Functionalization of η1,η2-Bridging Cyaphide (C≡P)- Ligands: Trinuclear η1,η1,η2-Bridging Cyaphide and Dinuclear Bridging Isocyaphide (C≡PR) Complexes of Platinum

Article abstract of DOI:10.1021/om980746u

The oxidative addition reaction of Pt(PEt₃)₄ with Cl₂C=PN(SiMe₃)₂ at low temperature (-50 °C) forms the η¹-phosphavinyl complex cis-Cl(Et₃P)₂Pt[C(Cl)=PN(SiMe₃)₂] (Ia), which isomerizes to the trans-isomer (Ib) upon warming to 0 °C; the structure of Ib was determined by X-ray diffraction studies. Complex Ib reacts with Pt(PEt₃)₂Cl₂ in the presence of 3 equiv of sodium benzophenone to generate the bridging, dinuclear η¹,η²-cyaphide complex Cl(Et₃P)₂-Pt(μ-η¹,η ²-C≡P)Pt(PEt₃)₂ (II) in good yield, providing a much simpler and higher yield preparation of II, which was synthesized and characterized previously by a more circuitous route. Compound II reacts with 0.5 equiv of [Cl₂Pt(PEt₃)]₂ or with 1 equiv of W(CO)₅(THF) to generate the trinuclear metal-cyaphide complexes Cl(Et₃P)₂Pt[μ-η¹,η ¹,η²-C≡P{Pt(PEt₃)-(Cl) ₂}]Pt(PEt₃)₂ (III) and Cl(Et₃P)₂Pt[μ-η¹,η ¹,η²-C≡P{W(CO)₅}]Pt(PEt ₃)₂ (IV), respectively, in which the lone pair of electrons on the C≡P phosphorus atom is coordinated to a Pt-(PEt₃)(Cl)₂ fragment in the former and to a W(CO)₅ fragment in the latter; the structure of IV was determined by X-ray diffraction studies. Compound II also reacts with MeI to form the methyl isocyaphide complex (Cl)(Et₃P)Pt(μ-C=PMe)Pt(PEt₃)₂(I) (Vc), in which the cyaphide (C≡P^-) ligand is converted to a methyl isocyaphide (C≡PMe) ligand in a semibridging coordination mode. When compound II is reacted with MeOTf, the product is the cationic isocyaphide complex [(Cl)(Et₃P)₂Pt(μ-η¹,η ²-C≡PMe)Pt(PEt₃)₂](OTf) (Va), which is likely coordinated in an η¹,η²-bridging mode. Compound Va reacts with NaI to form Vc, which suggests that Va forms as an intermediate before Vc in the reaction of II with MeI. ? Dedicated to Professor Helmut Werner on the occasion of his 65th birthday.

Full text of DOI:10.1021/om980746u

2
58
Organometallics 1999, 18, 258-267
1
2
-
F u n ction a liza tion of η ,η -Br id gin g Cya p h id e (CtP )
1
1
2
Liga n d s: Tr in u clea r η ,η ,η -Br id gin g Cya p h id e a n d
Din u clea r Br id gin g Isocya p h id e (CtP R) Com p lexes of
†
P la tin u m
‡
Wayde V. Konze, Victor G. Young, J r., and Robert J . Angelici*
Department of Chemistry, Iowa State University, Ames, Iowa 50011
Received September 1, 1998
The oxidative addition reaction of Pt(PEt
3
)
4
with Cl
-50 °C) forms the η -phosphavinyl complex cis-Cl(Et P)
isomerizes to the trans-isomer (Ib) upon warming to 0 °C; the structure of Ib was determined
2
CdPN(SiMe
3
)
2
at low temperature
1
(
3
2
Pt[C(Cl)dPN(SiMe
3 2
)
] (Ia ), which
by X-ray diffraction studies. Complex Ib reacts with Pt(PEt
of sodium benzophenone to generate the bridging, dinuclear η ,η -cyaphide complex Cl(Et
3
1
)
2
Cl
2
in the presence of 3 equiv
2
P) -
2
3
1
2
Pt(µ-η ,η -CtP)Pt(PEt
preparation of II, which was synthesized and characterized previously by a more circuitous
route. Compound II reacts with 0.5 equiv of [Cl Pt(PEt )] or with 1 equiv of W(CO) (THF)
to generate the trinuclear metal-cyaphide complexes Cl(Et Pt[µ-η ,η ,η -CtP{Pt(PEt )-
}]Pt(PEt (IV), respectively,
in which the lone pair of electrons on the CtP phosphorus atom is coordinated to a Pt-
PEt )(Cl) fragment in the former and to a W(CO) fragment in the latter; the structure of
IV was determined by X-ray diffraction studies. Compound II also reacts with MeI to form
the methyl isocyaphide complex (Cl)(Et P)Pt(µ-CdPMe)Pt(PEt (I) (Vc), in which the
3 2
) (II) in good yield, providing a much simpler and higher yield
2
3
2
5
1
1
2
3
P)
Pt[µ-η ,η ,η -CtP{W(CO)
2
3
1
1
2
(
Cl)
2
}]Pt(PEt
3
)
2
(III) and Cl(Et
3
P)
2
5
3 2
)
(
3
2
5
3
3 2
)
-
cyaphide (CtP ) ligand is converted to a methyl isocyaphide (CtPMe) ligand in a
semibridging coordination mode. When compound II is reacted with MeOTf, the product is
the cationic isocyaphide complex [(Cl)(Et
is likely coordinated in an η ,η -bridging mode. Compound Va reacts with NaI to form Vc,
which suggests that Va forms as an intermediate before Vc in the reaction of II with MeI.
