C-metalated diazoalkane complexes of platinum based on PCP- And PCN-type ligands

Article abstract of DOI:10.1021/om050637x

A series of the first C-metalated diazoalkane complexes of Pt, based on pincer-type PCN and PCP ligands (PCP = C₆)H₃[CH ₂P(iPr)₂]₂) PCN = C₂H ₃[CH₂P(tBu)₂](CH₂) ₂N(CH₃)₂), with the general formula (PCX)Pt[C(N₂)R] (2, X = N, R = Ph; 3, X = N, R = SiMe₃; 5, X = P, R = Ph) were prepared via direct nucleophilic attack of RCN ₂^-Li⁺ at the metal center. These remarkably stable complexes were characterized by ¹H, ³¹P{ ¹H}, and ¹³C NMR and IR spectroscopy. Complex 2 was also characterized by single-crystal X-ray crystallography. Reactions of the C-metalated diazoalkane Pt complexes with Cu(I) (reported to catalyze decomposition of diazoalkanes) were strongly influenced by the nature of the pincer ligand. Bimolecular coupling to generate diphenylacetylene and (PCP)Pt-OTf (6) was observed in the case of the rigid PCP-based complex 5, while the hemilabile PCN-based complex 2 was converted to an ylide-bridged dimeric structure, the formation of which was promoted by the decoordination of the ligand amine arm. In addition, formation of the stable metalsubstituted azine-type binuclear complex 10, generated by reaction of 2 with Rh ₂(OAc)₄, is described.

Full text of DOI:10.1021/om050637x

Organometallics 2005, 24, 5937-5944
5937
C-Metalated Diazoalkane Complexes of Platinum Based
on PCP- and PCN-Type Ligands
Elena Poverenov,† Gregory Leitus,‡ Linda J. W. Shimon,‡ and David Milstein*,†
Department of Organic Chemistry and Unit of Chemical Research Support,
The Weizmann Institute of Science, Rehovot 76100, Israel
Received July 27, 2005
A series of the first C-metalated diazoalkane complexes of Pt, based on pincer-type PCN
and PCP ligands (PCP ) C6H3[CH2P(iPr)2]2; PCN ) C6H3[CH2P(tBu)2](CH2)2N(CH3)2), with
the general formula (PCX)Pt[C(N2)R] (2, X ) N, R ) Ph; 3, X ) N, R ) SiMe3; 5, X ) P, R
-
) Ph) were prepared via direct nucleophilic attack of RCN2 Li+ at the metal center. These
1
remarkably stable complexes were characterized by H, 31P{1H}, and 13C NMR and IR
spectroscopy. Complex 2 was also characterized by single-crystal X-ray crystallography.
Reactions of the C-metalated diazoalkane Pt complexes with Cu(I) (reported to catalyze
decomposition of diazoalkanes) were strongly influenced by the nature of the pincer ligand.
Bimolecular coupling to generate diphenylacetylene and (PCP)Pt-OTf (6) was observed in
the case of the rigid PCP-based complex 5, while the hemilabile PCN-based complex 2 was
converted to an ylide-bridged dimeric structure, the formation of which was promoted by
the decoordination of the ligand amine arm. In addition, formation of the stable metal-
substituted azine-type binuclear complex 10, generated by reaction of 2 with Rh2(OAc)4, is
described.
Introduction
metalated diazoalkanes is the potential for controlled
release of N2 to give reactive carbenoid species. Since
carbene reactivity is strongly influenced by the nature
of the LnM fragment,4 R-metalation of diazoalkanes can
allow tuning of their reactivity by variations in the
metals and ligands. In addition, C-metalated diazo
complexes may provide new pathways for the synthesis
of organic and organometallic compounds. To the best
of our knowledge, the relatively few reported C-meta-
lated diazoalkane complexes include complexes of the
metals Rh,5 Pd,6 Ni,7 and Os.8
Bulky bis-chelating tridentate pincer-type ligands are
effective in the stabilization of reactive species.9 Using
phosphine-based pincer-type ligands, stable complexes
of carbene,10 quinone methide,11 phenoxonium,12 xy-
lylene,13 metallaquinone,14 and methylene arenium15
Reactions of organometallic complexes with diazoal-
kanes have attracted much attention, since diazoal-
kanes are useful substrates in the synthesis of carbene
complexes, formed as a result of N2 loss,1 and in the
generation of metal carbene intermediates in catalytic
cyclopropanation and C-H activation reactions.2 How-
ever, the diazo unit could also remain coordinated to
the metal center, resulting in N- or C-bonded diazoal-
kane complexes. While a growing number of N-coordi-
nated organometallic complexes have been reported and
studied in connection with dinitrogen activation,3 only
few examples of C-coordinated complexes have been
described. One of the reasons for the interest in C-
* To whom correspondence should be addressed. E-mail:
david.milstein@weizmann.ac.il. Fax: 972-8-9344142.
† Department of Organic Chemistry.
(4) (a) Carter, E. A.; Goddard, W. A. J. Am. Chem. Soc. 1986, 108,
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Y.; Simard, M.; Beauchamp, A. L.; Brewer, J. C.; Gray, H. B.
Organometallics 1996, 15, 1166. (b) Menu, M. J.; Desrosiers, P.;
Dartiguenave, M.; Dartiguenave, Y.; Bertrand, G. Organometallics
1987, 6, 1822.
‡ Unit of Chemical Research Support.
(1) (a) Che, C. M.; Huang, J. S. Coord. Chem. Rev. 2002, 231, 151.
(b) Cohen, R.; Rybtchinski, B.; Gandelman, M.; Rozenberg, H.; Martin,
J. M. L.; Milstein, D. J. Am. Chem. Soc. 2003, 125, 6532. (c) Schwab,
P.; France, M. B.; Ziller, J. W.; Grubbs, R. H. Angew. Chem., Int. Ed.
Engl. 1995, 34, 2039. (d) Davies, H. M. L.; Autoulinakis, E. G. J.
Organomet. Chem. 2001, 47.
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F.; Cenini, S. Eur. J. Inorg. Chem. 2003, 7, 1452. (c) Marko, I. E.;
Kumamoto, T.; Giard, T. Adv. Synth. Catal. 2002, 344, 1063. (d) Lin,
Y.-L.; Turos, E. J. Organomet. Chem. 2001, 630, 57.
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(9) For recent reviews on pincer-type complexes, see: (a) Albrecht,
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Boom, M. E.; Milstein, D. Chem. Rev. 2003, 103, 1759. (c) Jensen, C.
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10.1021/om050637x CCC: $30.25 © 2005 American Chemical Society
Publication on Web 10/22/2005

5938 Organometallics, Vol. 24, No. 24, 2005
Poverenov et al.
Scheme 1
have been synthesized. In addition, pincer-type ligands
have been utilized in the stabilization of highly unsat-
urated cationic complexes.16 With an interest in the
generation of C-metalated diazo complexes with control-
lable properties, we have decided to utilize pincer-type
ligands.
Figure 1. ORTEP view of a molecule of complex 2 at the
50% probability level. Hydrogen atoms are omitted for
clarity.
