Syntheses, structures, and electronic and photophysical properties of unsymmetrically substituted butadiynediyl and hexatriynediyl complexes derived from (C6F5)(R3P)2Pt, (p-tol)(R 3P)2Pt, a

Article abstract of DOI:10.1021/om800493x

The CuCl-catalyzed reaction of butadiynyl complex trans-(C ₆F₅)(Et₃P)₂Pt(Cs≡;C) ₂ (6) and trans-(p-tol)(Et₃P)₂PtCl (7) in HNEt₂ affords trans,trans-(C₆F

Full text of DOI:10.1021/om800493x

Organometallics 2008, 27, 4979–4991
4979
Syntheses, Structures, and Electronic and Photophysical Properties
of Unsymmetrically Substituted Butadiynediyl and Hexatriynediyl
Complexes Derived from (C6F5)(R3P)2Pt, (p-tol)(R3P)2Pt, and
(Ph3P)Au End-Groups
Laura de Quadras,† Abigail H. Shelton,‡ Helene Kuhn,† Frank Hampel,†
Kirk S. Schanze,*,‡ and John A. Gladysz*,†,§
Institut fu¨r Organische Chemie and Interdisciplinary Center for Molecular Materials,
Friedrich-Alexander-UniVersita¨t Erlangen-Nu¨rnberg, Henkestrasse 42, 91054 Erlangen, Germany,
Department of Chemistry, UniVersity of Florida, P.O. Box 117200, GainesVille, Florida 32611, and
Department of Chemistry, Texas A&M UniVersity, P.O. Box 30012, College Station, Texas 77842-3012
ReceiVed May 29, 2008
The CuCl-catalyzed reaction of butadiynyl complex trans-(C6F5)(Et3P)2Pt(Ct C)2H (6) and trans-(p-
tol)(Et3P)2PtCl (7) in HNEt2 affords trans,trans-(C6F5)(Et3P)2Pt(Ct C)2Pt(PEt3)2(p-tol) (8; 62%), but similar
reactions of p-tol3P-substituted coupling partners, or of 6 and trans-(p-tol)(p-tol3P)2PtCl (4), are not
successful. However, 6 and 4 react under modified conditions (t-BuOK, KPF6, cat. CuCl, THF/methanol)
to give trans,trans-(C6F5)(Et3P)2Pt(Ct C)2Pt(Pp-tol3)2(p-tol) (9; 91%). The hexatriynyl complexes trans-
(C6F5)(R3P)2Pt(Ct C)3H (R ) p-tol, Et) are treated with 4 and 7, respectively, under the original or
modified conditions. Workups give trans,trans-(C6F5)(R3P)2Pt(Ct C)3Pt(PR3)2(p-tol) (R ) p-tol, 12,
40-63%; Et, 17, 59%). The reaction of 6 and ClAu(PPh3) and KN(SiMe3)2 affords trans-
(C6F5)(Et3P)2Pt(Ct C)2Au(PPh3) (18, 97%). The CuCl-catalyzed reaction of (η5-C5H5)W(CO)3(Ct C)2H
and trans-(C6F5)(Et3P)2PtCl in HNEt2 generates trans-(C6F5)(Et3P)2Pt(Ct C)2W(CO)3(η5-C5H5). The crystal
structures of 8, 9, 17, and 18, or solvates thereof, are determined and analyzed in detail. The square-
planar end-groups in the C4 adducts 8 and 9 define angles of 62.3-34.7°, as opposed to ca. 0° in the C6
adduct 17. Both 9 and 18 exhibit phosphorescence from triplet states concentrated on the C4 segments.
Data with 9 in low-temperature glasses suggest two conformers with different end-group-end-group
orientations.
In most but not all10,11 of our studies, the termini or end-groups
have been identical. However, given a large set of end-groups, there
are many more possible complexes with unlike termini than like
termini. Furthermore, unsymmetrically substituted adducts can
provide enhanced driving forces for many phenomena, such as
metal-to-metal charge and energy transfer. The diversity intrinsic
to such assemblies has been richly exploited by Lapinte in an
extensive series of solo and collaborative synthetic, physical, and
computational studies.11,13a,14c,15
A considerable fraction of our efforts over the past decade
have involved symmetrically substituted diplatinum polyynediyl
complexes,2-9 which are most often prepared by the Hay
oxidative homocoupling protocol exemplified in Scheme 1 (top).
These endeavors have encompassed systems that (a) extend to
as many as 28 sp carbon atoms,3 (b) are “insulated” by a double
helix of sp3 carbon chains,4 (c) contain “bundled” arrays of
Introduction
Our research groups have had an ongoing interest in the
synthesis and detailed physical and chemical characterization
of metal polyynediyl complexes, LyM(Ct C)nMLy.1-11 Such
systems have also attracted the attention of many other
investigators.12-15 These efforts have been motivated by a
variety of fundamental and applied objectives, ranging from
models for the one-dimensional carbon allotrope carbyne to
applications in molecular electronics.
* To whom correspondence should be addressed. Phone: 979-845-
1399 (J.A.G.); 352-392-9133 (K.S.S.). Fax: 979-845-5629 (J.A.G.); 202-
513-8648(K.S.S). E-mail:gladysz@mail.chem.tamu.edu(J.A.G.);kschanze@
chem.ufl.edu (K.S.S).
† Universita¨t Erlangen-Nu¨rnberg.
‡ University of Florida.
§ Texas A&M University.
(1) (a) Brady, M.; Weng, W.; Zhou, Y.; Seyler, J. W.; Amoroso, A. J.;
Arif, A. M.; Bo¨hme, M.; Frenking, G.; Gladysz, J. A. J. Am. Chem. Soc.
1997, 119, 775. (b) Dembinski, R.; Bartik, T.; Bartik, B.; Jaeger, M.;
Gladysz, J. A. J. Am. Chem. Soc. 2000, 122, 810. (c) Meyer, W. E.;
Amoroso, A. J.; Horn, C. R.; Jaeger, M.; Gladysz, J. A. Organometallics
2001, 20, 1115. (d) Horn, C. R.; Gladysz, J. A. Eur. J. Inorg. Chem. 2003,
9, 2211.
(6) (a) Stahl, J.; Mohr, W.; de Quadras, L.; Peters, T. B.; Bohling, J. C.;
Mart´ın-Alvarez, J. M.; Owen, G. R.; Hampel, F.; Gladysz, J. A. J. Am.
Chem. Soc. 2007, 129, 8282. (b) de Quadras, L.; Bauer, E. B.; Mohr, W.;
Bohling, J. C.; Peters, T. B.; Mart´ın-Alvarez, J. M.; Hampel, F.; Gladysz,
J. A. J. Am. Chem. Soc. 2007, 129, 8296. (c) de Quadras, L.; Bauer, E. B.;
Stahl, J.; Zhuravlev, F.; Hampel, F.; Gladysz, J. A. New J. Chem. 2007,
31, 1594. (d) Owen, G. R.; Stahl, J.; Hampel, F.; Gladysz, J. A. Chem.-
Eur. J. 2008, 14, 73.
(2) Mohr, W.; Stahl, J.; Hampel, F.; Gladysz, J. A. Chem.-Eur. J. 2003,
9, 3324.
(3) Zheng, Q.; Bohling, J. C.; Peters, T. B.; Frisch, A. C.; Hampel, F.;
Gladysz, J. A. Chem.-Eur. J. 2006, 12, 6486.
(4) Owen, G. R.; Hampel, F.; Gladysz, J. A. Organometallics 2004,
23, 5893.
(5) Zheng, Q.; Hampel, F.; Gladysz, J. A. Organometallics 2004, 23,
5896.
(7) Stahl, J.; Bohling, J. C.; Peters, T. B.; de Quadras, L.; Gladysz, J. A.
Pure Appl. Chem. 2008, 80, 459.
(8) Silverman, E. E.; Cardolaccia, T.; Zhao, X.; Kim, K.-Y.; Haskins-
Glusac, K.; Schanze, K. S. Coord. Chem. ReV. 2005, 249, 1491.
(9) Farley, R. T.; Zheng, Q.; Gladysz, J. A.; Schanze, K. S. Inorg. Chem.
2008, 47, 2955.
10.1021/om800493x CCC: $40.75
2008 American Chemical Society
Publication on Web 09/13/2008