1
2
3
P)
2
3 2
Pt(µ-η ,η -CtPMe)Pt(PEt ) ](OTf) (Va ), which
1
2
In tr od u ction
Studies involving phosphorus analogues of common
organic ligands have evolved at a very rapid pace
recently, and coordination compounds of C-P analogues
of almost all C-C multiple bond ligands are now known,
including phosphaalkenes, phosphaalkynes, phospha-
allyls, phosphaallenes, phosphabutadienes, phospha-
These phosphorus compounds have been calculated to
be high energy species; the heat of formation of (CtP)
-
(
cyaphide anion) is calculated to be ca. 40 kcal/mol less
- 10
exothermic than that of (CtN) , and CtPH (iso-
cyaphide) is calculated to be 85 kcal/mol less stable than
11
its isomer H-CtP (phosphaalkyne). Nevertheless, we
recently succeeded in preparing the first example of a
coordinated isocyaphide ligand by oxidative addition of
the C-Cl bond in the phosphavinyl complex 1 (eq 1) to
cyclopropenes, phosphacyclobutadienes, phosphacyclo-
pentadienyls, and phosphaarenes.1
-6
However, phos-
-
phorus analogues of the well-studied cyanide (CtN)
and isocyanide (CtNR) ligands have been limited.
7
-9
†
Dedicated to Professor Helmut Werner on the occasion of his 65th
birthday.
‡
X-ray Crystallographic Laboratory, Chemistry Department, Uni-
versity of Minnesota, Minneapolis, MN 55455.
1) Appel, R. In Multiple Bonds and Low Coordination in Phospho-
rus Chemistry; Regitz, M., Scherer, O. J ., Eds.; Thieme: Stuttgart,
990; pp 157-219.
2) Bickelhaupt, F. In Multiple Bonds and Low Coordination in
(
1
(
Phosphorus Chemistry; Regitz, M., Scherer, O. J ., Eds.; Thieme:
Stuttgart, 1990; pp 195-199.
generate a diplatinum complex [(Cl)(Et3P)Pt(µ-CdPR)-
Pt(PEt3)2(Cl)] (2), in which the isocyaphide ligand
exhibits a semibridging coordination mode. However,
this preparation was limited by the few examples of
dichlorophosphaalkenes that are available and by the
(
3) Burckett-St. Laurent, J . C. T. R.; Hitchcock, P. B.; Kroto, H. W.;
9
Meidine, M. F.; Nixon, J . F. J . Organomet. Chem. 1982, 238, C82.
(
(
(
(
4) Mathey, F. New J . Chem. 1987, 11, 585-593.
5) Nixon, J . F. Chem. Rev. 1988, 88, 1327.
6) Nixon, J . F. Coord. Chem. Rev. 1995, 145, 201-258.
7) Weber, L.; Schumann, I.; Schmidt, T.; Stammler, H. G.; Neu-
mann, B. Z. Anorg. Allg. Chem. 1993, 619, 1759-64.
8) Weber, L.; Schumann, I.; Stammler, H.-G.; Neumann, B. Chem.
Ber. 1994, 127, 1349-53.
(9) J un, H.; Angelici, R. J . Organometallics 1994, 13, 2454-60.
(10) Pyykk o¨ , P.; Zhao, Y. Mol. Phys. 1990, 70, 701.
(11) Nguyen, M. T.; Ha, T. K. J . Mol. Struct. 1986, 139, 145.
(
1
0.1021/om980746u CCC: $18.00 © 1999 American Chemical Society
Publication on Web 12/30/1998

1
2
-
η ,η -Bridging Cyaphide (CtP) Ligands
Organometallics, Vol. 18, No. 2, 1999 259
bulky R-groups that are incorporated in these reagents.
More recently, Weber and co-workers reported the
synthesis (eq 2) of some diiron complexes containing
(
SiMe3)2 in THF or hexanes at -50 °C immediately and
symmetrically bridged isocyaphide ligands (3) by a
different route. In these reactions, the isocyaphide
products were stable only when bulky R-groups were
present on phosphorus. We also obtained the first
example of a cyaphide complex (Et3P)2ClPt(CtP) (4)
from a reaction (eq 3) of the phosphavinyl complex (1)
1
quantitatively forms the η -phosphavinyl complex cis-
Cl(Et3P)2Pt[C(Cl)dPN(SiMe3)2] (Ia ) by oxidative addi-
tion of one of the C-Cl bonds; upon warming the
solution to 0 °C, the cis-isomer completely rearranges
to the trans-isomer (Ib). Some formation of Pt(PEt3)2-
Cl2 also occurs during this reaction. This cis-trans
isomerization is quite similar to that in the analogous
phosphavinyl complex Cl(Et3P)2Pt[C(Cl)dPMes*], in
which both the cis- and trans-isomers were isolated and
7
1
2
31
characterized. The structure and P NMR spectrum
of Ib are very similar to those of trans-Cl(Et3P)2Pt-
[
C(Cl)dPMes*] (1), but they differ in reactivity. For
with Pd(PEt3)4, in which the Mes* group was trans-
instance, compound 1 rearranges to Mes*CtP and
Pt(PEt3)2Cl2 after 24 h in THF at room temperature,
whereas Ib is stable in THF for weeks at room temper-
ature, although a small amount of Pt(PEt3)2Cl2 does
form in this time. Further, compound 1 undergoes a
second C-Cl oxidative addition reaction (eq 1) with
Pt(PEt3)4 in 24 h at room temperature to form the
isocyaphide complex [(Cl)(Et3P)Pt(µ-CdPMes*)Pt(PEt3)2-
(Cl)] (2); a similar reaction between Ib and Pt(PEt3)4
does not form the N(SiMe3)2 analogue of compound 2,
but results in decomposition to a complex mixture of
unidentified products.
ferred from phosphorus to palladium forming (Et3P)2-
9
(
Cl)Pd(Mes*) as a side product. Compound 4 could only
be characterized by NMR spectroscopy but reacted (eq
) with Pt(PEt3)4 to generate the bridging, dinuclear
3
1
2
1
2
η ,η -cyaphide complex Cl(Et3P)2Pt(µ-η ,η -CtP)Pt-
PEt3)2 (II), which was characterized by X-ray diffrac-
(
tion studies.