Table 1. Selected Bond Lengths (Å) and Angles
(deg) of Complex 2
In this paper we report the synthesis of the first
C-metalated diazo complexes of Pt. These complexes are
based on hemilabile PCN and rigid PCP pincer-type
systems. It is demonstrated that the reactivity of
C-metalated diazoalkane complexes is strongly depend-
ent on the pincer-ligand properties. In addition, forma-
tion of a metal-substituted azine compound is described.
Bond Lengths
Pt(1)-C(1)
Pt(1)-N(3)
Pt(1)-P(4)
Pt(1)-C(11)
2.147(7)
2.177(6)
2.220(18)
2.053(7)
C(1)-C(2)
N(1)-C(1)
N(1)-N(2)
C(2)-C(7)
1.469(11)
1.297(10)
1.144(10)
1.398(10)
Bond Angles
C(1)-Pt(1)-N(3)
C(1)-Pt(1)-P(4)
C(11)-Pt(1)-N(3)
C(11)-Pt(1)-P(4)
88.5(3)
96.8(2)
93.2(3)
83.6(2)
C(1)-N(1)-N(2)
N(1)-C(1)-C(2)
N(1)-C(1)-Pt(1)
C(2)-C(1)-Pt(1)
176.3(8)
112.7(7)
123.5(6)
122.8(5)
Results and Discussion
Formation of C-Metalated Diazo Complexes
Based on a Hemilabile PCN Ligand. The recently
reported17 complex 1, based on the “long N-arm” hemi-
labile PCN ligand, was reacted with the in situ prepared
lithiated diazo compound PhCN2-Li+ in THF at -30 °C
(Scheme 1). After 30 min the reaction mixture was
warmed to room temperature, resulting in a red solution
of (PCN)Pt[C(N2)Ph] (2). The pure complex 2 was fully
slightly distorted square planar structure. The Pt-C1
bond length of 2.147 Å is slightly shorter than other
reported Pt-C bond distances trans to aryl groups,
which are usually close to 2.20 Å (2.187 Å for C6H3-
17
[CH2P(tBu)2][CH2CH2N(Me)2]PtCH3 or 2.186 Å for
C6H3[CH2P(Ph)2]2PtCF2CF2CF318). This might have a
contribution to the high stability of complex 2.
The diazo CN2 unit is almost linear (176.3°), and C-N
(1.30 Å) and N-N (1.14 Å) bond lengths are similar to
those usually observed for C-metalated diazoalkanes.
However, in comparison with the corresponding bond
lengths of the Pd(II) and Rh(I) complexes PdCl(N2CCO2-
Et)(PPh3)2 (C-N ) 1.27 Å, N-N ) 1.17 Å)6a and Rh-
(N2CSiMe3)(PEt3)3 (C-N )1.28 Å, N-N ) 1.18 Å),5a it
is noteworthy that complex 2 has a higher contribution
of “C-N(single bond)-N-N(triple bond)” (structure B)
than other C-metalated d8 complexes.
1
characterized by 31P, H, and 13C NMR and IR spec-
troscopy. In 31P{1H} NMR it gives rise to a singlet at
63.11 ppm with Pt satellites (JPt-P ) 4025 Hz), and in
the 13C{1H} NMR spectrum the Pt[C(N2)Ph] carbon
appears as a singlet at 157.92 ppm and the ipso carbon
exhibits a doublet at 149.99 ppm (JP-C ) 1 Hz). In the
IR spectrum the diazo unit gives rise to absorption at
1962 cm-1
.
Yellow plates of complex 2 suitable for a single-crystal
X-ray analysis were obtained by crystallization of 2 from
a benzene/pentane solution at room temperature (Figure
1). Selected bond lengths and bond angles are given in
Table 1. According to the X-ray data, complex 2 has a
(10) (a) Gandelman, M.; Rybtchinski, B.; Ashkenazi, N.; Gauvin, R.
M.; Milstein, D. J. Am. Chem. Soc. 2001, 123, 5372. (b) Vigalok, A.;
Milstein, D. Organometallics 2000, 19, 2061.
(11) Vigalok, A.; Milstein, D. J. Am. Chem. Soc. 1997, 119, 7873.
(12) Vigalok, A.; Rybtchinski, B.; Gozin, Y.; Koblenz, T. S.; Ben-
David, Y.; Rozenberg, H.; Milstein, D. J. Am. Chem. Soc. 2003, 125,
15692.
The phenyldiazomethyl group is oriented in a 70°
angle relative to the coordination plane, perhaps due
to steric reasons. The presence of the bulky tert-butyl
groups on the phosphine arm can result in repulsive
interactions with the phenyl substituent. The diazo
carbon of complex 2 exhibits sp2 hybridization: N1-
C1-C2 (112.7°), N1-C1-Pt1 (123.5°), and C2-C1-Pt1
(122.8°).
(13) Vigalok, A.; Shimon, L. J. W.; Milstein, D. J. Am. Chem. Soc.
1998, 120, 477.
(14) Ashkenazi, N.; Vigalok, A.; Parthiban, S.; Ben-David, Y.;
Shimon, L. J. W.; Martin, J. M. L.; Milstein, D. J. Am. Chem. Soc.
2000, 122, 8797.
(15) (a) Vigalok, A.; Shimon, L. J. W.; Milstein, D. J. Am. Chem.
Soc. 1998, 120, 477. (b) Vigalok, A.; Rybtchinski, B.; Shimon, L. J. W.;
Ben-David, Y.; Milstein, D. Organometallics 1999, 18, 895. (c) Vigalok,
A.; Milstein, D. Organometallics 2000, 19, 2341. (d) Gandelman, M.;
Konstantinovski, L.; Rozenberg, H.; Milstein, D. Chem. Eur. J. 2003,
9, 2595.
(16) Gandelman, M.; Konstantinovski, L.; Rozenberg, H.; Milstein,
D.; Chem. Eur. J. 2003, 9, 2595.
(17) Poverenov, E.; Gandelman, M.; Shimon, L. J. W.; Rozenberg,
H.; Ben-David, Y.; Milstein, D. Chem. Eur. J. 2004, 10, 4673.
Another PCN-based platinum C-metalated diazo com-
plex, bearing the bulky electron-donating Me3Si sub-
stituent, was synthesized by the reaction of 1 with the
(18) Hughes, R. P.; Williamson, A.; Incarvito, C. D.; Rheingold, A.