4980 Organometallics, Vol. 27, No. 19, 2008
de Quadras et al.
Scheme 1. Previously Investigated Coupling Routes to Symmetrically Substituted Diplatinum Polyynediyl Complexes
parallel sp chains,5 and (d) have been longitudinally extended
to PtCxPtCxPtCxPt species.6 In all of these cases, the end-groups
have been identical.
raynediyl complexes can be prepared by Hay homocouplings
of the corresponding monoplatinum butadiynyl complexes.2,3,6b,c,7
In contrast, analogous reactions of the ethynyl complexes trans-
Accordingly, we set out to test various approaches to
achieving unsymmetrically substituted diplatinum polyynediyl
complexes or heterobimetallic analogues with one non-platinum
end-group and briefly probe their structural, electronic, and
photophysical properties. These efforts are narrated below, and
additional details are available elsewhere.16
(13) Selected lead papers to a now-immense literature: (a) Lapinte, C.
J. Organomet. Chem. 2008, 693, 793. (b) Bruce, M. I.; Low, P. J.; Costuas,
K.; Halet, J.-F.; Best, S. P.; Heath, G. A. J. Am. Chem. Soc. 2000, 122,
1949. (c) Xu, G.-L.; Zou, G.; Ni, Y.-H.; DeRosa, M. C.; Crutchley, R. J.;
Ren, T. J. Am. Chem. Soc. 2003, 125, 10057. (d) Akita, M.; Sakurai, A.;
Chung, M.-C.; Moro-oka, Y. J. Organomet. Chem. 2003, 670, 2. (e)
Venkatesan, K.; Fox, T.; Schmalle, H. W.; Berke, H. Organometallics 2005,
24, 2834. (f) Qi, H.; Gupta, A.; Noll, B. C.; Snider, G. L.; Lu, Y.; Lent, C.;
Fehlner, T. P. J. Am. Chem. Soc. 2005, 127, 15218.
Results
(14) Heterobimetallic polyynediyl complexes especially relevant to this
study: (a) Antonova, A. B.; Bruce, M. I.; Ellis, B. G.; Gaudio, M.;
Humphrey, P. A.; Jevric, M.; Melino, G.; Nicholson, B. K.; Perkins, G. J.;
Skelton, B. W.; Stapleton, B.; White, A. H.; Zaitseva, N. N. Chem. Commun.
2004, 960. (b) Bruce, M. I.; Hall, B. C.; Low, P. J.; Smith, M. E.; Skelton,
B. W.; White, A. H. Inorg. Chim. Acta 2000, 300-302, 633. (c) Bruce,
M. I.; Costuas, K.; Davin, T.; Ellis, B. G.; Halet, J.-F.; Lapinte, C.; Low,
P. J.; Smith, M. E.; Skelton, B. W.; Toupet, L.; White, A. H. Organome-
tallics 2005, 24, 3864. (d) Bruce, M. I.; Jevric, M.; Skelton, B. W.; Smith,
M. E.; White, A. H.; Zaitseva, N. N. J. Organomet. Chem. 2006, 691, 361.
(15) Other literature especially relevant to this study: (a) Coat, F.;
Guillevic, M.-A.; Toupet, L.; Paul, F.; Lapinte, C. Organometallics 1997,
16, 5988. (b) Coat, F.; Guillemot, M.; Paul, F.; Lapinte, C. J. Organomet.
Chem. 1999, 578, 76.
1. Syntheses of Diplatinum Butadiynediyl Complexes. As
summarized in Scheme 1 (top), many diplatinum octatet-
(10) (a) Weng, W.; Bartik, T.; Brady, M.; Bartik, B.; Ramsden, J. A.;
Arif, A. M.; Gladysz, J. A. J. Am. Chem. Soc. 1995, 117, 11922. (b) Falloon,
S. B.; Szafert, S.; Arif, A. M.; Gladysz, J. A. Chem.-Eur. J. 1998, 4, 1033.
(11) (a) Paul, F.; Meyer, W. E.; Toupet, L.; Jiao, H.; Gladysz, J. A.;
Lapinte, C. J. Am. Chem. Soc. 2000, 122, 9405. (b) Jiao, H.; Costuas, K.;
Gladysz, J. A.; Halet, J.-F.; Guillemot, M.; Toupet, L.; Paul, F.; Lapinte,
C. J. Am. Chem. Soc. 2003, 125, 9511. (c) Szafert, S.; Paul, F.; Meyer,
W. E.; Gladysz, J. A.; Lapinte, C. C. R. Chem. 2008, 11, 693.
(12) Review literature:(a) Bruce, M. I.; Low, P. J. AdV. Organomet.
Chem. 2004, 50, 179. (b) Szafert, S.; Gladysz, J. A. Chem. ReV 2003, 103,
4175; 2006, 106, PR1-PR33.
(16) de Quadras, L. Doctoral Dissertation, Universita¨t Erlangen-Nu¨rn-
berg, 2006.

Unsymmetrically Substituted Butadiynediyl and Hexatriynediyl Complexes
Organometallics, Vol. 27, No. 19, 2008 4981
Scheme 2. Attempted Syntheses of Unsymmetrically
Substituted Diplatinum Butadiynediyl Complexes
Scheme 3. Syntheses of Unsymmetrically Substituted Diplati-
num Butadiynediyl Complexes
(C6F5)(R3P)2PtCt CH (Scheme 1, middle) do not yield signifi-
cant quantities of butadiynediyl complexes.7,17 Possible under-
lying steric and electronic factors are analyzed below. However,
two such complexes have been isolated in high yields by
Hagihara heterocouplings18 of the butadiynyl complexes trans-
(Ar)(R3P)2Pt(Ct C)2H and chloride complexes trans-(Ar)(R3P)2-
PtCl, using the basic solvent HNEt2 and a catalytic amount of
Table 1. Cyclic Voltammetry Dataa
complex
Ep,a [V]
Ep,c [V]
E° [V]
∆E [V]
ic/a
CuCl or CuI (I and II in Scheme 1, bottom).2,7,19
8
9
0.845
0.827
1.040
1.011
1.268
0.940
1.035
1.156
0.855
0.772
0.757
0.963
0.919
0.809
0.792
1.001
0.965
73
70
77
92
0.91
0.78
0.27
0.25
Thus, as summarized in Scheme 2, equimolar quantities of
the p-tolyl- and pentafluorophenyl-substituted butadiynyl and
chloride complexes trans-(p-tol)(p-tol3P)2Pt(Ct C)2H (1)3 and
trans-(C6F5)(p-tol3P)2PtCl (2),2 or the “opposite” combination
trans-(C6F5)(p-tol3P)2Pt(Ct C)2H (3)2 and trans-(p-tol)(p-
tol3P)2PtCl (4),3 were combined under various Hagihara condi-
tions. However, NMR monitoring showed the concomitant
decomposition of one or both reaction partners, and only traces
of the target complex trans,trans-(p-tol)(p-tol3P)2Pt(Ct C)2Pt(Pp-
tol3)2(C6F5) (5) could be detected by mass spectrometry.
Additional details are supplied elsewhere.16
12
17
18
Ib
0.862
0.957
1.066
0.901
0.996
1.111
78
78
90
0.98
0.91
0.71
IIc
IIId
IVe
a Conditions: 3-5 × 10-4 M, n-Bu4N+BF4-/CH2Cl2 at 22.5 ( 1 °C;
Pt working and counter electrodes, potential vs Ag wire pseudo-
reference; scan rate 100 mV s-1; ferrocene ) 0.46 V. b Data from ref
22. c Data from ref 17. d Data from ref 6d. e Data from ref 3.
Structural data (below) suggest that the effective steric bulk
of Et3P ligands in symmetrically substituted diplatinum poly-
ynediyl complexes is much less than that of Ar3P ligands.6d
Thus, a reaction analogous to that of 3 and 4 in Scheme 2 was
conducted, but with the Et3P complexes trans-(C6F5)(Et3P)2-
Pt(Ct C)2H (6)7 and trans-(p-tol)(Et3P)2Pt(Cl) (7).7 As shown
in Scheme 3 (top), the target butadiynediyl complex trans,trans-
(C6F5)(Et3P)2Pt(Ct C)2Pt(PEt3)(p-tol) (8) could be isolated as
an off-white powder in 62% yield after workup.
Complex 8 and all isolable new compounds below were
characterized by IR, NMR (1H, 13C, 31P), and UV-visible
spectroscopy, mass spectrometry, cyclic voltammetry, DSC,
TGA, and microanalysis. The cyclic voltammetry results are
provided in Table 1, and the other data in the Experimental
Section. All complexes were stable for extended periods in
air, with TGA traces showing no appreciable mass losses
below 200 °C. The 13C and 31P NMR spectra of the
diplatinum complexes resembled hybrids of the symmetrically
(17) Stahl, J. Doctoral Dissertation, Universita¨t Erlangen-Nu¨rnberg, 2003.
(18) (a) Sonogashira, K.; Fujikura, Y.; Yatake, T.; Toyoshima, N.;
Takahashi, S.; Hagihara, N. J. Organomet. Chem. 1978, 145, 101. (b)
Ogawa, H.; Onitsuka, K.; Joh, T.; Takahashi, S.; Yamamoto, Y.; Yamakazi,
H. Organometallics 1988, 7, 2257, and earlier papers cited therein.
(19) Curiously, this heterocoupling fails with trans-(p-tol)(p-tol3P)2Pt
end-groups (cat. CuI or CuCl at RT to 40 °C): Zheng, Q. Unpublished data
including final research report, Universita¨t Erlangen-Nu¨rnberg, 2006.
1
substituted complexes I-IV. The JPPt values (2406-2987
Hz), which are diagnostic of stereochemistry,20 confirmed
the formation of trans isomers.
(20) Grim, S. O.; Keiter, R. L.; McFarlane, W. Inorg. Chem. 1967, 6,
1133.