We describe in the present paper a high-yield prepa-
ration of complex II utilizing a one-step reaction from
the phosphavinyl complex trans-Cl(Et3P)2Pt[C(Cl)dPN-
(
SiMe3)2] (Ib), which has much different reactivity than
the analogous phosphavinyl complex trans-Cl(Et3P)2Pt-
C(Cl)dPMes*] (1).12 We also investigate functional-
Compound Ia was characterized by 31P and 31P{ H}
1
31
[
NMR spectra; compound Ib was characterized by
P
3
1
1
ization of the cyaphide ligand in complex II by reaction
of the accessible lone pair of electrons on the CtP
phosphorus atom. During the course of these studies,
we have isolated the first examples of trinuclear metal-
cyaphide compounds (A) that were formed by coordinat-
and P{ H} NMR spectra, elemental analysis, electro-
spray mass spectrometry, and X-ray diffraction studies.
3
1
The signals corresponding to P(x) in the P NMR
spectra of Ia and Ib were assigned by their character-
istic downfield chemical shifts of 225.1 and 222.3 ppm,
3
1
respectively, and by their proton-coupled P NMR
spectra, in which these signals do not show any proton
coupling, while the signals corresponding to the PEt3
groups are greatly broadened. The P(x) peak in Ia is
3
split into a doublet of doublets ( J P(x)P(a) ) 8.3 Hz,
3
J P(x)P(b) ) 33.0 Hz) by the two inequivalent PEt3 groups
2
and exhibits platinum satellites with J P(x)Pt ) 410 Hz.
3
The P(x) peak in Ib is split into a triplet ( J P(x)P(a) )
2
0.0 Hz) by the two equiv PEt3 groups and exhibits a
1
95
2
ing the CtP phosphorus atom in II to other transition
metal fragments. We have also found that the cyaphide
ligand in II can be easily converted to an alkyl iso-
cyaphide ligand by reaction with alkylating agents,
constituting the first examples of cyaphide-isocyaphide
conversions and demonstrating that isocyaphide ligands
with less bulky alkyl R-groups can be stabilized on
transition metals.
larger Pt-P coupling constant ( J P(x)Pt ) 676 Hz) than
in Ia . In Ia , the PEt3 ligand that is trans to the C(Cl)d
PN(SiMe3)2 group is assigned to P(b) at δ 10.1 ppm and
the cis PEt3 ligand is assigned to P(a) at δ 5.6 ppm based
on the larger coupling constant J P(x)P(b) ) 33.0 Hz
between P(x) in the C(Cl)dPN(SiMe3)2 group and the
3
3
1
trans PEt3 group P(b). These P NMR data are
analogous to those obtained for cis-Cl(Et3P)2Pt[C(Cl)d
1
2
3
3
PMes*] (δ(P(x)): 224.0 (dd, J P(x)P(a) ) 12.3 Hz, J P(x)P(b)
2
Resu lts a n d Discu ssion
) 46.3 Hz, J P(x)Pt ) 365.4 Hz) and trans-Cl(Et3P)2Pt-
3
[
C(Cl)dPMes*] (1) (δ(P(x)): 223.3 (t, J P(x)P(a) ) 25.2 Hz,
Syn th esis of tr a n s-Cl(Et3P )2P t[C(Cl)dP N(SiMe3)2]
2
J P(x)Pt ) 657.7 Hz), which indicates that the compounds
(
Ib). The reaction (eq 4) of Pt(PEt3)4 with Cl2CdPN-
are isostructural and that the N(SiMe3)2 group does not
impart dramatic differences in the bonding compared
with the Mes* group. However, to more thoroughly
(
12) J un, H.; Young, V. G., J r.; Angelici, R. J . Organometallics 1994,
1
3, 2444-53.

2
60 Organometallics, Vol. 18, No. 2, 1999
Konze et al.
compare the bonding properties in these complexes, the
structure of Ib was determined by X-ray diffraction
studies and compared with the previously determined
structure of compound 1.12
X-r a y Cr ysta l Str u ctu r e of tr a n s-Cl(Et3P )2P t-
[
C(Cl)dP N(SiMe3)2] (Ib). A thermal ellipsoid drawing
of Ib (Figure 1) shows that the complex is isostructural
with the previously characterized compound trans-Cl-
(Et3P)2Pt[C(Cl)dPMes*] (1). The platinum atom is in
a square-planar environment as defined by the two
PEt3, Cl, and [C(Cl)dPR] ligands; the sum of angles
around the platinum atom is 360.0°. The C(1)-P(1)
distance of 1.690(7) Å is the same as that (1.678(5) Å)
in compound 1 and the CdP distance (1.685(2) Å) in
the free phosphaalkene Cl2CdPN(SiMe3)2.13 The Pt-
C(1) distance in Ib (1.990(7) Å) is slightly shorter than
F igu r e 1. Thermal ellipsoid drawing of trans-Cl(Et
Pt[C(Cl)dPN(SiMe ] (Ib).
3 2
P) -
1
2
the corresponding distance (2.013 (4) Å) in 1.
The
3 2
)
nitrogen atom in Ib is in a trigonal planar environment,
and the P(1)-N(1)-Si(1)-Si(2) plane is almost orthogo-
nal (96.4°) to the plane defined by Pt, Cl(1), C(1), P(1),
and N(1). This orthogonality rules out any conjugative
effects from the nitrogen lone pair; in a series of X-ray-
determined structures of phosphaalkenes containing
NR2 groups on phosphorus, orthogonal NR2 groups were
found to show no conjugative effects with the CdP
(
SiMe3)2N-N(SiMe3)2, although this was not investi-
gated. The reaction of trans-Cl(Et3P)2Pt[C(Cl)dPMes*]
1) with Pt(PEt3)2Cl2 and 3 equiv of sodium benzophe-
(
none ketyl also resulted in the formation of II, but it
produced impurities that could not be separated. To
investigate the role of the reducing agent, a reaction was
attempted between Ib and Na/benzophenone ketyl
without any Pt(PEt3)2Cl2 present; no reaction was
apparent after 6 h. Also, if Pt(PEt3)2Cl2 is first com-
bined with Na/benzophenone ketyl followed by addition
1
4
double bond. If the [C(Cl)dPR] ligands in 1 and Ib
were significantly different, the bond lengths between
platinum and the trans ligands (Cl(2)) would be affected
by this difference. However, the Pt-Cl(2) length in Ib
31
of Ib, a P NMR spectrum shows that Ib is unreacted
(2.373(2) Å) is the same within error as that (2.377(2)
in solution. Evidently, both Ib and Pt(PEt3)2Cl2 must
be present during the addition of the reducing agent for
this reaction to occur. The reduction of Pt(PEt3)2Cl2 in
the presence of ethylene is known to produce Pt(PEt3)2-
(
Å) in 1. Thus, a comparison of the structures of 1 and
Ib indicates that the N(SiMe3)2 and Mes* groups show
similar structural effects in phosphavinyl complexes of
the type trans-Cl(Et3P)2Pt[C(Cl)dPR].