L. Organometallics 2001, 20, 4741.

C-Metalated Diazoalkane Complexes of Pt
Organometallics, Vol. 24, No. 24, 2005 5939
Table 2. Selected Bond Lengths (Å) and Angles
(deg) of Complex 4
Bond Lengths
Pt(1)-C(1)
Pt(1)-P(1)
Pt(1)-P(2)
Pt(1)-Cl(1)
2.006(6)
C(1)-C(3)
P(1)-C(12)
C(15)-C(17)
C(1)-C(7)
1.843(6)
1.827(7)
1.537(10)
1.43(8)
2.275(17)
2.183(17)
2.436(14)
Bond Angles
C(1)-Pt(1)-P(1)
C(1)-Pt(1)-P(2)
P(1)-Pt(1)-Cl(1)
P(2)-Pt(1)-Cl(1)
84.0 (18)
83.6 (18)
96.2(5)
P(1)-N(1)-P(2)
C(1)-Pt(1)-Cl(1)
C(9)-P(1)-Pt(1)
C(8)-P(2)-Pt(1)
167.4(5)
177.7(16)
117.5(2)
102.0(2)
96.1(6)
Complex 4 was reacted with an in situ prepared THF
solution of PhCN2-Li+ at -30 °C. After 1 h the reaction
mixture was warmed to reach room temperature, re-
sulting in the formation of complex 5 (Scheme 2), which
was isolated and characterized by 31P, 1H, and 13C NMR
and IR spectroscopy. In the 31P{1H} NMR spectrum 5
gives rise to a singlet at 56.20 ppm with Pt satellites
(JPt-P ) 2778 Hz), and in the 13C{1H} NMR spectrum
the Pt[C(N2)Ph] carbon is observed as a doublet at
166.35 ppm (JP-C ) 4 Hz) while the ipso carbon exhibits
a triplet at 150.45 ppm (JP-C ) 1 Hz). The CN2
Figure 2. an ORTEP view of a molecule of complex 4 at
the 50% probability level. Hydrogen atoms are omitted for
clarity.
Scheme 2
absorption appears in the IR spectrum at 1968 cm-1
.
It is interesting to note that the diazo complexes 2,
3, and 5 are very stable and can be heated to more than
100 °C with no evidence of decomposition. This is quite
remarkable, considering the fact that most of the
diazoalkanes, excluding those bearing electron-with-
drawing groups such as diazocarbonyls, are unstable.
Apparently, R-metalation, as well as carbonyl group
substitution,21 stabilizes diazoalkanes due to the lower-
ing of electron density on the diazo carbon.
Reactivity of C-Coordinated Diazoalkane Com-
plexes. (a) Reactions with Cu(I). We were interested
in studying the possibility of N2 extrusion from the
C-metalated Pt complexes and the effect of the pincer
system on this process. Stable organic diazoalkane
compounds undergo dinitrogen extrusion at noticeably
lower temperatures in the presence of a catalyst, leading
to synthetically useful reactions.21 The development of
catalysts for diazo decomposition began in the 1960s
with the introduction of various copper compounds.22
In the present research we decided to use the copper(I)
triflate (Cu(OTf)) salt, which was introduced by Kochi
and Salomon as a highly active catalyst for diazo
decomposition.23
in situ prepared Me3SiC(N2)Li in THF at -30 °C
(Scheme 1). Warming the reaction mixture to room
temperature after 1 h revealed, on the basis of the 31P-
{1H} NMR spectrum, formation of the clean complex 3.
1
This complex was fully characterized by 31P, H, and
13C NMR and IR spectroscopy. 31P{1H} NMR exhibits a
singlet at 65.14 ppm with Pt satellites (JPt-P ) 4166
Hz), and in the 13C{1H} NMR spectrum the Pt[C(N2)-
SiMe3] carbon appears as a doublet at 155.94 ppm (JP-C
) 2 Hz), while the ipso carbon gives rise to a doublet at
149.60 ppm (JP-C ) 9 Hz). The CN2 absorption in the
IR spectrum was observed at 1956 cm-1
.
Formation of a C-Metalated Diazo Complex
Based on a PCP Ligand. For this purpose, the new
(PCP)PtCl complex 4 was first prepared. It was obtained
as a result of C-H activation and methane elimination
in the reaction of the PCP19 ligand with 1 equiv of
(COD)Pt(Me)Cl20 (Scheme 2). The reaction mixture was
heated in toluene at 140 °C for 12 h, resulting in a
colorless solution, the 31P{1H} NMR of which revealed
formation of complex 4. Pure 4 was characterized by 31P,
1H, and 13C NMR spectroscopy. The 31P{1H} NMR
spectrum of 4 exhibits a singlet at 58.51 ppm with Pt
satellites (JPt-P ) 2858 Hz), and in the 13C{1H} NMR
spectrum the ipso carbon gives rise to a triplet at 149.38
ppm (JP-C ) 11 Hz). X-ray-quality colorless crystals of
complex 4 were obtained by recrystallization from
pentane at room temperature. The single-crystal X-ray
study reveals a slightly distorted square planar struc-
ture (Figure 2); the P-Pt-Cl angles are about 96°, while
the P-Pt-C angles are approximately 84°. Selected
angles and bond lengths are given in Table 2.
When the rigid PCP-based complex 5 was reacted
with the complex Cu(OTf)(C6H6) in THF, decomposition
of 5 was detected by the disappearance of the CdNdN
signal in the IR spectrum and formation of a new
complex 6, as revealed by 31P{1H} NMR (Scheme 3).
Complex 6 was identified spectrally as (PCP)Pt(OTf),
and its structure was confirmed by an independent
synthesis.
Complex 6 can be alternatively synthesized by the
reaction of the corresponding methyl complex with triflic
(21) Doyle, M. P.; Forbes, D. C. Chem. Rev. 1998, 98, 911.
(22) (a) Moser, W. R. J. Am. Chem. Soc. 1969, 91, 1135. (b) Nozaki,
H.; Moriuti, S.; Yamabe, M.; Noyori, R. Tetrahedron Lett. 1966, 9. (c)
Nozaki, H.; Moriuti, S.; Takaya, H.; Noyori, R. Tetrahedron Lett. 1966,
5239. (d) Corey, E. J.; Myers, A. G.; Tetrahedron Lett. 1984, 25, 3559.
(e) Nugent, W. A.; Waller, F. J. Synth. Commun, 1988, 18, 61.
(23) (a) Salomon, R. G.; Kochi, J. K. J. Am. Chem. Soc. 1973, 95,
3300. (b) Salomon, R. G.; Kochi, J. K. J. Chem. Soc., Chem. Commun.
1972, 559.
(19) Rybtchinski, B.; Ben-David, Y.; Milstein, D. Organometallics
1997, 16, 3786.
(20) Clark, H. C.; Manzer, L. E. J. Organomet. Chem. 1973, 59, 411.

5940 Organometallics, Vol. 24, No. 24, 2005
Poverenov et al.
Scheme 3
the labile N arm that dissociates from the Pt center.
The resulting postulated ylide intermediate 2′′ can
undergo dimerization to generate complex 8 (Scheme
4). A similar mode of reactivity was observed with
C-metalated diazoalkane complexes of Rh5a and Ni.7
Upon photolysis of these complexes, dissociation of one
of the monodentate phosphine ligands took place, fol-
lowed by attack on the carbenoid intermediate and
dimerization.
Interestingly, the binuclear complex 8 can be cleaved
by reaction with triphenylphosphine to give products
analogous to those obtained in the PCP case. Thus,
addition of 1 equivalent of triphenylphosphine leads to
immediate disappearance of the green color and forma-
tion of (PCN)Pt(OTf)24 (9) and diphenylacetylene (Scheme
5). The PPh3 remains unchanged. While the mechanism
of dimer conversion to 9 is not clear, it is possible that
phosphine coordination to Pt results in bridge cleavage,
forming a carbenoid intermediate that undergoes dimer-
ization to yield diphenylacetylene.
