M. B. J . Chem. Soc., Chem. Commun. 1987, 461.
(c) Deeming, A. J .; Felix, M. S. B.; Nuel, D. Inorg. Chim. Acta 1993,
213, 3.
(30) Uso´n, R.; Fornie´s, J .; Toma´s, M.; Menjo´n, B. Organometallics
1985, 4, 1912.

Reactivity of Pt Complexes
Organometallics, Vol. 16, No. 26, 1997 5935
evaporated to dryness. Then, the addition of cold diethyl ether
(5 cm3) gave 1 as a white solid.
[{(P h CtCP h 2P )2P t(µ-η1:η2-CtCBu t)2}P t(C6F 5)2] (7) 13C
NMR (CDCl3, 16 °C): 148.1 (m), 145.1 (m), 137.8 (m), 134.6
(m) (br, C6F5), 133.0 (m, overlapping of two triplets, Co, PPh2),
131.8 (s, Co, Ph), 131.2 (AXX′, 1J CP + 3J CP ) 45.7 Hz, Ci, PPh2),
∼130.3 (Ci, PPh2), 130.8 (s, Cp, PPh2), 130.6 (s, Cp, PPh2), 129.8
(s, Cp, Ph), 128.1 (m, overlapping of two triplets, Cm, PPh2),
127.8 (s, Cm, Ph), 120.1 (s, Ci, Ph), 113.9 (m, Câ, CRtCâBut, Pt
satellites are not observed), 108.6 (m, Câ, P-CRtCâPh), ∼83.2
(CR, -CRtCâBut), 79.5 (d, J CP ) 109 Hz, CR, -PCRtCâPh), 30.7
(s, -C(CH3)3), 30.1 (s, CMe3).
Complexes 2, 3, and 4 were prepared similarly as white
solids by using the appropriate starting materials. For
complexes 3 and 4, the resulting reaction mixtures were
i
evaporated to dryness and the residue was treated with PrOH
giving the required products.
cis-[P t(CtCP h )2(P P h 2CtCP h )2] (1) 13C NMR (CDCl3,
16 °C): 133.4 (t, J CP ) 6.3 Hz, Co, PPh2), 131.8 (s, Co,
P-CtCPh), 131.3 (s, 4J Pt-C ) 8.8 Hz, Co, CtCPh), 130.6 (AXX′
[{(Bu tCtCP h 2P )2P t(µ-η1:η2-CtCP h )2}P t(C6F 5)2] (9) 13C
NMR (CDCl3, 16 °C): 147.8 (m), 144.9 (m), 137.6 (m), 134.4
(m, br, C6F5), 132.9 (t, J CP ) 6.6 Hz, Co, PPh2), 131.9 (s, Ph),
1
3
five line pattern, J CP + J CP ) 66.4 Hz, Ci, PPh2), 130.2 (s,
Cp, PPh2), 129.5 (s, Cp, Ph), 127.9 (t, J CP ) 5.9 Hz, Cm, PPh2),
127.8 (s, Cm, Ph), 126.8 (s, Cm, Ph), 124.9 (s, Ph), 120.6 (s,
1
3
3
+ 3J CP ) 36.5 Hz,
131.6 (AXX′ five line pattern, J CP + J CP ) 69 Hz, Ci, PPh2),
130.8 (s, Cp, PPh2), 128.2 (t, J CP ) 6 Hz, Cm, PPh2), 127.7 (s,
Ph), 109.3 (AXX′ five line pattern, J CP
trans
cis
2J Pt-C ) 313.8 Hz, Câ, -CRtCâPh), 107.9 (AXX′, J CP
+
2
â
4J CP ) 15.1 Hz, Câ, P-CRtCâPh), 101.3 (dd, J CP
) 156.5
2
Cp, Ph), 126.9 (s, Cm, Ph), 124.3 (s, Ci, Ph), 120.0 (m, Câ,
trans
3
-PCRtCâBut), 103.2 (m, J C-P
+
3J C-P ) 30.6 Hz, Câ,
2
1
Hz, J CP ) 21.2 Hz, J Pt-C ) 1150 Hz, CR, -CRtCâPh), 81.0
(dd, J CPcis ) 101.6 Hz, J CP ) 1.2 Hz, J Pt-C ≈ 17 Hz, CR,
trans
cis
R
-CRtCâPh), 91.3 (dm, 2J C-Ptrans ≈ 145 Hz, CR, -CRtCâPh), 68.7
1
3
2
(d, J CP ) 115 Hz, CR, -PCRtCâBut), 29.5 (s, -C(CH3)3), 28.3
1
P-CRtCâPh).
cis-[P t(CtCBu t)2(P P h 2CtCP h )2] (2) 13C NMR (CDCl3,
(s, CMe3).