4982 Organometallics, Vol. 27, No. 19, 2008
de Quadras et al.
Scheme 4. Syntheses of Unsymmetrically Substituted
Diplatinum Hexatriynediyl Complexes
Given this success, mixed Et3P/Ar3P systems were targeted.
As shown in Scheme 3 (bottom), an analogous reaction of 6
and 4 did not afford detectable quantities of the butadiynyl
complex trans,trans-(C6F5)(Et3P)2Pt(Ct C)2Pt(Pp-tol3)2(p-tol)
(9). However, couplings of terminal alkynes and butadiynyl
complexes with metal halides have also been effected using
KPF6/t-BuOK in place of HNEt2.11a,c,15 Thus, the reaction of 6
and 4 was carried out in the presence of a slight excess of
t-BuOK and KPF6 and a catalytic amount of CuCl in a mixture
of THF and methanol. The target complex 9 was isolated as a
pale yellow solid in 91% yield after workup.
2. Syntheses of Diplatinum Hexatriynediyl Complexes.
Analogous routes to diplatinum hexatriynediyl complexes were
investigated next. Since monoplatinum hexatriynyl complexes
are labile and store poorly, they were generated in situ from
the corresponding triethylsilylhexatriynyl complexes by an
established protocol involving wet n-Bu4N+F- in CH2Cl2.2,3
As shown in Scheme 4 (bottom), the p-tolyl-substituted hexa-
triynyl complex trans-(p-tol)(p-tol3P)2Pt(Ct C)3H (11)3 was
combined with the pentafluorophenyl-substituted chloride com-
plex 2 under Hagihara conditions. However, the target complex
trans,trans-(p-tol)(p-tol3P)2Pt(Ct C)3Pt(Pp-tol3)2(C6F5) (12) could
not be detected by NMR or mass spectrometry. NMR data
suggested that 11 decomposed faster than it underwent hetero-
coupling.16
The “opposite” reactant combination was therefore investi-
gated. As shown in Scheme 4 (top), the pentafluorophenyl-sub-
stituted butadiynyl complex trans-(C6F5)(p-tol3P)2Pt(Ct C)3H
(14)2 was combined with the p-tolyl-substituted chloride
complex 4 under analogous conditions. Workup gave the
hexatriynediyl complex 12 as a yellow powder in 40% yield.
When the modified protocol used for 9 in Scheme 3 was
employed (KPF6/t-BuOK/methanol/THF in place of HNEt2), the
yield increased to 63%. This protocol was also employed in a
sequence conducted with the Et3P complexes trans-(C6F5)-
(Et3P)2Pt(Ct C)3SiEt3 (15)7 and 7 (Scheme 4, top). Workup gave
the target complex trans,trans-(C6F5)(Et3P)2Pt(Ct C)3Pt(PEt3)2-
(p-tol) (17) as a yellow powder in 59% yield.
3. Syntheses of Heterobimetallic Polyynediyl Com-
plexes. Under appropriate conditions, gold polyynyl complexes
readily couple with I(Ct C)nI or LyM(Ct C)nI species.14a,21
Hence, they constitute valuable building blocks for the synthesis
of compounds with longer sp carbon chains. Accordingly, efforts
were directed at Pt(Ct C)nAu assemblies, which have a very
limited literature.22 A variety of recipes have been used to attach
(Ar3P)Au end-groups to terminal alkynes.14d As shown in
Scheme 5 (top), the sequential treatment of the butadiynyl
complex 6 with the chloride complex (Ph3P)AuCl23 and then
the base KN(SiMe3)2 gave the target complex trans-
(C6F5)(Et3P)2Pt(Ct C)2Au(PPh3) (18) as a yellow powder in
97% yield after workup. Reactions under Hagihara conditions
gave complex mixtures of products. In accord with literature
precedent,14d The AuCC 13C NMR signals of 18 were strongly
coupled to phosphorus (JCP ) 143 and 30 Hz), with the former
considerably downfield of the PtC signal (116.6 vs 93.7 ppm).
The tungsten chloride complex (η5-C5H5)(CO)3WCl (21)24
reacts with terminal alkynes and butadiyne under Hagihara
conditions to give alkynyl complexes.25 However, as shown in
Scheme 5 (bottom), analogous reactions with the butadiynyl
complex 6 did not give detectable quantities of the target
complex trans-(C6F5)(Et3P)2Pt(Ct C)2W(CO)3(η5-C5H5) (22).
The tungsten butadiynyl complex (η5-C5H5)(CO)3W(Ct C)2H
(23)25 similarly condenses with various metal chloride com-
plexes under Hagihara-type conditions.14c Thus, as shown in
Scheme 5 (bottom), the reaction of 23 and the platinum chloride
complex 2 was carried out under standard conditions. Alumina
filtration gave 22 as a yellow powder, as assigned by a parent
(21) Antonova, A. B.; Bruce, M. I.; Humphrey, P. A.; Gaudio, M.;
Nicholson, B. K.; Scoleri, N.; Skelton, B. W.; White, A. H.; Zaitseva, N. N.
J. Organomet. Chem. 2006, 691, 4694.
(22) (a) Bruce, M. I.; Costuas, K.; Halet, J.-F.; Hall, B. C.; Low, P. J.;
Nicholson, B. K.; Skeleton, B. W.; White, A. H. J. Chem. Soc., Dalton
Trans. 2002, 383. (b) Bruce, M. I.; Hall, B. C.; Skeleton, B. W.; Smith,
M. E.; White, A. H. J. Chem. Soc., Dalton Trans. 2002, 995. (c) See
also: Vicente, J.; Chicote, M.-T.; Alvarez-Falco´n, M. M. Organometallics
2005, 24, 2764.
(24) Hoffman, N. W. Inorg. Chim. Acta 1984, 88, 59.
(25) Bruce, M. I.; Ke, M.; Low, P. J.; Skelton, B. W.; White, A. H.
Organometallics 1998, 17, 3539.
(23) Bruce, M. I.; Nicholson, B. K.; Bin Shawkataly, O. Inorg. Synth.
1989, 26, 324.

Unsymmetrically Substituted Butadiynediyl and Hexatriynediyl Complexes
Organometallics, Vol. 27, No. 19, 2008 4983
Scheme 5. Syntheses of Heterobimetallic Butadiynediyl
Complexes
Figure 1. Thermal ellipsoid (top; 50% probability level), Newman
(middle), and space-filling (bottom) representations of 8.
The bond lengths and angles in 8, 9, 17, and 18 were
unexceptional and close to those of symmetrically substituted
diplatinum analogues.2-6 The Ct C and C-C bond lengths fell
in the typical ranges of 1.119-1.224 and 1.356-1.400 Å,
respectively. The sp carbon chains were, as is normal for
polyynes12c and other compounds in this series,2-6,26 slightly
curved. This feature is analyzed in greater detail elsewhere,16
and additional structural properties are discussed below.
5. Photophysics of the PtC4Pt′ and PtC4Au Complexes
9 and 18. The butadiynediyl complexes 9 and 18, which feature
one common end-group, were selected for a comparative
photophysical study. Absorption, emission, and emission excita-
tion spectra were first recorded, as depicted in Figure 5. The
absorption spectra were obtained from 2-methyltetrahydrofuran
(MTHF) solutions at ambient temperature, whereas the emission
experiments were conducted at 80 K in a MTHF glass.
ion in the mass spectrum, a 31P NMR spectrum showing one
main signal (12.8 ppm, 1JPPt ) 2431 Hz, 80% of total integral),
and a 13C NMR spectrum with peaks appropriate for WCt and
PtCt signals (116.4, 93.9 ppm). However, all attempts to further
purify 22 by column chromatography or crystallization were
unsuccessful.
4. Crystal Structures. Crystals of 8, 9, 17, and 18, or
solvates thereof, that were suitable for X-ray diffraction could
be obtained. The structures were solved as described in the
Experimental Section and Table 2. That of 8 was disordered
over two positions in which the pentafluorophenyl and p-tolyl
ligands were nearly coincident, but occupancy could be refined
to a 73:27 ratio. Thermal ellipsoid, space-filling, and other
representations of the molecular structures are depicted in
Figures 1-4, and packing diagrams are provided elsewhere.16
Key metrical parameters are summarized in Tables 3 and 4.
End-group/end-group angles were quantified by two sets of
planes (Table 3) as described in previous papers.2,3,6 Two
independent molecules of 18 were present in the unit cell, but
exhibited only minor differences in the conformations of the
end-groups.
In accord with earlier computational data,27 the UV absorp-
tions were presumed to be dominated by π,π* transitions of
the butadiynediyl segments. Close comparison of the spectra
showed that absorption of the diplatinum complex 9 extended
(26) (a) Bohling, J. C.; Peters, T. B.; Arif, A. M.; Hampel, F.; Gladysz,
J. A. In Coordination Chemistry at the Turn of the Century; Ondrejovic¸,
G., Sirota, A. Eds.; Slovak Technical University Press: Bratislava, Slovakia,
1999; pp 47-52. (b) Peters, T. B.; Zheng, Q.; Stahl, J.; Bohling, J. C.;
Arif, A. M.; Hampel, F.; Gladysz, J. A. J. Organomet. Chem. 2002, 641,
53. (c) Mohr, W.; Peters, T. B.; Bohling, J. C.; Hampel, F.; Arif, A. M.;
Gladysz, J. A. C. R. Chem. 2002, 5, 111.
(27) Zhuravlev, F.; Gladysz, J. A. Chem.-Eur. J. 2004, 10, 6510.