15
C2H4), and it has been reported that if a suitable
1
2
P r ep a r a tion of Cl(Et3P )2P t(µ-η ,η -CtP )P t(P Et3)2
II). The reaction (eq 5) of 1.05 equiv of trans-Cl(Et3P)2-
ligand is not present in solution, Pt(PEt3)2 fragments
tend to oligomerize into Pt(0) clusters. It is possible
(
16
Pt[C(Cl)dPN(SiMe3)2] (Ib) and 1 equiv of Pt(PEt3)2Cl2
with 3 equiv of sodium benzophenone ketyl in THF
forms the bridging, dinuclear cyaphide complex Cl-
that the Pt(PEt3)2 fragment that is generated in eq 5
coordinates to the CdP double bond of Ib and activates
the carbon-bound Cl toward reduction by a third equiv
of Na/benzophenone ketyl, while in the absence of Ib
the Pt(PEt3)2 oligomerizes and does not react with Ib.
Reactions similar to that in eq 5 were attempted
between Ib and Pt(PPh3)2Cl2, Pt(Pi-Pr3)2Cl2, Pt(PCy3)2-
Cl2, and Pt(depe)Cl2; in all cases, compound Ib remained
unreacted in solution, indicating that this reaction is
not general for other phosphines.
1
2
(Et3P)2Pt(µ-η ,η -CtP)Pt(PEt3)2 (II) in good yield (79%).
P r epar ation of Tr in u clear Metal-Cyaph ide Com -
p lexes. The cyaphide ligand that is coordinated to two
platinum centers in complex II contains a lone pair of
electrons on the CtP phosphorus atom that is a
potential site for further coordination. Accordingly, the
reactions (eq 6) of either 0.5 equiv of [Pt(Cl)2(PEt3)]2 or
This preparation is much simpler than that (eq 3)
originally reported. Furthermore, this reaction can be
done on a several gram scale and gives excellent yields
of complex II in pure, crystalline form.
To gain an understanding of how this reaction pro-
ceeds, several different stoichiometries of the reagents
were investigated, as was the order of addition. The
use of 3 equiv of the Na/benzophenone ketyl reducing
agent was found to be optimum, as more equiv caused
decomposition, while fewer resulted in incomplete reac-
tion, which suggests that the two chlorides from Pt-
(PEt3)2Cl2 and one chloride from Ib are removed as
NaCl. The N(SiMe3)2 group is possibly removed as
1
equiv of W(CO)5(THF) with II in THF at room
(
13) Antipin, M. Y.; Chernega, A. N.; Struchkov, Y. T. Phosphorus,
Sulfur Silicon Relat. Elem. 1993, 78, 289-96.
14) Chernega, A. N.; Romanenko, V. D. Zh. Obsch. Khim. 1992,
2, 1257-1263.
(
(15) Head, R. A. Inorg. Synth. 1990, 28, 132.
(16) Head, R. A. J . Chem. Soc., Dalton Trans. 1982, 1637.
6

1
2
-
η ,η -Bridging Cyaphide (CtP) Ligands
Organometallics, Vol. 18, No. 2, 1999 261
Ta ble 1. Com p a r ison of 31P NMR Da ta (THF ) for Cl(Et
P )
,aWh er e ML
Va )
P t(µ-η ,η -CtP )P t(P Et
1
2
3
2
3 2
) (II) w ith Th ose of th e
1
1
2
+
Com p lexes Cl(Et
3
P )
2
P t[µ-η ,η ,η -CtP {ML
n
}]P t(P Et
3
)
2
n
) P t(Cl) (P Et ) (III), W(CO) (IV), Me
2
3
5
(
δ P(x)
(ppm)
δ P(c)
(ppm)
δ P(b)
(ppm)
δ P(a)
(ppm)
3J (x)-(a)
(Hz)
2J (x)-(b)
(Hz)
2J (x)-(c)
(Hz)
2J (b)-(c)
(Hz)
1J Pt-(a)
(Hz)
1J Pt-(b)
(Hz)
1J Pt-(c)
(Hz)
cmpd
II
107.0
111.2
41.4
18.6
17.2
13.9
20.1
15.0
15.9
16.6
18.7
4.9
5.0
3.1
8.1
10.7
21.4
18.9
20.6
13.7
148.0
152.9
148.9
10.7
42.5
38.7
23.8
35.1
8.7
9.1
2936
2829
2818
2662
3155
3601
3568
3641
3619
2926
2917
2441
III
IV
Va
34.7
10.2
a
See eqs 5, 6 and Scheme 1 for atom labels.
temperature afford the first examples of trinuclear
to compound II also imparts a large change on the two-
bond coupling constant between P(x) and the trans-like
1
1
2
metal-cyaphide complexes Cl(Et3P)2Pt[µ-η ,η ,η -Ct
P{Pt(PEt3)(Cl)2}]Pt(PEt3)2 (III) and Cl(Et3P)2Pt[µ-
2
PEt3 ligand P(b); the value of J P(x)P(b) ) 13.7 Hz in II
1
1
2
2
η ,η ,η -CtP{W(CO)5}]Pt(PEt3)2 (IV), respectively. Com-
plex III forms immediately after the addition of
increases to J P(x)P(b) ) 148.0 Hz in III. This effect has
2
also been seen in η -phosphaalkyne complexes; in the
3
1
2
[
Pt(Cl)2(PEt3)]2 to II and a P NMR spectrum of the
complex [Pt(dppe)(η -t-BuCtP)], the coupling constant
reaction mixture showed practically quantitative con-
version to III with a small amount of Pt(PEt3)2Cl2
formed as a byproduct; complex III could not be isolated
in pure form, as it decomposes under vacuum to
unidentified materials, presumably through loss of PEt3.