In the case of complex 5, because of the strongly
coordinated phosphine arms of the PCP ligand, there
is no possibility of reaction of the carbenoid intermediate
with the phosphine and the system is stabilized by a
bimolecular reaction. Thus, by modification of the pincer
ligand it is possible to modify the reactivity of diazoalkyl
complexes.
(b) Reaction with Rh2(OAc)4. Decomposition of
diazoalkane compounds mediated by dirhodium(II) tet-
raacetate, Rh2(OAc)4, is well-known,21 and it was of
interest to us to explore its reactivity with the metalated
diazo complexes. Heating of complex 2 with Rh2(OAc)4
at 110 °C for 72 h resulted in formation of the novel
complex 10 (Scheme 6). In a competing reaction (PCN)-
Pt(OAc) (11) was also formed (ratio 10:11 ) 1:1).
Complex 11 was also independently and quantitatively
generated by heating of (PCN)PtMe17 with Rh2(OAc)4
at 110 °C for 72 h.
Complex 10 gives rise to a singlet at 62.68 ppm (JP-Pt
) 4222 Hz) in the 31P{1H} NMR spectrum, and in the
13C{1H} NMR spectrum it exhibits a singlet at 190.26
ppm and its ipso carbon is observed at 159.03 ppm as a
doublet (JP-C ) 10 Hz). The former 13C{1H} NMR signal
caused us to consider formation of an azine-type com-
pound, since a similar downfield chemical shift (192.88
ppm, singlet) of the sp2 CdN carbon was reported for
the azine compound (Me3Sn)(Ph)CdNNdC(Ph)(SnMe3),
generated by reaction of Me3Sn[(C(N2)Ph] with Rh2-
(OAc)4.25 Our suggestion was supported by ES-MS
spectroscopy, which exhibited a characteristic pattern
of azine-type dimer: m/z+ 1209.95 (complex 10 + 1),
1233.14 (10 + 1 + Na+), 1249.25 (10 + 1 + K+), 590.17
(1/2 of 10 - N2). A possible mechanism of complex 10
formation is shown in Scheme 7. Reaction with rhodium
acetate may lead to formation of an electrophilic Pt-
substituted Rh carbene, which is attacked by the
nucleophilic terminal nitrogen of another molecule of
complex 2 to give the azine-type complex 10.
acid (Scheme 3). When (PCP)PtCl (4) was reacted with
an ethereal solution of MeLi at room temperature in
THF, formation of (PCP)PtMe (7) was immediately
observed. This complex gives rise to a singlet at 57.47
ppm with Pt satellites (JPt-P ) 2902 Hz) in 31P{1H}
NMR, and its Pt-Me group is observed at -18.95 ppm
as a triplet (JP-C ) 8 Hz) in 13C{1H} NMR. Reaction of
complex 7 with 1 equiv of triflic acid at -30° C in
toluene, followed by warming to room temperature, led
to formation of complex 6. 31P{1H} NMR of 6 exhibits a
singlet at 65.30 ppm with Pt satellites (JPt-P ) 2897
Hz). In the 13C{1H} NMR spectrum the ipso carbon
appears as a triplet at 149.37 ppm (JP-C ) 9 Hz), and
in 19F NMR the triflate anion is observed at -75.11 ppm
as a broad singlet.
Apparently, reaction of complex 5 with Cu(I) results
in dinitrogen loss and formation of a reactive carbenoid
intermediate that undergoes bimolecular coupling to
generate diphenylacetylene, which was detected by GC
and GC/MS techniques. The resulting cationic [(PCP)-
Pt]+ species coordinates the triflate anion to give
complex 6.
In previous studies we have shown that hemilability
of a pincer ligand can strongly affect the properties of
its metal complex and can lead to unusual reactivity.17,24
In the current study we have observed significant
differences in the reactivity of the rigid PCP and
hemilabile PCN-based diazo complexes. Thus, an analo-
gous reaction of Cu(OTf)(C6H6) performed with the
hemilabile PCN-based complex 2 led to a completely
different type of product (Scheme 4). When 2 was
reacted with the Cu(I) complex in THF, the CdNdN
signal in the IR spectrum disappeared and formation
of a new complex was revealed by 31P{1H} NMR.
Workup yielded complex 8 as a green solid, which was
stable for several hours at room temperature and for
weeks at -20 °C. Its postulated structure is based on
NMR and ES-MS spectroscopy. It exhibits a singlet at
105.79 ppm with Pt satellites (JPt-P ) 2782 Hz) in 31P-
{1H} NMR, and in the 13C{1H} NMR spectrum, the two
bridging ylide carbons, which are different because of
the lack of a symmetry plane, appear as doublets at
156.72 ppm (JP-C ) 8 Hz) and at 156.51 ppm (JP-C ) 8
Hz). ES-MS spectroscopy shows signals at m/z+ 1329.49
(weak peak, complex 8 [1180] + OTf [149]), 590.25 (1/2
of 8), and 501.18 ((PCN)Pt).
In this case we believe that the unstable carbenoid
intermediate 2′, which may be formed as a result of N2
extrusion, undergoes an intramolecular reaction with
Summary
A series of the first C-coordinated diazoalkane com-
plexes of Pt, based on pincer-type PCN and PCP ligands,
(24) Poverenov, E.; Gandelman, M.; Shimon, L. J. W.; Rozenberg,
H.; Ben-David, Y.; Milstein, D. Organometallics 2005, 24, 1082.
(25) Wheeler, M. T. Ph.D. Thesis, The Ohio State University, 1990.

C-Metalated Diazoalkane Complexes of Pt
Organometallics, Vol. 24, No. 24, 2005 5941
Scheme 4
Scheme 5
Experimental Section
General Procedures. All experiments with metal com-
plexes and phosphine ligands were carried out under an
atmosphere of purified nitrogen in a Vacuum Atmospheres
glovebox equipped with an MO 40-2 inert gas purifier or using
standard Schlenk techniques. All solvents were reagent grade
or better. All nondeuterated solvents were refluxed over
sodium/benzophenone ketyl and distilled under an argon
atmosphere. Deuterated solvents were used as received. All
the solvents were degassed with argon and kept in the
glovebox over 4 Å molecular sieves. Commercially available
reagents were used as received. The precursor Pt(COD)(CH3)-
Cl was prepared according to a literature procedure.20 The
NMR spectra were recorded at 250 (1H), 101 (31P), and 235
MHz (19F) using a Bruker DPX 250 spectrometer, at 400 (1H),
100 (13C), 162 (31P), and 376 MHz (19F) using a Bruker AMX-
400 NMR spectrometer, and at 500 (1H), 126 (13C), and 202
MHz (31P) using a Bruker DPX 500 spectrometer. All spectra
Scheme 6
1
were recorded at 23 °C. H NMR and 13C{1H} NMR chemical
shifts are reported in parts per million downfield from tet-
ramethylsilane. 1H NMR chemical shifts were referenced to
the residual hydrogen signal of the deuterated solvents (7.15
ppm, benzene; 2.04 ppm, acetone). In 13C{1H} NMR measure-
ments the signals of C6D6 (128.0 ppm) and d6-acetone (206.0
ppm) were used as a reference. 31P NMR chemical shifts are
reported in ppm downfield from H3PO4 and referenced to an
external 85% solution of phosphoric acid in D2O. 19F NMR
chemical shifts were referenced to C6F6 (-163 ppm). Screw-
cap 5 mm NMR tubes were used in the NMR follow-up
experiments. Abbreviations used in the description of NMR
data are as follows: s, singlet; d, doublet; t, triplet; m,
multiplet.
was synthesized and fully characterized. These remark-
ably stable complexes were prepared by direct nucleo-
philic attack of RCN2-Li+ on (PCX)PtCl complexes.