[{(Bu tCtCP h 2P )2P t(µ-η1:η2-CtCBu t)2}P t(C6F5)2] (11) 13C
NMR (CDCl3, 16 °C): 133.1 (Co), 133.02 (Co) (overlapping of
two triplets PPh2), 132.20 (Ci), 132.17 (Ci) (overlapping of two
AXX′ fine line patterns), 130.5 (s, Cp, PPh2), 127.97 (Cm), 127.85
(Cm) (overlapping of two triplets PPh2), 119.2 (t, J CP ) 7.6 Hz,
Câ, PCRtCâBut), 113.3 (AXX′, 3J C-Ptrans + 3J C-Pcis ) 29.4 Hz, Pt
3
16 °C): 133.6 (t, J CP ) 6.2 Hz, J Pt-C ) 28.8, Co, PPh2), 131.7
1
3
(s, Cp, PPh2), 131.4 (AXX′ five line pattern, J CP + J CP ) 65
Hz, Ci, PPh2), 129.8 (s, Co, Ph), 129.2 (s, Cp, Ph), 127.7 (s, Cm,
Ph), 120.9 (m, Ci, Ph), 117.0 (AXX′ five line pattern, 3J CP
+
trans
3J CP ) 35.9 Hz, J Pt-C ) 309 Hz, Câ, -CRtCâBut), 107.2 (m,
2
cis
Câ, P-CRtCâPh), 84.7 (dd, 2J CPtrans ) 158 Hz, 2J CPcis ) 21.4 Hz,
satellites are not observed, Câ, -CRtCâBut), 84.1 (dd, 2J C-P
1J Pt-C ) 1145 Hz, CR, -CRtCâBut), 81.8 (dd, J CP ) 98.2 Hz,
1
trans
R
) 145.9 Hz, J C-P ) 20.5 Hz, CR, CRtCâBut), 69.4 (d, J CP
)
2
3J CP ) 1.4 Hz, 2J Pt-C ) 14 Hz, CR, P-CRtCâPh), 31.45 (s, 4J Pt-C
cis
112 Hz, CR, -PCRtCâBut), 30.7 (s, -CH3), 30.08 (s, CMe3), 29.5
(s, -CH3), 29.2 (s, CMe3).
3
) 7.9 Hz, -C(CH3)3), 28.6 (s, J Pt-C ) 21.4 Hz, -CMe3).
cis-[P t(CtCP h )2(P P h 2CtCBu t)2] (3) 13C NMR (CDCl3,
16 °C): 133.4 (t, J CP ) 6.2 Hz, Ph, Co, PPh2), 131.97 (AXX′
five line pattern, 1J CP + 3J CP ) 66 Hz, Ci, PPh2), 131.3 (s, Ph),
130.0 (s, Cp, PPh2), 127.7 (t, J CP ) 6 Hz, Cm, PPh2), 126.8 (s,
Ph), 124.7 (s, Ph), 118.3 (t, J CP ) 7 Hz, Câ, -PCRtCâBut), 108.8
Rea ction of cis-[P t(CtCP h )2L12] (1) w ith cis-[P t(C6F 5)2-
(th f)2] (Mola r Ra tio of 1:2). A mixture of cis-[Pt(C6F5)2(thf)2]
(0.015 g, 0.022 mmol) and cis-[Pt(CtCPh)2(PPh2CtCPh)2]
(0.0108 g, 0.011 mmol) was dissolved in 0.6 cm3 of CDCl3, and
the reaction was immediately monitored by NMR spectroscopy.