In the reaction of W(CO)5(THF) with II, the formation
of complex IV is complete after 1 h, and a small amount
of W(CO)5(PEt3) forms as a byproduct that is easily
separated. These reactions are similar to those of the
between the CtP phosphorus and the trans-P atom is
28.1 Hz, but when a Cr(CO)5 fragment is coordinated
to the CtP phosphorus atom, this value increases to
1
7
177.5 Hz.
In fact, all of the couplings between P(x)
and the other phosphorus signals are increased upon
coordination of the Pt(PEt3)(Cl)2 group (see Table 1).
Evidently, the cyaphide phosphorus atom undergoes a
change in hybridization upon coordination to the metal
fragment, which gives the phosphorus more s-orbital
character in its bond with the metal.
2
2
η -coordinated phosphaalkyne complexes (R3P)2Pt(η -
2
Complex IV exhibits four distinct signals in its 31
P
R-CtP), in which η -coordination of the phosphaalkyne
to the platinum fragment enhances the coordinating
NMR spectrum; the peaks corresponding to P(a) at δ
3.1, P(b) at δ 16.6, and P(c) at δ 13.9 ppm were assigned
3
,17
ability of the lone pair of electrons on phosphorus.
Compounds III and IV were characterized by 31P and
P{ H} NMR spectroscopy, and the structure of com-
31
based on similar signals in the P NMR spectrum of II
3
1
1
and III, while the peak at δ 41.4 ppm was assigned to
3
1
plex IV was determined by X-ray diffraction studies.
The 31P NMR data for these compounds are compared
in Table 1 along with the starting cyaphide complex (II)
and the methyl isocyaphide complex (Va ), which is a
cationic complex of similar structure (see below). In all
of these complexes, the peaks corresponding to P(x) are
conveniently assigned by proton-coupled 31P NMR spec-
troscopy, in which the P(x) signals remain sharp, while
the PEt3 signals are broadened by coupling to the ethyl
protons. Complex III exhibits five distinct signals in
its 31P NMR spectrum; peaks corresponding to P(x) at
δ 111.2, P(a) at δ 5.0, P(b) at δ 15.9, and P(c) at δ 17.2
ppm were assigned on the basis of similar signals in
the 31P NMR spectrum of II, while the peak correspond-
ing to P(d) at δ 5.2 ppm was assigned to the PEt3 group
in the Pt(PEt3)(Cl)2 fragment that is coordinated to the
CtP phosphorus atom. The peak for P(x) in II is split
into a doublet of doublet of triplets, while the same peak
in III is now split into a doublet of doublet of doublet of
triplets; the extra splitting is from the PEt3 ligand on
P(x) based on a sharp proton-coupled P NMR signal
and the doublet of doublet of triplets splitting pattern.
The chemical shift of 41.4 ppm is 66 ppm upfield from
that of P(x) in compound II and is similar to the upfield
shift of 42 ppm that was measured upon coordination
of a W(CO)5 fragment to the CtP phosphorus atom in
2
2
the η -phosphaalkyne complex [Pt(dppe)(η -t-BuCt
1
7
P)]. The coordination of the W(CO)5 group to complex
3
1
31
II results in increased P- P coupling constants (see
Table 1) similar to those for III. The two-bond coupling
constant between P(x) and the trans-like PEt3 ligand
2
P(b) is again very large, J P(x)P(b) ) 152.9 Hz, and similar
2
to that ( J P(x)P(b) ) 148.0 Hz) in III. Only one set of
2
platinum satellites ( J P(x)Pt(1) ) 507 Hz) could be distin-
guished for P(x) in compound IV because of the com-
plexity of this signal; this coupling constant is larger
than that (255 Hz) in II, but still smaller than that (676
Hz) in Ib. Although no tungsten satellites could be
found for P(x), the signal for P(b) exhibited an unusually
3
large three-bond coupling to tungsten ( J WP(b) ) 150.8
2
the Pt(PEt3)(Cl)2 fragment ( J P(x)P(d) ) 472.3 Hz). This
Hz), most likely because of the enhanced coupling
between P(x) and P(b).
is a very large two-bond P-P coupling constant that is
indicative of a trans-orientation between P(d) and P(x),
1
1
2
X-r a y Cr ysta l Str u ctu r e of Cl(Et3P )2P t[µ-η ,η ,η -
CtP {W(CO)5}]P t(P Et3)2 (IV). A thermal ellipsoid
drawing of IV (Figure 2) shows that the complex
contains a W(CO)5 fragment attached to the CtP
phosphorus atom and has many structural features in
common with the X-ray-determined structure of complex
2
similar to the trans- J PP ) 557 found in the bridging
phosphaalkyne complex Mo2(CO)4(Cp)2{t-BuCP[Pt(PEt3)-
2
(
Cl)2]}18 and to the values of trans- J PP ) 462-483 Hz
measured in a series of trans-[PtCl2(PR3)(PR′3)] com-
plexes.19 The coordination of the Pt(PEt3)(Cl)2 fragment
9
II. Both of the platinum atoms in IV are in planar
(
17) Carmichael, D.; Al-Resayes, S. I.; Nixon, J . F. J . Organomet.
Chem. 1993, 453, 207-210.
18) Meidine, M.; Meir, C. J .; Morton, S.; Nixon, J . F. J . Organomet.
Chem. 1985, 297, 255.