4984 Organometallics, Vol. 27, No. 19, 2008
de Quadras et al.
Table 2. Summary of Crystallographic Dataa
8
9 · CH2Cl2
17
C43H67F5P4Pt2
1193.03
monoclinic
P21/n
18 · (C7Hg)0.5
empirical formula
fw
C41H71F5P4Pt2
1173.04
C72H81Cl2F5P4Pt2
1626.33
C43.50H49AuF5P3Pt
1151.79
triclinic
cryst syst
space group
unit cell dimen
a [Å]
b [Å]
c [Å]
R [deg]
ꢀ [deg]
γ [deg]
V [Å3]
monoclinic
P21/n
triclinic
P1
j
j
P1
9.0267(4)
36.3908(2)
14.5404(8)
90
96.838(2)
90
4742.4(3)
4
11.97090(10)
17.7039(2)
18.2489(2)
78.3350(10)
88.1700(10)
72.1490(10)
3481.30(6)
4
13.5959(2)
11.4504(2)
30.6720(5)
90
90.788(1)
90
4774.52(13)
4
1.660
12.6692(4)
13.6709(3)
25.2832(8)
78.011(2)
87.011(1)
89.648
4277.6(2)
4
1.788
6.856
Z
Fcalcd [Mg m-3
]
1.643
6.074
2312
1.551
4.236
1616
µ [mm-1
F(000)
]
6.035
2344
2228
cryst size, mm
θ range [deg]
index ranges (h,k,l)
no. reflns collected
0.20 × 0.20 × 0.20
1.12 to 27.45
-11,11; -47,43; -18,18
11853
0.25 × 0.20 × 0.15
1.53 to 27.48
-15,15; -21,22; -23,23
30543
0.20 × 0.20 × 0.10
1.33 to 27.51
-17,17; -14,14; -39,39
20405
0.20 × 0.20 × 0.01
1.52 to 25.04
-15,15; -15,16; -30,30
24331
no. indep reflns
8928 [R(int) ) 0.0258]
15 929 [R(int) ) 0.0219]
10 873 [R(int) ) 0.0251]
14 421 [R(int) ) 0.0386]
no. reflns [I > 2 σ(I)]
max. and min. transmn
no. data/restraints/params
goodness-of-fit on F2
final R indices [I > 2σ(I)]
R indices (all data)
6339
13 090
7454
8280
0.3763 and 0.3763
8928/2/500
1.113
0.5691 and 0.4173
15 929/25/777
1.040
0.5836 and 0.3782
10 873/0/500
1.082
0.9346 and 0.3409
14 421/0/1003
0.967
R1 ) 0.0464, wR2 ) 0.1099 R1 ) 0.0275 wR2 0.0696
R1 ) 0.0839, wR2 ) 0.1442 R1 ) 0.0390, wR2 ) 0.0776 R1 ) 0.0529, wR2 ) 0.0946 R1 ) 0.0959, wR2 ) 0.1367
1.297 and -1.764 1.401 and -1.280 0.907/-1.757 1.926 and -1.534
R1 ) 0.0303 wR2 ) 0.0749 R1 ) 0.0460 wR2 ) 0.1127
largest diff peak/hole [e Å-3
]
a Data common to all structures: temp of collection, 173(2) K; λ, 0.71073 Å; refinement method, full-matrix least-squares on F2; Bruker-AXS Smart
1000 diffractometer.
Table 3. Key Interatomic Distances (Å) and Angles (deg) for
Diplatinum Complexes
Table 4. Key Interatomic Distances (Å) and Angles (deg) for
18 · (C7H8)0.5
a
8a
9 · CH2Cl2
17
molecule 1
molecule 2
Pt1 · · · Pt2
7.742 (6)
7.833
7.759
7.830
10.3628 (3)
10.293
Pt1 · · · Au
7.787
7.792
7.788
7.794
sum of all bond lengths
from Pt1 to Pt2
Pt1-C1
sum of all bond
lengths from Pt to Au
Pt1-C1
2.009 (11)
1.202 (14)
1.400 (14)
1.196 (13)
1.988 (4)
1.225 (5)
1.373 (5)
1.221 (5)
1.995 (5)
1.119 (6)
1.367 (6)
1.215 (7)
1.373 (7)
1.216 (6)
2.008 (5)
2.055 (5)
2.062 (5)
2.2998 (11)
2.2907 (11)
2.2864 (11)
2.2986 (12)
176.9 (4)
178.0 (5)
178.5 (5)
178.7 (6)
179.3 (5)
176.8 (4)
1.5
2.003 (11)
1.213 (13)
1.368 (15)
1.218 (13)
1.990 (10)
2.107 (10)
2.304 (2)
2.302 (2)
2.272 (3)
177.3 (9)
178.5 (11)
178.1 (11)
178.5 (9)
176.7 (2)
1.988 (10)
1.221 (13)
1.356 (15)
1.222 (13)
2.007 (11)
2.081 (9)
2.301 (2)
2.307 (2)
2.279 (3)
177.2 (8)
179.5 (11)
178.0 (11)
176.4 (9)
177.1 (2)
C1t C2
C2-C3
C3t C4
C4-C5
C5t C6
C1t C2
C2-C3
C3t C4
C4-Au
Pt-C11ipso
Pt1-P1
Pt1-P2
Au-P3
Pt1-C1-C2
C1-C2-C3
C2-C3-C4
C3-C4-Au
C4-Au-P3
C4(C6)-Pt2
Pt1-C11ipso
Pt2-C21ipso
Pt1-P1
2.026 (9)
2.081 (11)
2.075 (9)
2.300 (3)
2.291 (3)
2.295 (3)
2.287 (2)
172.5 (8)
173.8 (10)
175.6 (11)
2.024 (3)
2.078 (4)
2.059 (3)
2.2899 (10)
2.2987 (8)
2.2850 (8)
2.2976 (9)
173.2 (3)
177.4 (4)
176.1 (4)
Pt1-P2
Pt2-P3
Pt2-P4
Pt1-C1-C2
C1-C2-C3
C2-C3-C4
C3-C4-C5
C4-C5-C6
C3(C5)-C4(C6)-Pt2
P-Pt-P/Pt angleb
Pt-P-P-Cipso-C1 angleb
triplet state concentrated on the butadiynediyl segments. This
is supported by the lifetimes, which were ca. 6.5 and 15 µs for
9 and 18, respectively. The emission spectra for both complexes
appeared as a manifold of narrow vibronic sub-bands separated
by approximately 2200 cm-1. This progression was attributed
to the stretching mode of the butadiynediyl chains. Utilizing
methods described in previous papers,9,28 the phosphorescence
spectra for 9 and 18 at 80 K were analyzed by a single-mode
Franck-Condon expression,
174.1 (9)
62.3
60.1
171.2 (3)
35.1
34.7
5.1
a The atomic numbering sequence C11-Pt1-C1-C2-C3-C4-Pt2-
C21 has been reversed from that in the CIF file to facilitate comparisons
with the other complexes. b Angle between the planes defined by these
atoms on each end-group.
to longer wavelengths than the platinum/gold complex 18. This
feature suggested a greater degree of π-delocalization in the
former. Complex 18 also exhibited a very intense UV transition
at 280 nm. Given the absence of a counterpart in 9, this was
presumed to be associated with the Ph3PAuC4 moiety.
At room temperature, neither 9 or 18 exhibited emission.
However, at low temperature in a MTHF glass, both complexes
showed a bright and highly structured emission (Figures 5b and
5d). The emission was assigned to phosphorescence from a
E00 - νmpωm 3(Sm)νm
5
I(ν) )
×
∑
{
(
)
E00
νm!
νm)0
2
ν - E00 + νmpωm
∆ν0,1⁄2
exp -4 ln 2
(1)
}
(
)
[
]
where I(ν) is the relative emission intensity at energy ν, E00 is the
energy of the 0-0 transition, νm is the quantum number of the

Unsymmetrically Substituted Butadiynediyl and Hexatriynediyl Complexes
Organometallics, Vol. 27, No. 19, 2008 4985
Figure 3. Thermal ellipsoid (top; 50% probability level) and space-
filling (bottom) representations of 17.
Figure 2. Thermal ellipsoid (top; 50% probability level), Newman
(middle), and space-filling (bottom) representations of 9.
average medium-frequency vibrational mode, pωm is the average
medium-frequency acceptor modes coupled to the triplet-excited-
state to ground-state transition, Sm is the Huang-Rhys factor, and
∆ν0,1/2 is the half-width of the individual vibronic bands. The
experimental emission spectra were fitted using a macro in
Microsoft Excel.9 A summary of the parameters recovered from
the fits is provided in Table 5.
Several interesting features emerge from Table 5. First, the
0-0 emission energy for the PtC4Au complex 18 is ca. 900
cm-1 higher than that for the PtC4Pt′ complex 9. Second, the
Huang-Rhys parameter (Sm) is noticeably smaller for the latter.
Both of these features are consistent with the notion that the
triplet wave function is spatially more concentrated in the
platinum/gold system. Excitation spectra were recorded while
monitoring the 0-0 emission band (80 K), as depicted as
overlays with the absorption spectra in Figures 5a and 5c. The
excitation spectra reflect the absorption spectra, except that
the vibronic structure is better resolved. This is likely due to
the frozen glass matrix.
Figure 4. Thermal ellipsoid (top; 50% probability level) and space-
filling (bottom) representations of 18.
The emission spectra were next studied as a function of
temperature from 80 K to room temperature. For 18, the
spectra were unaffected by increasing temperature and only
the intensity decreased. However, an interesting feature
emerged with 9. At 80 K in the frozen glass, the spectrum
(28) Whittle, C. E.; Weinstein, J. A.; George, M. W.; Schanze, K. S.
Inorg. Chem. 2001, 40, 4053.

4986 Organometallics, Vol. 27, No. 19, 2008
de Quadras et al.
Table 5. Emission Spectral Fitting Parameters for the PtC4Pt′ and PtC4Au Complexes 9 and 18 at 80 K
complex
λ
abs/nm (ε/M-1 cm-1 a
)
λmax, em
E00/cm-1
pω/cm-1
∆ν0.1/2/cm-1
Sm
τ/µs
9
279 (25000)
326 (14000)
352 (13000)
280 (55000)
297 (52000)
325 (14000)
432
23 150
2184
480
0.78
6.49 ( 0.10
18
416
24 035
2158
335
1.03
14.9 ( 1.85
a Recorded in 2-methyltetrahydrofuran (MTHF) at room temperature.
Figure 5. (a) Absorption (solid line; room temperature) and excitation (dashed line, 81 K, λem ) 418 nm) spectra of 9 in MTHF (2-
methyltetrahydrofuran). (b) Emission spectrum of 9 (81 K, λex ) 352 nm). (c) Absorption (solid line; room temperature) and excitation
(dashed line, 81 K, λem ) 416 nm) spectra of 18 in MTHF. (d) Emission spectrum of 18 (81 K, λex ) 325 nm).
Figure 6. (a) Excitation spectra of 9 (81 K, MTHF), λem ) 418 nm (dashed line) and λem ) 432 nm (solid line). (b) Variable-temperature
emission spectra of 9 (λex ) 326 nm) in order of decreasing intensity: 80, 88, 91, 96, 102, 107, 110, 117, 121, 125 K.
varied with excitation wavelength. The spectrum shown in
Figure 5b was obtained with 352 nm excitation, coincident
with the maximum in the excitation spectrum in Figure 5a.
A substantially different spectrum was observed when the
80 K sample was excited at shorter wavelength (e.g., 326
nm, Figure 6b). In this case, the emission showed two distinct
vibronic progressions, suggesting the existence of heteroge-
neity. Figure 6a compares the emission excitation spectra of
9 obtained at the peaks of the two 0-0 bands in the emission
spectra. It can easily be seen that the higher energy emission
has an excitation profile that is blue-shifted compared to that
of the more intense, lower energy emission. Finally, and
especially noteworthy, upon warming the sample above the
solvent glass-fluid transition temperature (120 K), the high
energy progression disappeared, and the emission was
dominated only by the single 0-0 band and vibronic
progression characteristic of the diplatinum complex. A
rationale for these observations involving two distinct triplet
conformers is proposed below.
Discussion
1. Syntheses of Title Complexes. As summarized in Scheme
1 (bottom), prior to this study we had been able to prepare two