Integration of the NMR signals shows an approximate 50:10:
40 proportion of 13A, 13B, and 5 (Scheme 3). After 2 h, the
intensity of the signal due to the dinuclear derivative 5
decreases while the signal attributed to 13 increases with the
final proportion being 13A:13B:5 50:32:18. An identical ratio
was observed after 8 h.
(AXX′, 3J C-Ptrans + 3J C-P ) 36 Hz, 2J Pt-C ≈ 310 Hz, Câ, -CRtCâ-
cis
Ph), 102.3 (dd, 2J C-Ptrans ) 136 Hz, 2J C-Pcis ) 21 Hz, Pt satellites
are not observed, CR, -CRtCâPh), 70.7 (d, J CP ) 105.5 Hz, CR,
P-CRtCâBut), 29.6 (s, -C(CH3)3), 28.1 (s, -C(Me3)).
cis-[P t(CtCBu t)2(P P h 2CtCBu t)2] (4) 13C NMR (CDCl3,
3
16 °C): 133.6 (t, J CP ) 6.2 Hz, J Pt-C ) 28.4, Co, PPh2), 132.8
1
3
(five line pattern AXX′, J CP + J CP ) 65 Hz, Ci, PPh2), 129.5
All attempts to separate 13A or 13B from this reaction
mixture were unsuccessful; thus, the complexes 13A and 13B
were only characterized by spectroscopy: 1H NMR (CDCl3,
ppm) δ 8.00-6.8 (m, 13A + 13B); 19F NMR (CDCl3, ppm)
-116.5 (br), -117.2 (s, br) (Fo, 13A + 13B), -160.97 (t), -161.1
(t), -161.5 (t) (3Fp: 2 inequivalent Fp from 13A and 1 Fp from
13B), -164.1 (m), -164.6 (m) (Fm, 13A + 13B); 31P{1H} NMR
(s, Cp, PPh2), 127.3 (t, J CP ) 5.8 Hz, Cm, PPh2), 117.5 (t, J CP
)
)
6.5 Hz, Câ, -PCRtCâBut), 116.4 (AXX′, J C-P
+
3J C-P
3
trans
cis
35.7 Hz, J Pt-C ) 307 Hz, Câ, -CRtCâBut), 85.4 (dd, J C-P
2
2
â
trans
) 158.7 Hz, 2J C-P ) 21.2 Hz, 1J Pt-C ) 1135 Hz, CR, -CRtCâ-
But), 71.45 (d, 1J CP ) 101.7 Hz, 2J Pt-CR) 17.9 Hz, CR, -PCRtCâ-
cis
But), 31.4 (s, -C(CH3)3, CRtCâBut), 29.6 (s, -C(CH3)3, -PCRtCâ-
But), 28.5 (s, J Pt-C ) 21.7 Hz, -C(Me3), CRtCâBut), 28.0 (s,
3
1
1
-C(Me3), -PCRtCâBut).
(CDCl3, ppm) 0.67 (s, J Pt-P ) 2524 Hz, 13A), -19.5 (s, J Pt-P
1
Syn th esis of [{L2P t(µ-η1:η2-CtCR)2}M(C6F 5)2] (L ) L1
) P P h 2CtCP h , R ) P h , M ) P t (5), P d (6); R ) Bu t, M )
P t (7), P d (8); L ) L2 ) P P h 2CtCBu t; R ) P h , M ) P t (9),
P d (10); R ) Bu t, M ) P t (11), P d (12)). Syn th esis of 5.
To a solution of cis-[Pt(CtCPh)2(PPh2CtCPh)2] (0.140 g, 0.144
mmol) in CH2Cl2 (20 cm3) was added cis-[Pt(C6F5)2(thf)2] (0.097
g, 0.144 mmol), and the mixture was stirred at room temper-
ature for 15 min. The resulting solution was concentrated to
small volume (2 cm3). Addition of n-hexane (3 cm3) and
standing at -30 °C gave 5 as a white crystalline product.
Complexes 6-12 were prepared similarly using the appropri-
ate starting materials.
) 2996 Hz, 13B). The signal due to complex 5 (-10.8, J Pt-P
) 2677 Hz) is also present.