Parallel reactivity studies of the hemilabile PCN-based
complex 2 and of the analogous rigid PCP-based com-
plex 5 with Cu(I) showed that the chemical behavior of
the carbenoid moiety is strongly influenced by the
nature of the pincer ligand. In the case of the rigid PCP-
based complex, bimolecular coupling of the carbenoid
moiety to generate diphenylacetylene and the complex
(PCP)Pt-OTf was observed, while the PCN-based car-
benoid was converted to the dimeric structure 8, forma-
tion of which was induced by the hemilability of the
amine ligand arm. Reaction of complex 2 with Rh2(OAc)4
led to formation of the stable azine-type complex 10.
Further reactivity of C-coordinated diazoalkane com-
plexes based on different pincer-type ligands is under
investigation.
Preparation of (PCN)Pt[C(N2)Ph] (2). To a THF solution
(1 mL) of Me3Sn[C(N2)Ph] (45 mg, 0.16 mmol) at - 30 °C was
added 100 µL of an nBuLi solution in hexane (1.6 M, 0.16
mmol) resulting in immediate appearance of the green color
of PhC(N2)Li. The resulting solution of PhC(N2)Li was added
to a THF solution (1 mL) of complex 117 (78 mg, 0.15 mmol) at
-30 °C. After 30 min the mixture was heated to room
temperature, resulting in a red solution. The 31P{1H} NMR
spectrum revealed formation of complex 2. The solvent was
evaporated, and the complex was washed with pentane and
dissolved in benzene. Benzene evaporation yielded 74 mg (0.12
mmol, 82% yield) of 2. X-ray-quality yellow crystals were
obtained from a benzene/pentane two-phase mixture at room
temperature.
1
31P{1H} NMR (C6D6): 63.11 (s, JP-Pt ) 4025 Hz). H NMR
(C6D6): 7.25 (d, JH-H ) 1 Hz, 1H, Ar), 7.23 (d, JH-H ) 1 Hz,

5942 Organometallics, Vol. 24, No. 24, 2005
Poverenov et al.
Scheme 7
1H, Ar), 7.22 (d, JH-H ) 1 Hz, 1H, Ar), 6.90 (t, JH-H ) 1 Hz,
2H, Ar), 6.88 (t, JH-H ) 1 Hz, 2H, Ar), 6.87 (t, JH-H ) 1 Hz,
1H, Ar),), 3.08 (m, 1H, CH2CH2N), 2.83 (m, 1H, CH2CH2N),
2.67 (d, JP-H ) 2 Hz, 2H, ArCH2P) 2.45 (d, JP-H ) 2 Hz, 3H,
NCH3), 2.32 (d, JH-P ) 2 Hz, 3H, NCH3), 2.25 (m, 1H, CH2-
CH2N), 1.84 (m, 1H, CH2CH2N), 1.27 (d, JP-H ) 14 Hz, 9 H,
PtBu), 0.88 (d, JP-H ) 14 Hz, 9 H, PtBu). 13C{1H} NMR
(C6D6): 157.92 (s, Pt-CdN2), 149.99(d, JP-C ) 1 Hz, ipso),
144.92 (s, Ar), 143.99 (s, Ar), 124.81 (s, Ar), 124.31 (s, Ar),
121.38 (s, Ar), 121.26 (s, Ar), 121.19 (s, Ar), 64.44 (s, CH2CH2N),
63.50 (s, CH2CH2N), 52.33 (d, JP-C ) 1 Hz, NCH3), 50.72 (d,
JP-C ) 1 Hz, NCH3), 37.21 (d, JP-C ) 34 Hz, ArCH2P), 35.00
(d, JP-C ) 30 Hz, PC(CH3)3), 34.59 (d, JP-C ) 30 Hz, PC(CH3)3),
29.61 (d, JP-C ) 4 Hz, PC(CH3)3), 29.31 (d, JP-C ) 4 Hz, PC-
(CH3)3). IR (film): ν(Pt-CdNdN) 1962 cm-1. Anal. Found
(calcd for C26H38N3PPt): C, 50.27 (50.43); H, 6.14 (6.03).
X-ray Structural Analysis of 2. Complex 2 was crystal-
lized from a benzene/pentane two-phase mixture at room
temperature to give yellow crystals. Crystal data: C26H38N3-
PPt, yellow, plate, 0.3 × 0.1 × 0.1 mm3, triclinic, P1h (No. 2), a
) 9.004(2) Å, b ) 11.345(2) Å, c ) 14.201(3) Å, R ) 72.53(3)°,
â ) 88.51(3)°, γ ) 77.85(3)° from 20 degrees of data, T ) 120(2)
K, V ) 1232.5(4) Å3, Z ) 2, fw ) 618.65, Dc ) 1.667 Mg/m3, µ
) 5.774 mm-1. Data collection and treatment: Nonius Kap-
paCCD diffractometer, Mo KR (λ ) 0.710 73 Å), graphite
monochromator, 17 632 reflections collected, -11< h < 11, -12
< k < 12, 0 < l < 17, frame scan width 1.0°, scan speed 1° per
100 s, typical peak mosaicity 2.08°, 3542 independent reflec-
tions (Rint ) 0.057). The data were processed with Denzo-
Scalepack. Solution and refinement: structure solved by direct
methods with SHELXS-97, full-matrix least-squares refine-
ment based on F2 with SHELXL-97, 288 parameters with 0
restraints, final R1 ) 0.0439 (based on F2) for data with I >
2σ(I) and R1 ) 0.0515 on all 4931 reflections, wR2 ) 0.0938,
goodness of fit on F2 1.019, largest electron density peak 1.629
e/Å3.
36.90 (d, JP-C ) 35 Hz, ArCH2P), 34.53 (d, JP-C ) 32 Hz,
PC(CH3)3), 34.16 (d, JP-C ) 30 Hz, PC(CH3)3), 29.76 (d, JP-C
) 3 Hz, PC(CH3)3), 28.99 (d, JP-C ) 3 Hz, PC(CH3)3), 0.17 (s,
Si(CH3)3) (assignment of 13C{1H} NMR signals was confirmed
by 13C DEPT). IR (film): ν(Pt-CdNdN) 1956 cm-1. Anal.
Found (calcd for C23H42N3PSiPt): C, 45.08 (44.92); H, 6.87
(6.83).
Formation of (PCP)PtCl (4). To a toluene solution (3 mL)
of the ligand C6H3(P(iPr)2)2 (110 mg, 0.33 mmol) was added
106 mg (0.30 mmol) of (COD)Pt(Cl)CH3. The reaction mixture
was heated at 140 °C for 12 h, resulting in a colorless solution.
31P{1H} NMR revealed formation of complex 4. The solvent
was evaporated, and the complex was washed with pentane
and dissolved in benzene. After benzene evaporation 144 mg
(0.26 mmol, 85% yield) of 4 was obtained.