19) Allen, F. H.; Sze, S. N. J . Chem. Soc. (A) 1971, 2054.
environments; the sum of angles around Pt(1) as defined
by C(1), P(2), P(3), and Cl(1) is 360.1°, while the sum of
angles around Pt(2) as defined by C(1), P(1), P(4), and
P(5) is 360.4°. The C(1)-P(1) distance (1.663(9) Å) in
(
(

2
62 Organometallics, Vol. 18, No. 2, 1999
Konze et al.
crystals could not be obtained for an X-ray diffraction
study as the compound only forms an oil. However, the
complex is likely isostructural with the previously
obtained semibridging isocyaphide complex (Cl)(Et3P)-
9
31
Pt(µ-CdPMes*)Pt(PEt3)2(Cl) (2) on the basis of its
P
1
3
31
NMR spectrum (Table 2) and the C- P coupling
constants obtained from the use of C-labeled MeI in
this reaction. Thus, the η ,η -cyaphide ligand in II is
converted to a semibridging isocyaphide ligand in Vc
with the formation of a Pt-Pt bond. This reaction has
some precedent in related isocyanide chemistry, as the
1
3
1
2
3 2
F igu r e 2. Thermal ellipsoid drawing of Cl(Et P) Pt[µ-
1
1
2
5 3 2
η ,η ,η -CtP{W(CO) }]Pt(PEt ) (IV).
IV is the same within error as that (1.666(6) Å) in II,
indicating that coordination of the W(CO)5 unit has not
dramatically changed the character of the cyaphide C-P
bond. This distance is similar to a C-P double-bond
-
conversion of coordinated cyanide (CtN) ligands to
isocyanide (CtNR) ligands with various alkylating
agents is a well-known synthetic route to isocyanide
complexes, although these reactions have been carried
2
0
distance (e.g., 1.67 Å in Ph(H)CdPMes*) and to the
2
C-P distance (1.67(2) Å) in the η -phosphaalkyne
24
out only on terminal cyanide complexes.
This new
2
21
complex [Pt(PPh3)2(η -t-BuCtP)] and is consistent
with back-bonding from Pt(2) into the π* orbital of the
CtP bond, affording some metallaphosphacyclopropene
character in this three-atom unit in IV. The Pt(1)-
C(1)-P(1) angle (145.2(6)°) is similar to that in II
synthetic route to an isocyaphide complex is much
different than the reaction (eq 1) of the phosphavinyl
complex trans-Cl(Et3P)2Pt[C(Cl)dPMes*] (1) with Pt-
(
PEt3)4 to generate the semibridging isocyaphide com-
9
plex (Cl)(Et3P)Pt(µ-CdPMes*)Pt(PEt3)2(Cl) (2) or the
reactions (eq 2) of [Cp2(CO)2Fe2(µ-CO)(µ-CSMe)] with
(
144.0(3)°), and the W(1)-P(1)-C(1) angle (136.1(3)°)
+
2
is also bent, indicating that P(1) is close to sp hybrid-
ization. This is also evident from the sum of the angles
RP(H)(SiMe3) and DBU to generate the bridging iso-
cyaphide complexes [Cp2(CO)2Fe2(µ-CO)(µ-CdPR)] (3);7
(355.3°) around P(1) involving W(1), Pt(2), and C(1),
both of these syntheses were limited by the use of bulky
aryl R-groups on the CtPR phosphorus atom. In
contrast, the reaction of II with MeI allows for the
formation of an isocyaphide with a sterically small
methyl group and could conceivably be a more general
route to diplatinum isocyaphide complexes. To test this,
the reaction in eq 7 was attempted with several different
alkyl and aryl halides (e.g., benzyl bromide, isopropyl
iodide, allyl bromide, o-iodo toluene, and 2,4,6-tri-tert-
butylbenzyl bromide) under the same reaction condi-
tions and stoichiometry as in the MeI reaction. The
reactions of both benzyl bromide (BnBr) and isopropyl
iodide (i-PrI) with II afforded similar isocyaphide prod-
ucts, (Cl)(Et3P)Pt(µ-CdPBn)Pt(PEt3)2(Br) (VI) and
which indicates that P(1) is nearly planar. The W(1)-
P(1) distance (2.531(3) Å) is very similar to the W-P
bond length (2.539(3) Å) in the bridging phosphaalkyne
complex Mo2(CO)4(Cp)2{t-BuCP[W(CO)5]}22 and is slightly
longer than typical W-P distances in structurally
characterized W(CO)4(PR3)2 complexes (e.g., 2.502 Å in
cis-W(CO)4(PMe3)2).23 The Pt(2)-C(1) distance (2.104(9)
Å) in IV is the same within experimental error as the
corresponding distance (2.083(5) Å) in II, and the Pt(1)-
C(1) distances (1.952(9) Å in IV and 1.950(6) Å in II)
are also the same within error. However, the Pt(2)-
P(1) distance (2.292(3) Å) in IV is shorter than the
corresponding distance (2.337(2) Å) in II.
1
2
Alk yla tion Rea ction s of Cl(Et3P )2P t(µ-η ,η -Ct
P )P t(P Et3)2 (II). The reaction (eq 7) of 3 equiv of MeI
(
Cl)(Et3P)Pt(µ-CdPi-Pr)Pt(PEt3)2(I) (VII), respectively,
31
as evidenced by P NMR spectroscopy (see Table 2).
However, the benzyl derivative could not be separated
from impurities that were present, and the i-Pr deriva-
tive was unstable and decomposed before the reaction
was complete. The reaction of allyl bromide with II
formed completely different products that could not be
isolated, while the aryl halides did not react with
compound II, even after stirring for several days at room
temperature.
1
2
with Cl(Et3P)2Pt(µ-η ,η -CtP)Pt(PEt3)2 (II) in THF for
2 h at 25 °C results in the formation of the methyl
isocyaphide complex (Cl)(Et3P)Pt(µ-CdPMe)Pt(PEt3)2(I)
Vc) with concomitant formation of the phosphonium
1
(
+
-
salt (MePEt3) I . This reaction entails the conversion
of a cyaphide (CtP) ligand to an isocyaphide (CtPMe)
-
ligand and substitution of a coordinated PEt3 ligand
+
-
(
lost as (MePEt3) I ) with an iodide ligand; thus, the
MeI acts both as a methylating agent and as a phos-
phine scavenger. Although complex Vc is stable in THF
solution at room temperature for several weeks, suitable
Complex Vc was characterized by electrospray mass
31
31
1
13
1
spectrometry and P, P{ H}, and C{ H) NMR spec-
31
troscopy. The P NMR spectrum of complex Vc shows
chemical shifts and coupling constants (Table 2) very
similar to those measured in the semibridging iso-
(
20) Appel, R.; Menzel, J .; Knoch, F.; Volz, P. Z. Z. Anorg. Allg.