Syn th esis of [{L12P t(µ3-η2CtCP h )2}{P d (C6F 5)2}2], 14B.
cis-[Pd(C6F5)2(thf)2] (0.100 g, 0.171 mmol) was added to a
stirred solution of cis-[Pt(CtCPh)2(PPh2CtCPh)2] (1; 0.083 g,
0.086 mmol) in CH2Cl2 (5 cm3). The resulting solution was
immediately evaporated to dryness, and the residue was
treated with n-hexane (5 cm3) to give a white powder (70%
yield). The 31P NMR spectrum of this solid shows it to be
complex 14B with a purity >95%. Only traces (less 5%) of
complex 6 were also observed. On standing at room temper-
ature (∼12 h), considerable decomposition to Pd metal takes
place and the only species detected thereafter by 31P{1H} and
19F spectroscopy were the dinuclear complex 6 and decafluo-
robiphenyl (C6F5-C6F5). Identical results were obtained start-
ing from 6 and 1 equiv of cis-[Pd(C6F5)2(thf)2].
[{(P h CtCP h 2P )2P t(µ-η1:η2-CtCP h )2}P t(C6F 5)2] (5) 13C
NMR (CDCl3, 16 °C): 147.8, 144.8, 137.7, 134.5 (br, C6F5),
132.9 (t, J CP ) 6.6 Hz, Co, PPh2), 131.96 (s, Ph), 131.9 (s, Ph),
1
130.98 (s, Ph), 130.2 (AXX′ five line pattern, J CP + 3J CP ) 69
Hz, Ci, PPh2), 130.1 (s, Cp, Ph), 128.4 (t, J CP ) 6.1 Hz, Cm,
PPh2), 127.9 (s, Cm, Ph), 127.8 (s, Cp, Ph), 126.9 (s, Cm, Ph),
Syn t h esis of [{P t (µ-K(P ):η2-P P h 2CtCP h )2(µ-η1:η2-
CtCBu t)2}{P t(C6F 5)2}2], 15A. cis-[Pt(C6F5)2(thf)2] (0.152 g,
0.229 mmol) was added to a solution of [Pt(CtCBut)2-
(PPh2CtCPh)2] (2; 0.100 g, 0.107 mmol) in CH2Cl2 (10 cm3),
and the mixture was stirred for 1 h at room temperature. The
resulting yellow solution was evaporated to dryness, and the
residue was treated with a mixture of diethyl ether/hexane
2
4
124.2 (s, Ci, Ph), 119.8 (s, Ci, Ph), 109.3 (AXX′, J CP + J CP
)
3
17.3 Hz, Câ, P-CtCPh), 103.8 (AXX′, five line pattern J C-P
trans
+ 3J C-P ) 30.5 Hz, Câ, -CRtCâPh), 90.5 (dd, 2J C-Ptrans ) 145.5
cis
Hz, 2J C-P ) 19.8 Hz, CR, -CRtCâPh), 78.7 (d, 1J CP ) 112 Hz,
cis
CR, -PCRtCâPh).

5936 Organometallics, Vol. 16, No. 26, 1997
Ara et al.