1
31P{1H} NMR (C6D6): 58.51 (s, JP-Pt ) 2858 Hz). H NMR
(C6D6): 7.10 (t, JH-H ) 7 Hz, 1H, Ar), 6.85 (d, JH-H ) 7 Hz,
2H, Ar), 2.70 (t, JP-H ) 4 Hz, 4H, P(CH(CH3)2)2), 2.19 (m, 4H,
ArCH2P), 1.35 (dd, JP-H ) 7 Hz, JP-H ) 15 Hz, 12 H, P(CH-
(CH3)2)), 0.86 (dd, JP-H ) 7 Hz, JP-H ) 15 Hz, 12 H, P(CH-
(CH3)2)). 13C{1H} NMR (C6D6): 149.38 (t, JP-C ) 11 Hz, ipso),
128.29 (s, Ar), 124.18 (s, Ar), 122.50 (s, Ar), 122.43 (s, Ar),
122.35 (s, Ar), 33.34 (t, JP-C ) 15 Hz, ArCH2P), 23.95 (t, JP-C
) 14 Hz, P(CH(CH3)2)2), 18.42 (t, JP-C ) 2 Hz, P(CH(CH3)2)2),
17.78 (t, JP-C ) 12 Hz, P(CH(CH3)2)2 (assignment of 13C{1H}
NMR signals was confirmed by 13C DEPT). Anal. Found (calcd
for C20H35P2PtCl): C, 42.21 (42.29); H, 6.13 (6.17).
X-ray Structural Analysis of 4. Complex 4 was crystal-
lized from a pentane solution at room temperature to give
white/colorless crystals. Crystal data: (C20H35Cl1P2Pt)2, white/
colorless, 1.0 × 0.8 × 0.2 mm3, triclinic, P1h (No. 2), a ) 11.148-
(2) Å, b ) 13.935(3) Å, c ) 14.683(3) Å, R ) 78.16(3)°, â )
82.35(3)°, γ ) 89.33(3)° from 20 degrees of data, T ) 120(2)
K, V ) 2212.3(8) Å3, Z ) 4, fw ) 567.96, Dc ) 1.705 Mg/m3, µ
) 6.608 mm-1. Data collection and treatment: Nonius Kap-
paCCD diffractometer, Mo KR (λ ) 0.710 73 Å), graphite
monochromator, 43 811 reflections collected, -12 < h <13, -15
< k < 16, 0 < l < 17, frame scan width 1.0°, scan speed 1° per
30 s, typical peak mosaicity 0.535°, 11 008 independent
reflections (Rint ) 0.117). The data were processed with Denzo-
Scalepack. Solution and refinement: structure solved by direct
methods with SHELXS, full-matrix least-squares refinement
based on F2 with SHELXL-97, 449 parameters with 0 re-
straints, final R1 ) 0.0378 (based on F2) for data with I > 2σ-
(I) and R1 ) 0.0508 on 6834 reflections, wR2 ) 0.1104,
goodness of fit on F2 ) 1.043, largest electron density peak
2.047 e/Å3.
Formation of (PCN)Pt[C(N2)SiMe3] (3). To a THF solu-
tion (0.5 mL) of Me3Si(CN2)H (80 µL of a 2 M solution in
toluene, 0.16 mmol) at - 30 °C was added 107 µL of a MeLi
solution in ether (1.5 M, 0.16 mmol), and Me3SiCN2Li was
immediately formed. The solution of the in situ prepared Me3-
SiC(N2)Li was added to a THF solution (1 mL) of (PCN)PtCl
complex (78 mg, 0.15 mmol) at - 30 °C. After 1 h the mixture
was heated to room temperature and the 31P{1H} NMR
spectrum revealed the formation of clean complex 3. The
solvent was evaporated, and the complex was extracted with
pentane. Pentane evaporation yielded 83 mg (0.13 mmol, 89%
yield) of complex 3.
Formation of (PCP)Pt[C(N2)Ph] (5). A solution of in situ
prepared (as described above, in the preparation of complex
2) PhCN2Li (0.17 mmol) was added to a THF solution (1 mL)
of complex 4 (85 mg, 0.15 mmol) at -30 °C. After 1 h the
mixture was warmed to room temperature, resulting in a red
solution. The 31P{1H} NMR spectrum revealed formation of
clean complex 5. The solvent was evaporated, and the complex
was washed with pentane and dissolved in benzene. Benzene
evaporation yielded 78 mg (0.12 mmol, 80% yield) of 5.
1
31P{1H} NMR (C6D6): 65.14 (s, JP-Pt ) 4166 Hz). H NMR
(C6D6): 7.03 (t, JH-H ) 6 Hz, 1H, Ar), 6.89 (d, JH-H ) 6 Hz,
1H, Ar), 6.87 (d, JH-H ) 6 Hz, 1H, Ar), 3.11 (m, 1 H, CH2CH2N),
2.78 (m, 1 H, CH2CH2N), 2.67 (d, JP-H ) 2 Hz, 2H, ArCH2P)
2.62 (d, JP-H ) 2 Hz, 3H, NCH3), 2.51(d, JP-H ) 2 Hz, 3H,
NCH3), 2.24 (m, 1H, CH2CH2N), 1.89 (m, 1H, CH2CH2N), 1.42
(d, JP-H ) 14 Hz, 9 H, PtBu), 1.00 (d, JP-H ) 14 Hz, 9 H, PtBu),
0.43 (s, 9 H, Si(CH3)3). 13C{1H} NMR (C6D6): 155.94 (d, JP-C
) 2 Hz, Pt-CdN2), 149.60 (d, JP-C ) 9 Hz, ipso), 144.17 (s,
Ar), 125.42 (s, Ar), 124.47 (s, Ar), 123.61 (s, Ar), 121.00 (d,
JP-C ) 16 Hz, Ar), 67.54 (s, CH2CH2N), 64.44 (s, CH2CH2N),
52.25 (d, JP-C ) 1 Hz, NCH3), 49.52 (d, JP-C ) 1 Hz, NCH3),
1
31P{1H} NMR (C6D6): 56.20 (s, JP-Pt ) 2778 Hz). H NMR
(C6D6): 7.63 (d, JH-H ) 1 Hz, 1H, Ar), 7.51 (d, JH-H ) 1 Hz,
1H, Ar), 7.27 (s, 2 H, Ar), 7.25 (s, 1H, Ar), 6.92 (t, JH-H ) 2
Hz, 1H, Ar), 6.87 (d, JH-H ) 2 Hz, 1H, Ar), 6.80 (t, JH-H ) 2

C-Metalated Diazoalkane Complexes of Pt
Organometallics, Vol. 24, No. 24, 2005 5943
Hz, 1H, Ar), 2.93 (t, JP-H ) 4 Hz, 4H, P(CH(CH3)2)2), 1.97 (m,
4H, ArCH2P), 1.05 (dd, JP-H ) 6 Hz, JP-H ) 8 Hz, 12 H, P(CH-
(CH3)2)), 0.83 (dd, JP-H ) 6 Hz, JP-H ) 8 Hz, 12 H, P(CH-
(CH3)2)). 13C{1H} NMR (C6D6): 166.35 (d, JP-C ) 4 Hz, Pt-
CdN2), 150.45 (t, JP-C ) 1 Hz, ipso), 146.46 (s, Ar), 125.64 (s,
Ar), 125.08 (s, Ar), 124.90 (s, Ar), 121.75 (t, JP-C ) 3 Hz, Ar),
120.92 (s, Ar), 36.53 (t, JP-C ) 16 Hz, ArCH2P), 25.02 (t, JP-C
) 15 Hz, P(CH(CH3)2)2), 18.10 (t, JP-C ) 1 Hz, P(CH(CH3)2)2),
17.73 (t, JP-C ) 4 Hz, P(CH(CH3)2)2. IR (film): ν(Pt-CdN2)
1968 cm-1. Anal. Found (calcd for C27H40N2P2Pt): C, 49.84
(49.42); H, 6.14 (6.16); N, 4.26 (4.31).