Chem. 1986, 534, 100.
21) Burckett-St. Laurent, J . C. T. R.; Hitchcock, P. B.; Kroto, H.
W.; Nixon, J . F. J . Chem. Soc. Chem. Commun. 1981, 1141.
(
cyaphide complex (Cl)(Et3P)Pt(µ-CdPMes*)Pt(PEt3)2(Cl)
9
(
2) and is thus proposed to have the same structure.
(
(
22) Hitchcock, P. B. J . Chem. Soc., Chem. Commun. 1987, 658.
23) Elmes, P. S.; Gatehous, B. M.; West, B. O. J . Organomet. Chem.
1
974, 82, 235.
(24) Fehlhammer, W. P.; Frits, M. Chem. Rev. 1993, 93, 1243-1280.

1
2
-
η ,η -Bridging Cyaphide (CtP) Ligands
Organometallics, Vol. 18, No. 2, 1999 263
Ta ble 2. Com p a r ison of 31P NMR Da ta for (Cl)(Et
P )P t(µ-CdP Mes*)P t(P Et
3
3 2
) (Cl) (2),
(X) (Vc, R ) Me, X ) I; VI,
(
Cl)(P h
3
P )P t(µ-CO)P t(P P h (Cl) (4), a n d Com p lexes Cl(Et P )P t(µ-CtP R)P t(P Et
3
)
2
3
3 2
)
a
R ) Bn , X ) Br ; VII, R ) i-P r , X ) I)
δ P(x)
(ppm)
δ P(b)
(ppm)
δ P(a)
(ppm)
3J (x)-(b)
(Hz)
3J (x)-(a)
(Hz)
2J Pt2-(x)
(Hz)
2J Pt1-(x)
(Hz)
1J Pt2-(b)
(Hz)
2J Pt1-(b)
(Hz)
1J Pt1-(a)
(Hz)
2J Pt2-(a)
(Hz)
cmpd
2
4
Vc
VI
VII
151.3
22.8
30.2
21.5
22.8
25.9
19.6
21.74
8.7
13.3
12.9
35
23
321
110
4814
5440
5174
5223
5257
512
804
463
497
473
2428
2680
2339
2332
2367
67
59
43.5
47.0
46.4
155.4
172.1
200.3
15.3
13.8
15.2
12.1
11.7
12.1
565
593
538
232
228
232
a
See eq 7 for atom labels.
The 31P NMR spectrum of Vc exhibits three different
Sch em e 1
signals. The peak at δ 155.4 ppm, assigned to P(x), is
1
95
split into a doublet of triplets with two different
Pt
satellites, indicative of the unsymmetrical, semibridging
bonding mode of the CtPMe ligand. The doublet
2
(
J P(x)P(b) ) 15.3 Hz) arises from coupling to the single
3
PEt3 ligand (P(b)) on Pt(2), while the triplet ( J P(x)P(a) )
2.1 Hz) results from coupling to the two equiv PEt3
1
ligands (P(a)) on Pt(1). The larger coupling constant to
2
platinum ( J Pt(2)P(x) ) 564.7 Hz) is assigned to coupling
with the four-coordinate platinum Pt(2), while the
smaller Pt-P coupling constant ( J Pt(1)P(x) ) 231.9 Hz)
13C-labeled MeI. The 31
exhibited an extra doublet in the signal for P(x) from
coupling to the labeled methyl group with J P(x)C ) 48.9
Hz. This value is similar to the value of J PC ) 51.1
Hz found in the phosphonium salt (MePEt3) I product
of this reaction. Interestingly, the signal for P(b) also
P NMR spectrum of labeled Vc
2
is assigned to coupling with the five-coordinate platinum
atom Pt(1); these assignments are made on the basis of
the assignments in compound 2 and by the larger J PtP
coupling constants that are typically found in platinum
complexes with lower coordination numbers.2 From
these J PP coupling constants, the signal at δ 8.7 ppm is
assigned to P(a), while the signal at δ 21.52 is assigned
to P(b). Because the signal for P(a) is farther upfield
than the analogous peak in 2, while the peaks for P(b)
in Vc and 2 have quite similar chemical shifts, it is
assumed that the iodide ligand in Vc is on the platinum
1
1
+
-
5
4
exhibited a small coupling ( J P(x)C ) 10.6 Hz) to the
13
methyl group. The C NMR signal for the methyl group
at δ 10.5 was split into a doublet of doublets by P(x)
and P(b). This peak also exhibited a small Pt-C
3
coupling constant of J PtC ) 51.2 Hz, which is most
likely a coupling with Pt(2), which is bonded more
31
strongly to the CtPR group. The P NMR spectra of
(
Pt(1)) that contains two PEt3 groups (P(a)). One aspect
complexes VI and VII (Table 2) are quite similar to
those of Vc, and these compounds are proposed to be of
similar structure. These spectroscopic results, along
with comparisons with those of compounds 2 and 4,
strongly suggest that complexes Vc, VI, and VII contain
semibridging isocyaphide ligands.
3
1
of the P NMR spectrum of Vc that supports its
structural assignment as being similar to that of 2 is
the large difference in the one-bond J PtP coupling
constants in the signals for P(a) and P(b); for P(a) in
Vc, the value of J Pt(1)P(a) ) 2338.9 Hz is similar to those
found in trans-Pt(PEt3)2X2 complexes; while for P(b),
1
2
5
Mech a n istic Stu d ies of th e F or m a tion of (Cl)-
1
the value of J Pt(2)P(b) ) 5173.7 Hz is very large and more
(
Et3P )P t(µ-CdP Me)P t(P Et3)2(I) (Vc). A likely path-
similar to those found in three-coordinate Pt(0) com-
plexes.25 This difference in the J PtP coupling constants
is greater in Vc than in compound 2 and has been
discussed previously in the analogous semibridging
carbonyl complex (Cl)(Ph3P)Pt(µ-CO)Pt(PPh3)2(Cl) (4),
which is very similar in structure to Vc and 2, but with
PPh3 instead of PEt3 ligands and a semibridging CO
way (Scheme 1) for the formation of complex Vc from
complex II is the initial methylation of the CtP
1
2
phosphorus atom to generate a cationic η ,η -iso-
cyaphide intermediate (Va ). The iodide anion then
attacks at Pt(2) to generate the bridging isocyaphide
intermediate Vb, which loses a PEt3 group and forms a
metal-metal bond to generate the product Vc. An
intermediate similar to Vb was postulated in the
reaction (eq 1) of the phosphavinyl complex trans-
Cl(Et3P)2Pt[C(Cl)dPMes*] (1) with Pt(PEt3)4 to gener-
2
6,27
ligand in place of the CtPR ligands.