Ta ble 7. Cr ysta l Da ta a n d Str u ctu r e Refin em en t P a r a m eter s for Com p lexes 10‚Me2CO,
15A‚0.5C6H14‚0.45C6H6, a n d 16Ba
complex
10‚Me2CO
15A‚0.5C6H14‚0.45C6H6
16B
empirical formula
fw
C64H48F10P2PdPt‚Me2CO
1428.53
C76H48F20P2Pt3‚0.5C6H12‚0.45C6H6
2065.65
C76H48F20P2Pt3
1988.35
unit cell dimens
a (Å)
b (Å)
9.863(4)
15.314(5)
19.840(6)
88.46(2)
86.71(1)
82.54(2)
2966(2), 2
0.710 73
14.0631(10)
17.6645(12)
17.9951(15)
76.082(12)
72.341(10)
86.577(10)
4134.2(6), 2
0.710 73
150
graphite-monochromated Mo KR
triclinic
14.8963(12)
23.5869(11)
19.8044(11)
90
100.596(8)
90
6839.8(7), 4
0.710 73
150
c (Å)
R (deg)
â (deg)
γ (deg)
volume (Å3), Z
wavelength (Å)
temperature (K)
radiation
200
graphite-monochromated Mo KR
triclinic
graphite-monochromated Mo KR
monoclinic
cryst syst
space group
cryst dimens (mm)
P1h
P1h
P21/c
0.74 × 0.46 × 0.32
0.30 × 0.20 × 0.20
0.50 × 0.25 × 0.25
abs coeff (mm-1
)
2.787
5.197
6.267
transmission factors
abs corr
diffractometer
2θ range for data
collection (deg)
0.991, 0.630
ψ scans
Siemens STOE/AED2
2.1-24.0 (+h, (k, (l)
0.438, 0.350
ψ scans
Enraf-Nonius CAD4
2.0-25.0 (+h, (k, (l)
0.984, 0.625
ψ scans
Enraf-Nonius CAD4
2.0-25.0 (+h, +k, (l)
no. of reflns collected
no. of indep reflns
refinement method
goodness-of-fit on F2
final R indices (I > 2σ(I))
R indices (all data)
11 110
15 107
12 463
9268 (R(int) ) 0.0238)
full-matrix least-squares on F2
1.043
R1 ) 0.0239, wR2 ) 0.0539
R1 ) 0.0306, wR2 ) 0.0586
14 465 (R(int) ) 0.0298)
full-matrix least-squares on F2
1.002
R1 ) 0.0415, wR2 ) 0.1077
R1 ) 0.0633, wR2 ) 0.1178
11 971 (R(int) ) 0.0366)
full-matrix least-squares on F2
1.048
R1 ) 0.0432, wR2 ) 0.0652
R1 ) 0.0945, wR2 ) 0.0789
a
2
2
2
R1 ) ∑(|Fo| - |Fc|)/∑|Fo|; wR2 ) [∑w(Fo - Fc )2/∑w(Fc2)2 ]1/2. Goodness-of-fit ) [∑w(Fo - Fc2)2/(nobs - nparam)]1/2. w ) [σ2(Fo) + (g1P)2
+ g2P]-1; P ) [max(Fo2; 0) + 2Fc2]/3.
(3/2). Cooling at -30 °C for 12 h gives complex 15A as a pale
yellow microcrystalline solid (0.18 g).
Syn th esis of [{L22P t(µ3-η2CtCP h )2}{P d (C6F 5)2}2], 17B.
cis-[Pt(CtCPh)2(PPh2CtCBut)2] (3; 0.0608 g, 0.0654 mmol)
and 0.0764 g (0.1307 mmol) of cis-[Pd(C6F5)2(thf)2] were mixed
in CH2Cl2 (5 cm3), and the resulting solution was immediately
evaporated to dryness. The residue was extracted with hexane
(2 × 5 cm3), giving a beige solid (17B:10 ≈ 90:10 by 31P NMR).
Recrystallization of this solid (CH2Cl2/hexane interface at -30
°C) yielded 17B as a colorless powder.
13C NMR (CDCl3, -50 °C): ∼146, 144, 138.1, 135.3 (br,
C6F5), 134.5-128.5 (Ph), 124.6 (m, Câ, -CRtCâBut), 119.4 (s,
Ph), 109.5 (m, Câ, -PCRtCâPh), 87.7 (dd, 2J C-Ptrans ) 151.8 Hz,
1
2J C-P ) 15.5 Hz, CR, -CRtCâBut), 78.3 (d, J CP ) 77.76 Hz,
cis
CR, P-CRtCâPh), 30.7 (s, -C(CH3)3), 31.7, 22.7, 14.4 (s,
hexane).
When the reaction was monitored by 31P{1H} NMR spec-
troscopy at 20 °C, we identified a mixture of 17B and 10 (ratio
80:20). After longer periods, considerable decomposition of
17B is observed. Thus, in 12 h the intensity of the signal due
to 17B decreases, giving a 17B/10 ratio of ∼15:85. In addition,
the 19F NMR spectrum reveals the presence of considerable
amounts of decafluorobiphenyl.