Unsymmetrically Substituted Butadiynediyl and Hexatriynediyl Complexes
Organometallics, Vol. 27, No. 19, 2008 4987
Figure 7. Space-filling representations of I and III (top and bottom)
and a Newman projection of I (middle).
Figure 9. Thermal ellipsoid (top; 50% probability level), Newman
(middle), and space-filling (bottom) representations of trans,trans-
I(Me3P)2PtCt CPt(PMe3)2I.
symmetrically substituted butadiynediyl complexes by Hagihara
heterocouplings, C6F5/p-tol3P-substituted I2 and C6F5/Et3P-
substituted II,7 as well as analogous C6F5/p-tol3P- and p-tol/p-
tol3P-substituted hexatriynediyl (III, IV) and p-tol/p-tol3P-
substituted decapentaynediyl (V) complexes.2,3 These results,
together with the successful and unsuccessful syntheses of
unsymmetrically substituted homologues in Schemes 2-4 and
related data, suggest that steric and electronic factors play key
roles in these couplings. For example, note that as the lengths
of the polyynyl ligands in Scheme 1 (bottom) increase, lower
temperatures can be employed. Progressively lower temperatures
also suffice for the homocouplings in Scheme 1 (top).2,3 The
Brønsted acidities of terminal polyynes, which may be of
mechanistic relevance, are known to increase with the sp chain
length.29
Scheme 2 shows that despite the successful synthesis of
I, all attempts to prepare a homologue in which one
pentafluorophenyl ligand has been replaced by p-tolyl have
been unsuccessful. For reference, a space-filling representa-
tion of the crystal structure of I6d is shown in Figure 7 (top).
This dramatically illustrates the steric interactions between
the end-groups, which intimately embrace. In contrast, there
are no end-group/end-group steric interactions in the ho-
mologous hexatriynediyl complex III (Figure 7, bottom).6d
The hexatriynediyl complex with PEt3 ligands has also been
structurally characterized, and the van der Waals separation
of the end-groups is even greater.6d
Accordingly, Scheme 2 shows that unsymmetrically sub-
stituted butadiynediyl complexes are easily accessed when
the p-tol3P ligands on one or both end-groups are replaced
by Et3P ligands. As would be intuitively expected from the
Figure 8. Thermal ellipsoid (top; 50% probability level), Newman
(middle), and space-filling (bottom) representations of trans,trans-
Cl(Ph3P)2PtCt CPt(PPh3)2Cl.

4988 Organometallics, Vol. 27, No. 19, 2008
de Quadras et al.
results in Scheme 1 (bottom), Scheme 4 establishes that
unsymmetrically substituted hexatriynediyl complexes can
be prepared with either p-tol3P or Et3P ligands. However,
we do not presently have a rationale for our inability to cross-
couple 11 and 4 (Scheme 4, bottom). In principle, certain
complexes might be accessed by alternative combinations
of coupling partners (e.g., trans-(p-tol)(R3P)2Pt(Ct C)2H and
trans-(C6F5)(Et3P)2PtCl for 8 and 9 (Scheme 3)), but such
details were beyond the scope of this initial exploratory study.
in an impressive 94% yield from a reaction of the chloroethynyl
complex trans-Cl(Ph3P)2PtCt CCl and the ethylene adduct of
Pt(PPh3)2, a method that would not be applicable to the title
complexes.
Despite the low coordination number of the gold atom in 18,
there are no close contacts in the crystal, in accord with most
other triarylphosphine gold alkynyl complexes.32 The nearest
gold/gold distance (7.47 Å) is outside of the range associated
with aurophilic interactions, which normally require smaller
trialkylphosphine ligands to be observed in gold alkynyl
complexes.32 Interestingly, pairs of molecules pack in a head-
to-head manner, such that Ph3P ligands exhibit a sextuple phenyl
embrace.33 The corresponding phosphorus-phosphorus and
gold-gold distances are 7.47 and 11.56 Å, respectively.
As summarized in Table 1, the diplatinum complexes give
partially reversible oxidations that are presumed to generate
mixed valence radical cations.34 The oxidations of the buta-
diynediyl complexes 8 and 9 are thermodynamically more
favorable (less positive ∆E) and exhibit a larger degree of
reversibility (higher ic/a) than the hexatriynediyl complexes 12
and 17. Analogous chain length effects are observed with the
symmetrically substituted complexes (e.g., I vs III)2,3 and follow
logically from the HOMO energies.27 Complex 8, which can
be derived from II by replacing one electron-withdrawing
pentafluorophenyl ligand by an electron-releasing p-tolyl ligand,
is as expected more easily oxidized. Complex 12, which has
an analogous relationship to III, is also more easily oxidized.
However, as illustrated by IV and its higher homologues,3
p-tolyl ligands can have a deleterious affect upon reversibility.
It has been suggested that the pentafluorophenyl moiety may
in some way hinder a subsequent chemical reaction that involves
the aryl substituent.3 The platinum/gold complex 18 also gives
only irreversible oxidations, perhaps in part due to the decreased
steric shielding of the C4 chain.
3. Photophysical Data. The PtC4Pt′ and PtC4Au complexes
9 and 18 exhibit highly structured phosphorescence emissions
at 80 K in rigid MTHF glasses. The triplet states responsible
for these emissions are concentrated on the C4 units, as
evidenced by the dominant vibrational progression due to
the Ct C stretching mode. Nevertheless, several features
suggest that the triplet wave function is delocalized into the
platinum atom via π(C)-dπ(Pt) orbital overlap, but not to
any significant extent into the gold atom in 18. First, the
0-0 emission energy of 9 appears at a lower energy than
that of 18. This may be due to the influence of the two
platinum end-groups in 9 compared to only one in 18. Second,
the Huang-Rhys constant, which provides a relative measure
of the degree of excited state delocalization, is smaller for 9
compared to 18. This also suggests a greater degree of triplet
state delocalization in the diplatinum complex. It is further
significant that, in an earlier study, Che and co-workers
reported the phosphorescence of the digold complex
Cy3PAu(Ct C)2AuPCy3, which showed an emission with the
same 0-0 energy as 18.35 However, inspection of the spec-
trum of Cy3PAu(Ct C)2AuPCy3 suggests that the Huang-
Rhys constant is larger than that of 18, consistent with some
delocalization of the triplet wave function into the platinum
center in the latter complex.
We have also prepared an unsymmetrically substituted
octatetraynediyl complex by the displacement of one chloride
ligand in trans,trans-Cl(p-tol3P)2Pt(Ct C)4Pt(Pp-tol3)2Cl.5
However, it is difficult to avoid disubstitution in such
desymmetrizations, and we consider such strategies intrinsi-
cally less general. Numerous other symmetrically substituted
diplatinum butadiynediyl, hexatriynediyl, and ethynediyl
complexes have been synthesized.30 Tellingly, all butadiynediyl
and ethynediyl complexes prepared by Hagihara-type cou-
plings have been limited to tri(n-alkyl)phosphine-containing
end-groups.18 Hagihara couplings will also likely be limited
by the stabilities of the precursor polyynyl complexes
LyPt(Ct C)nH, which decrease dramatically as the sp chain
is lengthened.2,3 However, under carefully controlled condi-
tions, Hay homocouplings have been effected with tetradeca-
heptaynyl complexes (n ) 7).3
2. Structural and Electrochemical Data. Curiously, nearly
all symmetrically substituted diplatinum polyynediyl complexes
with C6 or longer chains crystallize with nearly coplanar end-
groups ((18.4°).2-6 Since DFT calculations do not indicate any
electronic conformational preference in the singlet ground
state,27 this is presumed to reflect a deep-seated crystal lattice
effect. Accordingly, the end-group/end-group angle in the
hexatriynediyl complex 17 is close to 0° (5.1-1.5°), exactly as
in the symmetrically substituted homologues with trans-(p-
tol)(Et3P)2Pt and trans-(p-tol)(p-tol3P)2Pt end-groups.6d How-
ever, analogously to the situation with biaryls Ar(Ct C)nAr (n
) 0-2),31 coplanar end-groups become impossible when the
Cx bridges are too short or the end-group substituents too large.
Thus, the end-group/end-group angle in the p-tol3P-substituted
butadiynediyl complex I (Figure 7) increases to 41.0-40.8°.
That in Et3P-substituted butadiynediyl complex 8 (Figure 1) is
62.3-60.1°. Curiously, that in the mixed p-tol3P/Et3P complex
9 (Figure 2) is lowest, 35.1-34.7°. The crystal structures of
two ethynediyl complexes, trans,trans-X(R3P)2PtCt CPt(PR3)2X
(X/R ) Cl/Ph, I/Me), are depicted in Figures 8 and 9.18b,30a
The end-group/end-group angles in these much more congested
systems increase to 82-90°, maximizing the separation of
phosphine ligands on opposite termini. In the Ph3P complex,
the C2 chain is completely shielded. This species was isolated
(29) Eastmond, R.; Johnson, T. R.; Walton, D. R. M. J. Organomet.
Chem. 1973, 50, 87.
(30) For additional Pt(Ct C)nPt complexes (n ) 1-3), see ref 18b
and (a) Su¨nkel, K.; Birk, U.; Robl, C. Organometallics 1994, 13, 1879. (b)
Klein, A.; Klinkhammer, K.-W.; Scheiring, T. J. Organomet. Chem. 1999,
592, 128. (c) Mu¨ller, C.; Lachicotte, R. J.; Jones, W. D. Organometallics
2002, 21, 1190. (d) Wong, W.-Y.; Wong, C.-K.; Lu, G.-L.; Cheah, K.-W.;
Shi, J.-X.; Lin, Z. J. Chem. Soc., Dalton Trans. 2002, 4587. (e) Yam, V. W.-
W.; Wong, K. M.-C.; Zhu, N. Angew. Chem., Int. Ed 2003, 42, 1400; Angew.
Chem. 2003, 115, 1438.
(31) (a) Brizius, G.; Billingsley, K.; Smith, M. D.; Bunz, U. H. F. Org.
Lett. 2003, 5, 3951. (b) Toyota, S.; Iida, T.; Kunizane, C.; Tanifuji, N.;
Yoshida, Y. Org. Biomol. Chem. 2003, 1, 2298. (c) Makino, T.; Toyota, S.
Bull. Chem. Soc. Jpn. 2005, 78, 917. (d) Toyota, S.; Yanagihara, T.; Yoshida,
Y.; Goichi, M. Bull. Chem. Soc. Jpn. 2005, 78, 1351. (e) Miljaniæ, O. S.;
Han, S.; Holmes, D.; Schaller, G. R.; Vollhardt, K. P. C. Chem. Commun.
2005, 2606. (f) Nandy, R.; Subramoni, M.; Varghese, B.; Sankararaman,
S. J. Org. Chem. 2007, 72, 938.
(32) Liau, R.-Y.; Schier, A.; Schmidbaur, H. Organometallics 2003, 22,
3199.
(33) (a) Scudder, M.; Dance, I. Chem.-Eur. J. 2002, 8, 5456. (b) Dance,
I.; Scudder, M. New J. Chem. 1998, 481.
(34) For other mixed valence diplatinum radical cations, see: Klein, A.;
Kaim, W. Organometallics 1995, 14, 1176.