green solid was washed with pentane and benzene and
dissolved in THF. Evaporation of THF yielded 31 mg (0.053
mmol, 82% yield) of complex 8. NMR measurements have been
performed at -30 °C, since decomposition of complex 8 starts
after several hours at room temperature.
31P{1H} NMR (d6-acetone): 105.79 (s, JP-Pt ) 2782 Hz). 1H
NMR (C6D6): the aromatic and ligand arms region is unre-
solved; 1.16 (d, JP-H ) 6 Hz, 9 H, P(tBu)2), 1.09 (d, JP-H ) 6
Hz, 9 H, P(tBu)2). 13C{1H} NMR (C6D6): 156.72 (d, JP-C ) 8
Hz, Pt-C-Pt), 156.51 (d, JP-C ) 8 Hz, Pt-C-Pt), 148.44 (s,
ipso), 146.87 (s, ipso), 145.25 (s, Ar), 143.82 (s, Ar), 143.25 (s,
Ar), 141.10 (s, Ar), 138.27 (s, Ar), 136.49 (s, Ar), 134.13 (s, Ar),
133.76 (s, Ar), 132.29 (s, Ar), 132.02 (s, Ar), 130.90 (s, Ar),
130.86 (s, Ar), 130.73 (s, Ar), 130.57 (s, Ar), 130.49 (s, Ar),
130.25 (s, Ar), 129.97 (s, Ar), 129.88 (s, Ar), 129.57 (s, Ar),
128.98 (s, Ar), 128.87 (s, Ar), 126.81 (s, Ar), 64.67 (s,
ArCH2CH2N), 63.68 (s, ArCH2CH2N), 59.65 (s, ArCH2CH2N),
59.54 (s, ArCH2CH2N), 50.79 (s, N(CH3)2), 50.72 (s, N(CH3)2),
43.63 (d, JP-C ) 42 Hz, ArCH2P), 43.57 (d, JP-C ) 42 Hz,
Formation of (PCP)Pt-OTf (6). To a toluene solution (1
mL) of complex 7 (40 mg, 0.073 mmol) was added 1 equiv of
HOTf (6.5 µL, 0.073 mmol) at -30 °C. After 3 h the solution
was warmed to room temperature and the solvent was
evaporated. Complex 6 was washed with pentane and dis-
solved in benzene. Benzene evaporation yielded 43 mg (0.063
mmol, 87% yield) of complex 6.
1
31P{1H} NMR (C6D6): 65.30 (s, JP-Pt ) 2897 Hz). H NMR
ArCH2P), 39.65 (d, JP-C ) 16 Hz, P(C(CH3)3), 39.05 (d, JP-C
)
(C6D6): 6.96 (t, JH-H ) 3 Hz, 1H, Ar), 6.80 (d, JH-H ) 3 Hz,
2H, Ar), 2.51 (t, JP-H ) 4 Hz, 4H, ArCH2P), 2.30 (m, 4H,
P(CH(CH3)2)2), 1.31 (dd, JP-H ) 10 Hz, JP-H ) 8 Hz, 12 H,
P(CH(CH3)2)), 0.77 (dd, JP-H ) 8 Hz, JP-H ) 7 Hz, 12 H, P(CH-
(CH3)2)). 13C{1H} NMR (C6D6): 149.37 (t, JP-C ) 9 Hz, ipso),
127.45 (s, Ar), 125.48 (s, Ar), 122.88 (t, JP-C ) 9 Hz, Ar), 122.81
(s, Ar), 31.91 (t, JP-C ) 15 Hz, ArCH2P), 24.68 (t, JP-C ) 15
Hz, P(CH(CH3)2)2), 18.57 (t, JP-C ) 3 Hz, P(CH(CH3)2)2), 17.81
(s, PtSO3CF3). 19F NMR (C6D6): -75.11 (s, Pt-SO3CF3). Anal.
Found (calcd for C21H35P2PtO3SF3): C, 36.81 (37.00); H, 5.12
(6.14).
30 Hz, P(C(CH3)3), 28.97 (d, JP-C ) 5 Hz, P(C(CH3)3). ES-MS:
m/z+ 1329.49 (M + OTf, weak peak) (calcd 1329.8), 590.25 (1/2
M) (calcd 590.35), 501.18 (PCNPt) (calcd 501.35).
Reaction of Complex 8 with PPh3. When a THF solution
(0.5 mL) of complex 8 (40 mg, 0.068 mmol for the monomeric
unit) was reacted with a THF solution (0.5 mL) of PPh3 (18
mg, 0.068 mmol), the green color immediately disappeared and
the solution became brown. 31P{1H} NMR revealed formation
of (PCN)Pt(OTf) (9), which was characterized by NMR, show-
ing data identical with those of the reported compound,24 and
formation of diphenylacetylene was detected by GC.
Reaction of (PCN)Pt[C(N2)Ph] (2) with Rh2(OAc)4.
Formation of ({PCN}Pt)(Ph)CdNNdC(Ph)(Pt{PCN}) (10).
To a toluene solution (1 mL) of (PCN)Pt[C(N2)Ph] (2; 20 mg,
0.035 mmol) was added 14 mg (0.035 mmol) of Rh2(OAc)4, and
the reaction mixture was heated at 110 °C for 72 h. The
31P{1H} NMR spectrum revealed the disappearance of complex
2 and formation of two new complexes, (PCN)Pt(OAc) (11;
structurally confirmed by independent synthesis) and [(PCN)-
PtPhCN]2 (10). The solvent was evaporated, and the gray solid
was washed with pentane and dissolved in benzene. Solvent
evaporation yielded 10 in 50% yield according to the 31P{1H}
NMR of the mixture.
Synthesis of (PCP)Pt-Me (7). To a toluene solution (1
mL) of complex 4 (30 mg, 0.053 mmol) was added 58 µL (0.088
mmol) of a 1.5 M MeLi solution in ether, and formation of
complex 7 was immediately revealed by 31P{1H} NMR. The
solvent was evaporated, and complex 7 was extracted with
pentane. Solvent evaporation yielded 27 mg (0.050 mmol, 95%
yield) of complex 7. This complex was unstable under high
vacuum, and an acceptable elemental analysis could not be
obtained.