Syn t h esis of [{P t (µ-K(P ):η2-P P h 2CtCBu t )2(µ-η1:η2-
CtCBu t)2}{P t(C6F 5)2}2], 18A. Complex 4 (0.072 g, 0.081
mmol) in CH2Cl2 (10 cm3) was treated with 0.120 g (0.178mmol)
of cis-[Pt(C6F5)2(thf)2] for 3 h. The resulting solution was
evaporated to dryness, and the crude solid (18A + 11 (83:17)
by 31P NMR) was treated with n-hexane, giving 18A as a
nearly pure solid (less than 5% of 11 is detected by 31P NMR).
Yield: 57%. If the initial mixture is stirred for longer periods,
complex 18A decomposes increasing the amount of 11. Thus,
in 7 h, the intensity of the signal due to 11 increases, giving
an 18A/11 ratio of 55:45.
R ea ct ion of cis-[P t (CtCBu t )2L12] (2) w it h cis-[P d -
(C6F 5)2(th f)2] (Mola r Ra tio of 1:2). cis-[Pd(C6F5)2(thf)2]
(0.025 g, 0.043 mmol) was added to a solution of cis-[Pt-
(CtCBut)2(PPh2CtCPh)2] (0.020 g, 0.0215 mmol) in CDCl3 (0.6
cm3), and a 31P NMR spectrum was taken immediately. The
initial 31P{1H} NMR spectrum of this mixture at low temper-
ature (-50 °C) revealed the presence of complex 8 (-8.9 ppm)
as the main component together with the excess of cis-[Pd-
(C6F5)2(thf)2]. When the temperature was increased to room
temperature, considerable decomposition had taken place (Pd
metal) and, in addition to complex 8, small signals at ∼37.6
(d), 33.8 (m), 31.4 (d), and 27.5 (d) ppm were also observed.
The 19F NMR indicated the presence of a considerable amount
of C6F5-C6F5.31
Syn th esis of [{L22P t(µ3-η2CtCP h )2}{P t(C6F 5)2}2], 16B.
To a solution of cis-[Pt(CtCPh)2(PPh2CtCBut)2] (3; 0.100 g,
0.1075 mmol) in CH2Cl2 (10 cm3) was added 0.145 g (0.215
mmol) of cis-[Pt(C6F5)2(thf)2]. After 1 h of stirring, the brown
solution was evaporated to dryness and the residue was
13C NMR (CDCl3, -50 °C): ∼147.6, 144.7, 138.9, 137.9 (br,
C6F5), 135.6-124.6 (Ph), 113.2 (s, Câ, P-CRtCâBut), 108.9 (m,
br, this signal can tentatively be assigned to Câ, -CRtCâBut),
87.18 (dm, signal poorly resolved, CR, -CRtCâBut), 70.5 (d, 1J CP
) 97.1 Hz, CR, P-CRtCâBut), 30.6, 30.4 (s, 2C(CH3)3), 29.7,
29.6 (s, br, CMe3).
i
treated with PrOH (3 cm3) to give a crude solid, which was
washed with n-hexane. The 31P NMR spectra of this solid indi-
cates that complex 16B is contaminated (∼12%) with the dinu-
clear derivative 9. Complex 16B is obtained as a white micro-
crystalline solid by slow crystallization of the crude material
in a CH2Cl2/hexane (1:5) mixture at low temperature (-30 °C).
13C{1H} NMR (CDCl3, -50 °C): 147.4, 144.3, 138.8 (br,
C6F5), 133.8-126.8 (Ph), 121.37 (m, Câ, P-CRtCâBut), 119.7
Rea ction of cis-[P t(CtCBu t)2L22] (4) w ith 2 Equ iv of
cis-[P d (C6F 5)2(th f)2]. The reaction of 4 (0.0152 g, 0.171
mmol) with cis-[Pd(C6F5)2(thf)2] (0.020 g, 0.034 mmol) in CDCl3
(0.6 cm3) was monitored by NMR spectroscopy. The dinuclear
derivative 12 was observed as the only phosphorous-containing
1
(s, Ph), 67.5 (d, J C-P ) 126.7, CR, P-CRtCâBut), 29.3 (s,
C(CH3)3), 28.5 (s, CMe3).
1
platinum complex (31P and H NMR), and no evolution of the
31P{1H} NMR spectrum was observed after 4 or 8 h. The
presence of the excess of “cis-Pd(C6F5)2” (∼-117.3 (Fo), -159.9
(31) Gastinger, R. G.; Anderson, B. B.; Klabunde, K. J . Am. Chem.