Unsymmetrically Substituted Butadiynediyl and Hexatriynediyl Complexes
Organometallics, Vol. 27, No. 19, 2008 4989
of conformational isomerism due to the effective cylindrical
symmetry of the gold end-group.
4. Conclusion
This study has established methodology for accessing un-
symmetrically substituted butadiynediyl and hexatriynediyl
complexes containing one and two platinum end-groups.
Although some limitations due to steric and electronic effects
are evident, successful extensions to higher homologues can
be anticipated, up to the point where the Pt(Ct C)nH coupling
partners become too unstable. It also probable that the very
stable platinum/gold complex 18, and analogues thereof, will
constitute useful building blocks for preparing species with
longer sp carbon chains. With the butadiynediyl complexes, both
structural and low-temperature phosphorescence data underscore
the important influence that end-group/end-group interactions
can have upon molecular properties at short Cx chain lengths.
Efforts are currently underway to exploit such interactions to
generate new classes of atropisomers.37
Figure 10. (a) Eclipsed (9-ec) and staggered (9-st) conformations
of the triplet excited state of diplatinum complex 9. (b) Schematic
of interactions between the symmetric combination of dyz orbitals
on the platinum atoms and the symmetric πy* orbital of the C4
chain in 9-ec.
Experimental Section
As noted above, the emission of 9 in the frozen solvent glass
features two distinct 0-0 bands and corresponding vibrational
progressions, suggesting the presence of sample (or site)
heterogeneity in the glass. The heterogeneity disappears above
the solvent glass-to-fluid transition. This behavior is not
observed with 18, suggesting that two platinum end-groups are
necessary for heterogeneity. In previous studies, we and others
have used density functional calculations to explore the nature
of the dπ(Pt)-pπ(C) interactions in platinum polyynyl and
diplatinum polyynediyl complexes.27,36 The data clearly indicate
that the relative orientation of the square-planar end-group
relative to the π-electron system of the Cx chain affects the
energy of the relaxed triplet excited state.
1. General Procedures. General procedures, chemical sources
and purifications, instrumentation, and protocols for the photo-
physical studies were identical with those in three previous
papers.6b,c,9 The one chemical new to this study outside of those
with literature citations below (KN(SiMe3)2, Fluka; 0.5 M in
toluene) was used as received.
trans,trans-(C6F5)(Et3P)2Pt(Ct C)2Pt(PEt3)2(p-tol) (8). A Schlenk
flask was charged with trans-(C6F5)(Et3P)2Pt(Ct C)2H (6;7 0.058
g, 0.090 mmol), trans-(p-tol)(Et3P)2PtCl (7;7 0.050 g, 0.090 mmol),
CuCl (0.0020 g, 0.020 mmol), and HNEt2 (6 mL) with stirring.
After 120 h, the solvent was removed by oil pump vacuum. The
residue was chromatographed (two successive silica gel columns:
20 × 1 cm, 60:40 v/v hexanes/CH2Cl2; 15 × 1 cm, 50:50 v/v
hexanes/toluene). The solvent was removed from the product-
containing fractions by oil pump vacuum. The yellow residue was
washed with ethanol (1 mL) to give 8 as an off-white powder (0.065
g, 0.056 mmol; 62%), mp 112 °C. Anal. Calcd for C41H67F5P4Pt2:
C, 42.12; H, 5.78. Found: C, 41.76; H, 5.74. DSC:34 endotherm
with Ti, 84.8 °C; Te, 110.5 °C; Tc, 113.3 °C; Tf, 138.9 °C. TGA:
weight loss 58%, 220-414 °C. NMR (δ, CDCl3): 1H 7.13 (d, 2H,
3JHH ) 7.7 Hz, 3JHPt ) 38 Hz,39 o to Pt), 6.75 (d, 2H, 3JHH ) 7.7
Hz, m to Pt), 2.17 (s, 3H, CH3 p to Pt), 1.79-1.73 (m, 12H, PCH2),
1.72-1.69 (m, 12H, P′CH2), 1.07-0.99 (m, 36H, PCH2CH3/
P′CH2CH3); 13C{1H}40 151.2 (s, i to Pt), 138.8 (s, o to Pt), 129.9
We suggest that the spectroscopic heterogeneity observed for
triplet 9 in the low-temperature glass arises from nonintercon-
verting conformers with roughly eclipsed and staggered geom-
etries (9-ec and 9-st, Figure 10a). The latter represents an excited
state analogue of the sterically mandated conformations of the
ethynediyl complexes in Figures 8 and 9. The heterogeneity
disappears above the solvent glass-to-fluid transition due to
relaxation to the lower energy conformation. Note that the end-
group/end-group angle in crystalline singlet 9 (35.1-34.7°) is
closer to that of 9-ec.
The spectroscopic heterogeneity would be rationalized by
different degrees of triplet excited state delocalization in 9-ec
and 9-st. That in the former should be greater due to the
uninterrupted conjugation between both platinum atoms and the
π-system of the C4 chain. For example, as shown in Figure 10b,
an unfilled πy* level of the C4 chain can interact with the filled
dxy levels on each platinum center, leading to two filled MOs
that are delocalized across the entire PtC4Pt system. A similar,
fully delocalized array cannot exist in 9-st since the dπ orbital
systems on the two platinum end-groups are orthogonal. This
is furthermore consistent with the absence of spectroscopic
heterogeneity with the PtC4Au complex 18, which is incapable
3
(s, p to Pt), 128.1 (s, JCPt ) 23.5 Hz,39 m to Pt), 97.8 (s, PtCt ),
97.4 (s, PtCt C), 95.5 (s, PtCt C), 29.7 (s, CH3 p to Pt), 15.6
(virtual t, JCP ) 17.4 Hz,41 PCH2), 15.1 (virtual t, JCP ) 17.2
Hz,41 P′CH2), 8.0 (s, PCH2CH3), 7.8 (s, P′CH2CH3); 31P{1H} 13.1
(s, 1JPPt ) 2459 Hz, PC6F5),39 10.3 (s, 1JPPt ) 2649 Hz, Pp-tol).39 IR
(cm-1, powder film): νC≡C not observed. UV-vis (CH2Cl2, 1.25
× 10-5 M):42 318 (16700), 338 (18700). MS:43 1168 (M+, 100%),
1077 ([M - tol)]+, 10%), 765 ([M - C6F5 - 2PEt3]+, 50%), 597
([(C6F5)(Et3P)2Pt]+, 20%), 522 ([(tol)(Et3P)2Pt]+, 100%).
1
1
(38) DSC and TGA data were treated as recommended by: Cammenga,
H. K.; Epple, M. Angew. Chem., Int. Ed. Engl. 1995, 34, 1171; Angew.
Chem. 1995, 107, 1284. The Te values best represent the temperature of
the phase transition or exotherm.
(35) Che, C.-M.; Chao, H.-Y.; Miskowski, V. M.; Li, Y.; Cheung, K.-
K. J. Am. Chem. Soc. 2001, 123, 4985.
(39) This coupling represents a satellite (d; 195Pt ) 33.8%) and is not
reflected in the peak multiplicity given.
(36) (a) Glusac, K.; Kose, M. E.; Jiang, H.; Schanze, K. S. J. Phys.
Chem. B 2007, 111, 929. (b) Cooper, T. M.; Blaudeau, J.-P.; Hall, B. C.;
Rogers, J. E.; McLean, D. G.; Liu, Y.; Toscano, J. P. Chem. Phys. Lett.
2004, 400, 239.
(40) Unless otherwise noted, one PtC and the C6F5 13C NMR signals
were not observed. The PtCxPt signals were assigned according to chemical
shift and coupling constant trends established for closely related species.2,3,6d,7
n
(41) Hersh, W. H. J. Chem. Educ. 1997, 74, 1485; the JCP values
represent the apparent couplings between adjacent peaks of the triplet.
(37) Dey, S. Work in progress, Texas A&M University.