1
31P{1H} NMR (C6D6): 57.47 (s, JP-Pt ) 2902 Hz). H NMR
(C6D6): 7.14 (bs, 2 H, Ar), 7.03 (bs, 1H, Ar), 2.51 (t, JP-H ) 4
Hz, 4H, ArCH2P), 2.30 (m, 4H, P(CH(CH3)2)2), 1.31 (dd, JP-H
) 6 Hz, JP-H ) 8 Hz, 12 H, P(CH(CH3)2)), 0.77 (dd, JP-H ) 6
Hz, JP-H ) 8 Hz, 12 H, P(CH(CH3)2)), the PtCH3 signal is
obscured under the P(CH(CH3)2 signal pattern. 13C{1H} NMR
(C6D6): 149.40 (t, JP-C ) 7 Hz, ipso), 128.52 (s, Ar), 123.44 (s,
Ar), 121.21 (s, Ar), 121.14 (s, Ar), 122.07 (s, Ar), 38.72 (t, JP-C
) 16 Hz, ArCH2P), 24.03 (t, JP-C ) 14 Hz, P(CH(CH3)2)2), 18.50
(t, JP-C ) 3 Hz, P(CH(CH3)2)2), 17.90 (t, JP-C ) 4 Hz, P(CH-
(CH3)2)2), -18.95 (s, JPt-C ) 8 Hz, Pt-CH3) (assignment of
13C{1H} NMR signals was confirmed by 13C DEPT).
Reaction of (PCP)Pt[C(N2)Ph] (5) with Cu(OTf)(C6H6).
When a red THF solution (0.5 mL) of complex 5 (40 mg, 0.068
mmol) was reacted with a THF solution (0.5 mL) of Cu(OTf)-
(C6H6) (34 mg 0.068 mmol), the red color immediately disap-
peared and the solution became brown. 31P{1H} NMR revealed
formation of (PCP)Pt(OTf) (6), while signals of the CN2 group
in the IR spectrum disappeared. Formation of diphenylacety-
lene was observed by GC and CG/MS. Complex 6 was
characterized by NMR and ES-MS spectroscopy, and its
structure was also confirmed by independent synthesis. MS:
m/z+ 532.48 (M - OTf) (calcd 532.16), 148.82 (OTf) (calcd
149.07). The NMR data are identical with those reported above
in the independent synthesis procedure.
Selected NMR data for complex 10 are as follows. 31P{1H}
NMR (C6D6): 62.68 (s, JP-Pt ) 4222 Hz). 1H NMR (C6D6): 7.12
(d, JH-H ) 7 Hz, 2 H, Ar), 7.07 (d, JH-H ) 7 Hz, 2H, Ar), 6.81
(d, JH-H ) 7 Hz, 1H, Ar), 6.61 (t, JH-H ) 5 Hz, 1H, Ar), 6.52 (t,
JH-H ) 5 Hz, 1H, Ar), 6.45 (d, JH-H ) 5 Hz, 1H, Ar), 1.30 (d,
JP-H ) 14 Hz, 18H, P(tBu)2). 13C{1H} NMR (C6D6): 190.26 (s,
Pt-CdN2), 159.03 (d, JP-C ) 10 Hz, ipso), 142.47 (s, Ar), 139.65
(s, Ar), 139.40 (s, Ar), 139.15 (s, Ar), 137.82 (s, Ar), 132.08 (d,
JP-C ) 5 Hz, Ar), 130.75 (s, Ar), 125.12 (s, Ar), 124.15 (s, Ar),
63.49 (s, ArCH2CH2N), 63.49 (s, ArCH2CH2N), 49.02 (s,
N(CH3)2), 49.00 (s, N(CH3)2), 34.49 (d, JP-C ) 50 Hz, ArCH2P),
33.51 (d, JP-C ) 50 Hz, P(C(CH3)3), 28.95 (d, JP-C ) 5 Hz,
P(C(CH3)3). ES-MS: m/z+ 1209.95 (M + 1) (calcd 1209.71),
1233.14 (M + 1 + Na+) (calcd 1232.70), 1249.25 (M + 1 + K+)
(calcd 1248.81), 590.17 (1/2 M - N2) (calcd 590.35).
Synthesis of (PCN)Pt(OAc) (11). A toluene solution (2
mL) of (PCN)PtCH317 (35 mg, 0.068 mmol) and Rh2(OAc)4 (30
mg, 0.068 mmol) was heated at 110 °C for 72 h. The 31P{1H}
NMR spectrum revealed complete conversion to complex 11.
The solvent was evaporated, and the gray solid was washed
with pentane and was dissolved in benzene. Solvent evapora-
tion yielded 33 mg (0.059 mmol, 87% yield) of 11. This complex
was unstable under high vacuum, and an acceptable elemental
analysis could not be obtained.
Reaction of (PCN)Pt[C(N2)Ph] (2) with Cu(OTf)(C6H6).
Formation of Complex 8. To a THF solution (1 mL) of
complex 2 (40 mg, 0.065 mmol) was added a THF solution (1
mL) of Cu(OTf)(C6H6) (32 mg, 0.065 mmol). The solution
immediately became green, and 31P{1H} NMR revealed forma-
tion of a new complex, while the CN2 absorption in the IR
spectrum disappeared. The solvent was evaporated, and the
1
31P{1H} NMR (C6D6): 64.18 (s, JP-Pt ) 4175 Hz). H NMR
(C6D6): 7.08 (t, JH-H ) 3 Hz, 1H, Ar), 7.01(d, JH-H ) 3 Hz,
1H, Ar), 6.76 (d, JH-H ) 3 Hz, 1H, Ar), 2.69 (m, 2 H, CH2CH2N),
2.68 (d, JP-H ) 9 Hz, 2H, ArCH2P), 2.52 (s, 3H, NCH3), 2.51

5944 Organometallics, Vol. 24, No. 24, 2005
Poverenov et al.
(s, 3H, NCH3), 2.26 (s, 3 H, CO2CH3), 1.23 (d, JP-H ) 13 Hz,
18 H, PtBu). 13C{1H} NMR (C6D6): 175.08 (s, CO2CH3), 150.81
(d, JP-C ) 1 Hz, ipso), 143.30 (s, Ar), 124.73 (s, Ar), 123.80 (s,
Ar), 121.64 (s, Ar), 121.51 (s, Ar), 63.76 (s, CH2CH2N), 63.76
(s, CH2CH2N), 49.66 (s, NCH3), 49.64 (s, NCH3), 48.85 (d, JP-C
) 40 Hz, ArCH2P), 36.21 (s, CO2CH3), 34.27 (d, JP-C ) 25 Hz,
PC(CH3)3), 29.05 (d, JP-C ) 3 Hz, PC(CH3)3. IR (film): ν(Pt-
program for German-Israeli cooperation, and by the
Helen and Martin Kimmel Center for Molecular Design.
D.M. is the holder of the Israel Matz Professorial Chair
of Organic Chemistry.
Supporting Information Available: CIF files containing
X-ray crystallographic data for complexes 2 and 4. This
material is available free of charge via the Internet at
http://pubs.acs.org.
CdO(OCH3)) 1623 cm-1
.
Acknowledgment. This work was supported by the
Israel Science Foundation, Jerusalem, Israel, by the DIP
OM050637X