Soc. 1980, 102, 4959.

Reactivity of Pt Complexes
Organometallics, Vol. 16, No. 26, 1997 5937
(Fp), -163.5 (Fm)) together with the signals due to C6F5-C6F5
(-137.6 (m), -149.9 (t), -160.4 (m)) (60:40) are visible in the
19F NMR spectra.
the presence of one molecule of n-hexane with an occupancy
of 0.5, one molecule of benzene with an occupancy of 0.3, and
one-half of a molecule of benzene lying around an inversion
center whose three carbon atoms had occupancy 0.3. Both
solvents had been used in the obtention of the crystals. The
interatomic distances and angles were constrained to idealized
geometries, and the anisotropic thermal parameters of the
carbon atoms of each molecule were constrained to be the
same. No attempts to include the solvent hydrogen atoms
were made. For 10‚Me2CO and 16B, no residual peaks higher
than 1 e/Å3 remained in the final density map. For 15A‚
0.5C6H14‚0.45C6H6, the final difference electron density maps
showed eight peaks above 1 e Å-3 (1.08-1.02; largest diff hole
-0.76), all of them located in the solvent area. All calculations
were carried out using the program SHELXL-93.32
X-r a y Cr ysta l Str u ctu r e Deter m in a tion s. Suitable crys-
tals of 10‚Me2CO were grown by slow diffusion of n-hexane
into a Me2CO solution of 10. Suitable crystals of 15A‚0.5C6H14
‚
0.45C6H6 were grown by slow diffusion of n-hexane into a
dichloromethane/benzene solution of 15A. Suitable crystals
of 16B were grown by slow diffusion of n-hexane into a CH2-
Cl2 solution of 16B at -40 °C.
Crystal data and other details of the structure analyses are
presented in Table 7. Selected crystals were fixed on top of
glass or quartz fibers and mounted on the diffractometers. Unit
cell constants were determined from 22 accurately centered
reflections with 24° < 2θ < 26° for 10‚Me2CO, 25 reflections
in the range 22.2° < 2θ < 30.9° for 15A‚0.5C6H14‚0.45C6H6,
and 25 reflections in the range 22.2° < 2θ < 31.8° for 16B.
Data were collected by the ω/2θ scans for 10‚Me2CO and by
ω/θ scans for 15A‚0.5C6H14‚0.45C6H6 and 16B. Three check
reflections were measured at regular intervals, and no loss of
intensity was observed in any case. The position of the heavy
atoms were determined from the Patterson map. The remain-
ing atoms were located in successive difference Fourier
syntheses. H atoms were added at calculated positions (C-H
) 0.96 Å) with an isotropic displacement parameter assigned
1.2 times (for the phenyl groups) or 1.5 times (for the methyl
groups) that of the corresponding C atom. For 10‚Me2CO, a
molecule of insterstitial acetone was found and refined at full
occupancy with anisotropic thermal parameters, and no H
Ack n ow led gm en t. We thank the Direccio´n General
de Investigacio´n Cient´ıfica y Te´cnica (Spain) (Project
Nos. PB 95-0003-C02-01-02 and PB 95-0792) for finan-
cial support. E. Lalinde and M. T. Moreno thank the
University of La Rioja (Spain) for financial support.
Su p p or tin g In for m a tion Ava ila ble: Tables of full atomic
positional and equivalent isotropic displacement parameters,
anisotropic displacement parameters, full bond distances and
bond angles, and hydrogen coordinates and isotropic displace-
ment parameters for the crystal structures of complexes 10,
15A, and 16B (41 pages). Ordering information is given on
any current masthead page.
atoms were added to the acetone molecule. For 15A‚0.5C6H14
‚
0.45C6H6, whereas the positions and thermal parameters of
the atoms of the platinum complex were found and refined
without difficulty, the electron density corresponding to the
solvent molecule atoms was very diffuse. We tried several
models and found that the one which gave best results was
OM970663Y
(32) Sheldrick, G. M. SHELXL-93, a program for crystal structure
determination; University of Go¨ttingen: Go¨ttingen, Germany, 1993.