4990 Organometallics, Vol. 27, No. 19, 2008
de Quadras et al.
trans,trans-(C6F5)(Et3P)2Pt(Ct C)2Pt(Pp-tol3)2(p-tol) (9). A
Schlenk flask was charged with 6 (0.162 g, 0.250 mmol), trans-
(p-tol)(p-tol3P)2PtCl (4;3 0.233 g, 0.250 mmol), t-BuOK (0.0338
g, 0.301 mmol), KPF6 (0.0561 g, 0.304 mmol), CuCl (0.0049 g,
0.049 mmol), THF (10 mL), and methanol (10 mL) with stirring.
After 96 h, the solvent was removed by oil pump vacuum. The
residue was extracted with CH2Cl2. The extract was filtered through
a short alumina/Celite pad. The solvent was removed by rotary
evaporation and oil pump vacuum to give 9 as a pale yellow solid
(0.350 g, 0.228 mmol; 91%), dec pt > 167 °C (gradual darkening,
then melting). Anal. Calcd for C71H79F5P4Pt2: C, 55.32; H, 5.17.
Found: C, 55.33; H, 5.17. DSC:38 endotherm with Ti, 105.3 °C;
Te, 108.9 °C; Tc, 122.0 °C; Tf, 122.2 °C; exotherm with Ti 122.2
°C; Te, 122.2 °C; Tc, 132.0 °C; Tf, 132.1 °C; endotherm with Ti,
132.2 °C; Te, 132.2 °C; Tc, 143.5 °C; Tf, 144.5 °C; endotherm with
Ti, 163.8 °C; Te, 179.6 °C; Tc, 187.6 °C; Tf, 191.2 °C. TGA: weight
loss 36%, 195-403 °C. NMR (δ, CDCl3): 1H 7.43-7.39 (m, 12H,
177.8 °C. TGA: weight loss 26%, 236-410 °C. NMR (δ, CDCl3):
1H 7.50-7.47 (m, 12H, o to P), 7.28-7.24 (m, 12H, o to P′), 7.06
3
3
(d, 12H, JHH ) 7.2 Hz, m to P), 6.95 (d, 12H, JHH ) 7.2 Hz, m
3
3
to P′), 6.27 (d, JHH ) 2H, 7.3 Hz, o to Pt), 6.02 (d, JHH ) 7.1
Hz, 2H, m to Pt), 2.32 (s, 18H, CH3 p to P), 2.22 (s, 18H, CH3 p
to P′), 1.93 (s, 3H, CH3 p to Pt); 13C{1H}40 150.3 (t, JCP ) 9.9
2
1
Hz, i to Pt), 145.7 (dm, JCF ) 254.0 Hz, o-C6F5), 140.8 (s, p to
P), 140.3 (s, p to P′), 139.1 (s, o to Pt), 134.6 (virtual t, 2JCP ) 6.1
Hz,41 o to P), 134.4 (virtual t, JCP ) 6.3 Hz,41 o to P′), 129.0 (s,
2
p to Pt), 128.4 (virtual t, JCP ) 5.3 Hz,41 m to P), 128.2 (virtual
3
t, 3JCP ) 5.3 Hz,41 m to P′), 127.7 (virtual t, 1JCP ) 29.9 Hz,41 i to
2
P; i to P′ obscured), 127.5 (s, m to Pt), 109.9 (t, JCP ) 15.2 Hz,
p-tolPtCt ), 99.2 (s, PtCt C), 98.4 (s, PtC≡C), 93.5 (br s,
C6F5PtCt ), 61.3 (s, PtCt CC), 60.2 (s, PtCt CC), 21.29 (s, CH3 p
to P), 21.27 (s, CH3 p to P′), 20.5 (s, CH3 p to Pt); 31P{1H} 18.7
(s, 1JPPt ) 2955 Hz, Pp-tol),39 17.2 (s, 1JPPt ) 2689 Hz, PC6F5).39 IR
(cm-1, powder film): νCt 2104 (m). UV-vis (CH2Cl2, 1.25 ×
C
o to P), 6.98 (d, 12H, 3JHH ) 7.7 Hz, m to P), 6.29 (d, 2H, 3JHH
)
10-5 M):42 329 (32 100), 348 (14 800), 376 (8400). MS:43 1937
(M+, 10%), 970 ([(C6F5)(tol3P)2Pt]+, 20%), 894 ([(tol)(tol3P)2Pt]+,
30%), 803 ([(tol3P)2Pt]+, 100%).
3
7.7 Hz, o to Pt), 5.98 (d, 2H, JHH ) 7.5 Hz, m to Pt), 2.29 (s,
18H, CH3 p to P), 1.90 (s, 3H, CH3 p to Pt), 1.54-1.51 (m, 12H,
PCH2), 0.95-0.89 (m, 18H, PCH2CH3); 13C{1H}40 152.2 (s, i to
Pt), 139.2 (s, o to Pt), 139.1 (s, p to P), 134.6 (s, o to P), 128.9
(virtual t, 1JCP ) 29.0 Hz,41 i to P), 128.6 (s, p to Pt), 128.0 (s, m
to P), 127.4 (s, m to Pt), 103.1 (s, PtCt ), 99.4 (s, PtCt C), 96.0 (s,
PtCt C), 21.4 (s, CH3 p to P), 20.5 (s, CH3 p to Pt), 15.5 (virtual
trans,trans-(C6F5)(Et3P)2Pt(Ct C)3Pt(PEt3)2(p-tol) (17). A round-
bottom flask was charged with 7 (0.113 g, 0.203 mmol), KPF6
(0.041 g, 0.22 mmol), t-BuOK (0.0270 g, 0.243 mmol), CuCl
(0.0040 g, 0.0040 mmol), THF (10 mL), and methanol (10 mL). A
Schlenk flask was charged with trans-(C6F5)(Et3P)2Pt(Ct C)3SiEt3
(15;7 0.154 g, 0.203 mmol) and CH2Cl2 (4 mL), and n-Bu4N+F-
(0.023 mL, 1.0 M in THF, 5 wt % H2O) was added with stirring.
After 15 min, the solution derived from 7 was transferred via syringe
to that derived from 15. The mixture was stirred overnight. The
precipitate was isolated by filtration, washed with ethanol, and dried
by oil pump vacuum to give 17 as a yellow solid (0.142 g, 0.120
mmol; 59%), dec pt > 211 °C (gradual darkening without melting).
Anal. Calcd for C43H67F5P4Pt2: C, 43.29; H, 5.66. Found: C, 42.26;
H, 5.66. DSC: no features below 200 °C. TGA: weight loss 47%,
235-410 °C. NMR (δ, CDCl3): 1H 7.11 (d, 2H, 3JHH ) 7.5 Hz, o
to Pt), 6.78 (d, 2H, 3JHH ) 7.5 Hz, m to Pt), 2.17 (s, 3H, CH3 p to
Pt), 1.78-1.67 (m, 24H, PCH2CH3 + P′CH2CH3), 1.10-1.02 (m,
36H, PCH2CH3 + P’CH2CH3); 13C{1H}40 150.3 (s, i to Pt), 138.9
(s, o to Pt), 130.6 (s, p to Pt), 128.6 (s, m to Pt), 109.2 (s, PtCt ),
93.3 (s, PtCt C), 93.1 (s, PtCt C), 60.8 (s, PtCt CC), 60.7 (s,
PtCt CC), 20.9 (s, CH3 p to Pt), 15.9 (virtual t, 1JPC ) 17.5 Hz,41
PCH2), 15.3 (virtual t, 2JPC ) 17.3 Hz,41 P′CH2), 8.1 (s, PCH2CH3),
1
t, JCP ) 17.5 Hz,41 PCH2), 7.8 (s, PCH2CH3); 31P{1H} 18.3 (s,
1
1JPPt ) 2987 Hz, Pp-tol3),39 12.9 (s, JPPt ) 2461 Hz, PEt3).39 IR
(cm-1, powder film), νCt C 2148 (w), 2001 (w); UV-vis (CH2Cl2,
1.25 × 10-5 M; MTHF, see Table 5 and Figure 5),42 300 (15 400),
324 (13800), 349 (13 300). MS:43 1541 (M+, 90%), 1449 ([M -
tol]+, 30%), 1358 ([M - C6F5]+, 3%), 950 ([M - C6F5 - PEt3 -
Ptol3]+, 100%).
trans,trans-(C6F5)(p-tol3P)2Pt(Ct C)3Pt(Pp-tol3)2(p-tol) (12).
A. A Schlenk flask was charged with 4 (0.0484 g, 0.0520 mmol),
HNEt2 (20 mL), and CuCl (0.0040 g, 0.040 mmol) with stirring
and cooled to -45 °C. Another Schlenk flask was charged with
trans-(C6F5)(p-tol3P)2Pt(Ct C)3SiEt3 (13,3 0.0600 g, 0.0520 mmol)
and CH2Cl2 (2 mL), and n-Bu4N+F- (0.016 mL, 1.0 M in THF, 5
wt % H2O) was added with stirring. After 15 min, the solution
derived from 13 was added via syringe to that of 4. The mixture
was allowed to warm at room temperature overnight. After 6 days,
the solvent was removed by oil pump vacuum. The residue was
extracted with hexanes (3 × 5 mL) and toluene (3 × 7 mL). The
extracts were passed in sequence through an alumina column (4 ×
1 cm), which was rinsed with toluene. The solvent was removed
from the toluene fractions by oil pump vacuum to give a mixture
of 12 and 13 (0.092 g) The solid was dissolved in CH2Cl2 and
layered with methanol. A yellow powder precipitated overnight,
which was collected by filtration and dried by oil pump vacuum to
give 12 as a yellow solid (0.0390 g, 0.0208 mmol; 40%).
B. A round-bottom flask was charged with 4 (0.0697 g, 0.0752
mmol), KPF6 (0.0152 g, 0.0825 mmol), t-BuOK (0.0092 g, 0.082
mmol), CuCl (0.0020 g, 0.0020 mmol), THF (10 mL), and methanol
(10 mL). A Schlenk flask was charged with 13 (0.087 g, 0.0751
mmol) and CH2Cl2 (4 mL), and n-Bu4N+F- (0.023 mL, 1.0 M in
THF, 5 wt % H2O) was added with stirring. After 15 min, the
solution derived from 4 was transferred via syringe to that derived
from 13. The mixture was stirred overnight. The precipitate was
isolated by filtration, washed with ethanol, and dried by oil pump
vacuum to give 12 as a yellow solid (0.0910 g, 0.0470 mmol; 63%),
dec pt > 221° (gradual darkening, then melting). Anal. Calcd for
1
8.0 (s, P′CH2CH3); 31P{1H} 13.1 (s, JPPt ) 2406 Hz, PC6F5),39
1
11.3 (s, JPPt ) 2620 Hz, Pp-tol).39 IR (cm-1, powder film): νCt
C
2150 (ms), 2096 (vw), 2003 (w). UV-vis (CH2Cl2, 1.25 × 10-5
M):42 281 (53 600), 299 (34 900), 312 (39 600), 342 (9500), 367
(5400). MS:43 1192 (M+, 100%), 597 ([(C6F5)(Et3P)2Pt]+, 20%),
522 ([(tol)(Et3P)2Pt]+, 60%).
trans-(C6F5)(Et3P)2Pt(Ct C)2Au(PPh3) (18). A Schlenk flask
was charged with 6 (0.100 g, 0.154 mmol), (Ph3P)AuCl (0.076 g,
0.154 mmol),21 and THF (5 mL) with stirring. Then KN(SiMe3)2
(0.610 mL, 0.5 M in toluene, 0.305 mmol) was added. After 18 h,
the volatiles were removed by oil pump vacuum. The residue was
extracted with CH2Cl2 (2 × 2 mL). The extract was filtered through
an alumina/Celite pad (2 × 1 cm). The solvent was removed by
rotary evaporation and oil pump vacuum to give 18 as a yellow
powder (0.166 g, 0.148 mol; 97%), dec pt > 190 °C (gradual
darkening, then melting). Anal. Calcd for C40H45AuF5P3Pt: C, 43.45;
H 4.10. Found: C, 43.76; H, 4.72. DSC:38 endotherm with Ti, 104.0
°C; Te, 107.6 °C; Tc, 120.6 °C; Tf, 123.3 °C; endotherm with Ti,
131.4 °C; Te, 137.0 °C; Tc, 148.4 °C; Tf, 155.5 °C; endotherm with
Ti, 185.2 °C; Te, 191.1 °C; Tc, 202.9 °C; Tf, 205.6 °C. TGA: weight
loss 38%, 206-404 °C. NMR (δ, CDCl3): 1H 7.48-7.37 (m, 15H,
Ph), 1.73-1.71 (m, 12H, PCH2), 1.04-0.96 (m, 18H, PCH2CH3);
C
103H91F5P4Pt2: C, 63.83; H, 4.73. Found: C, 63.03; H, 4.73. DSC:38
endotherm with Ti, 91.6 °C; Te, 110.8 °C; Tc, 132.3 °C; Tf, 138.1
°C; endotherm with Ti, 140.2 °C; Te, 158.2 °C; Tc, 174.8 °C; Tf,
13C{1H}40 146.8 (dm, 1JCF ) 197 Hz, o-C6F5), 136.5 (dm, 1JCF
)
(42) Absorptions are in nm (ε, M-1 cm-1).
(43) FAB, 3-NBA: m/z for the most intense peak of the isotope envelope;
relative intensities (%) are for the specified mass range.
197 Hz, m-C6F5), 134.2 (d, 2JCP ) 13.8 Hz, o to P), 131.4 (br s, p
to P), 129.8 (d, 1JCP ) 55.6 Hz, i to P), 129.0 (d, 3JCP ) 11.2 Hz,

Unsymmetrically Substituted Butadiynediyl and Hexatriynediyl Complexes
Organometallics, Vol. 27, No. 19, 2008 4991
2
m to P), 116.6 (d, JCP ) 143.7 Hz, AuCt ), 93.7 (s, PtCt ), 91.9
9 · CH2Cl2, 30 543; 17, 10 768; 18 · (C7H8)0.5, 11 502. Lorentz,
polarization, and absorption corrections were applied.44 The space
groups were determined from systematic absences and subsequent
least-squares refinement. The structures were solved by direct
methods. The parameters were refined with all data by full-matrix-
least-squares on F2 using SHELXL-97.45 Non-hydrogen atoms were
refined with anisotropic thermal parameters. The hydrogen atoms
were fixed in idealized positions using a riding model. Scattering
factors were taken from the literature.46
3
(d, JCP ) 30.2 Hz, AuCt C), 90.6 (s, PtCt C), 15.5 (virtual t,
1JCP ) 17.5 Hz,41 PCH2), 7.8 (s, PCH2CH3); 31P{1H} 42.5 (s, PPh3),
13.6 (s, JPPt ) 2422 Hz, PEt3).39 IR (cm-1, powder film): νCt
1
C
2146 (m), 2092 (w). UV-vis (CH2Cl2, 1.25 × 10-5 M; MTHF,
see Table 5 and Figure 5):42 301 (56000), 358 (7200). MS:43 1565
([M + AuPPh3]+, 100%), 1106 (M+, 80%).
trans-(C6F5)(Et3P)2Pt(Ct C)2W(CO)3(η5-C5H5) (22). A Schlenk
flask was charged with trans-(C6F5)(Et3P)2PtCl (2;2 0.234 g, 0.369
mmol), CuI (0.0070 g, 0.036 mmol), and HNEt2 (20 mL) with
stirring, and cooled to 0 °C. Then a solution of (η5-C5H5)(CO)3-
W(Ct C)2H (23;25 0.181 g, 0.472 mmol) in CH2Cl2 (5 mL) was
added. The cold bath was allowed to warm to room temperature.
After 20 h, the solvent was removed by oil pump vacuum. The tan
residue was extracted with toluene (3 × 3 mL). The extracts were
filtered through an alumina column (5 × 2 cm), which was rinsed
with toluene. The solvent was removed by rotary evaporation. The
residue was washed with ethanol (5 mL) and dried by oil pump
vacuum to give 22 as a yellow solid (0.290 g, 0.295 mmol, 80%)
The structure of 8 was disordered over two positions with a nearly
perfect overlay of the C6F5 and the p-tolyl ligands. The occupancy
refined to 73:27. However, the p-methyl and p-fluorine substituents
could not be refined separately (F14/C14a; F84/C84a). Some of
the PCH2 carbon atoms of 9 · CH2Cl2 were also disordered and
refined to occupancy ratios of 61:39 (C101/C111, C105/C115) and
44:56 (C104/C114). The toluene molecule in 18 · (C7H8)0.5 was
disordered and refined to 50% occupancy.
of 80% purity by 31P NMR. NMR (δ, CDCl3): H 5.59 (s, 5H,
1
Acknowledgment. We thank the U.S. National Science
Foundation (J.A.G., CHE-0719267; K.S.S., CHE-0515066),
the Deutsche Forschungsgemeinschaft (SFB 583), and Johnson
Matthey (platinum loans) for support.
C5H5), 1.77-1.68 (m, 12H, PCH2), 1.06-0.98 (m, 18H, PCH2CH3);
13C{1H}40 211.0 (s, CO), 116.4 (s, WCt ), 93.9 (s, PtCt ), 91.6
(s, C5H5), 68.1, 54.6 (2 s, WCt C–C, tentative), 15.5 (virtual t,
1JCP ) 17.5 Hz,41 PCH2), 7.8 (virtual t, JCP ) 11.6 Hz,41
2
PCH2CH3); 31P{1H} 12.8 (s, 80%, 1JPPt ) 2431 Hz),39 9.8 (s, 16%
Supporting Information Available: CIF files with crystal-
lographic data for 8, 9, 17, and 18. This material is available free
of charge via the Internet at htpp://pubs.acs.org.
(major byproduct), JPPt ) 2427 Hz).39 IR (cm-1, powder film):
1
νCt 2146 (w), 2084 (w), νCO 2034 (s), 1938 (s).
C
Crystallography. A CH2Cl2 solution of 8 was layered with
methanol and refrigerated. After 1 week, white prisms of 8 were
isolated. CH2Cl2 solutions of 9 and 17 were layered with hexanes.
After 2 weeks, white prisms of 9 · CH2Cl2 and yellow prisms of 17
were isolated. A toluene solution of 18 was layered with ethanol.
After 1 week, pale yellow plates of 18 · (C7H8)0.5 were isolated.
Data were collected using a Nonius KappaCCD detector as outlined
in Table 3.
OM800493X
(44) (a) Collect data collection software; Nonius B.V., 1998. (b)
Scalepack data processing software: Otwinowski, Z.; Minor, W. in Methods
Enzymol. 1997, 276, 307.
(45) Sheldrick, G. M. SHELX-97, Program for refinement of crystal
structures; University of Go¨ttingen, 1997.
(46) Cromer, D. T.; Waber, J. T. In International Tables for X-ray
Crystallography; Ibers, J. A., Hamilton, W. C., Eds.; Kynoch: Birmingham,
England, 1974.
Cell parameters were obtained from 10 frames using a 10° scan
and were refined with the following number of reflections: 8, 4658;