Complex 4
1
exhibits a value of J PtP ) 2680 Hz for the two equiv
PPh3 groups (P(a)) on the five-coordinate platinum and
a value of J PtP ) 5440 Hz for the PPh3 group (P(b)) on
1
ate the semibridging isocyaphide complex (Cl)(Et3P)Pt-
the four-coordinate platinum (see Table 2 for further
comparisons). This difference was rationalized by sug-
gesting some degree of mixed valence character between
the two platinum atoms.26 To further verify that the
methyl group is attached to the phosphorus atom in
complex Vc, the reaction (eq 7) was carried out using
9
(µ-CdPMes*)Pt(PEt3)2(Cl) (2). In an attempt to verify
1
2
this pathway by isolation of the cationic η ,η -iso-
cyaphide intermediate (Va ), complex II was reacted
with 1 equiv of MeI in the presence of 2 equiv of NaBPh4
in THF at room temperature. The color of the solution
turned to a very deep ruby red color after 1 h, and a
31
P
NMR spectrum (see below) showed a new complex that
(
25) Pidcock, A.; Nixon, J . F. Annu. Rev. NMR Spectrosc. 1969, 2,
45.
26) Goodfellow, R. J .; Herbert, I. R.; Orpen, A. G. J . Chem. Soc.,
Chem. Commun. 1983, 1386.
27) Bender, R.; Braunstein, P.; Tiripicchio, A.; Tiripicchio-Camellini,
M. J . Chem. Soc., Chem. Commun. 1984, 42.
3
matches the structure drawn for Va where the iodide
(
-
anion has been replaced with (BPh4 ). This complex
was then isolated in reasonably pure form by filtering
the solution and adding hexanes to form an oil of mainly
(

2
64 Organometallics, Vol. 18, No. 2, 1999
Konze et al.
Va . When a 10-fold excess of NaI was added to a
solution of Va in THF, the color changed from deep red
to light orange in 10 min, and a 31P NMR spectrum
showed that this complex was completely converted to
the semibridging isocyaphide complex Vc, which strongly
suggests that Va is an intermediate that forms before
Vc in the reaction of MeI with complex II. In a separate
experiment, complex II was reacted with MeO3SCF3 in
THF; the color turned to deep red within a few minutes,
coupling to the labeled methyl group. The 13C NMR
spectrum also displayed a peak for the methyl group at
δ 8.7 ppm that was split into a doublet of doublet of
doublets by these three phosphorus atoms. These
results are entirely consistent with the proposed struc-
ture of Va and indicate that the attachment of a
+
W(CO)5, Pt(Cl)2(PEt3), or Me group to the cyaphide
phosphorus atom in complex II gives products with very
3
1
similar P NMR spectra and structures.
3
1
and a P NMR spectrum of the solution again showed
complex Va where a triflate anion is substituted for the
iodide anion. Reaction of this solution with a 10-fold
excess of NaI afforded complex Vc, providing further
evidence for the pathway outlined in Scheme 1. Al-
Su m m a r y
The new structurally characterized, phosphavinyl
complex trans-Cl(Et3P)2Pt[C(Cl)dPN(SiMe3)2] (Ib) re-
acts (eq 5) with Pt(PEt3)2Cl2 and Na/benzophenone ketyl
though there was no evidence in the 31P NMR spectra
1
2
to form the known η ,η -bridged cyaphide complex Cl-
for other intermediates, Vb is a likely intermediate that
1
2
1
2
(Et3P)2Pt(µ-η ,η -CtP)Pt(PEt3)2 (II) but this route is
explains the rearrangement of the η ,η -isocyaphide
ligand in Va to the semibridging isocyaphide ligand in
much simpler and gives higher yields than previously
9
reported (eq 3). Lewis acid adducts at the electron pair
Vc. In contrast to Vc, which contains a Pt-Pt bond,
-
the 31P NMR spectrum (see below) of Va suggests that
on the phosphorus of the cyaphide (CtP) ligand in
complex II are obtained by reaction with 0.5 equiv of
there is no Pt-Pt bond in this cationic isocyaphide
complex. Clearly, compound Va does not contain a
semibridging isocyaphide similar to that in Vc, and it
is not clear why substitution of a PEt3 group in Va by
an iodide anion causes this rearrangement to take place.
[Pt(Cl)2(PEt3)]2 or with 1 equiv of W(CO)5(THF) to
generate (eq 6) the first examples of trinuclear metal
1
1
2
cyaphide complexes Cl(Et3P)2Pt[µ-η , η ,η -CtP{Pt-
1
1
2
(
PEt3)(Cl)2}]Pt(PEt3)2 (III) and Cl(Et3P)2Pt[µ-η ,η ,η -
CtP{W(CO)5}]Pt(PEt3)2 (IV), respectively. The phos-
1
2
Complex Va is the first to exhibit an η ,η -bridging
-
phorus of the cyaphide (CtP) ligand in complex II is
isocyaphide ligand.
also alkylated (eq 7) by MeI to give the semibridging
methyl isocyaphide (CtPMe) complex (Cl)(Et3P)Pt(µ-
CdPMe)Pt(PEt3)2(I) (Vc). This transformation (Scheme
Although complex Va could not be isolated in pure
form, the 31P NMR spectrum is characteristic of an η ,η -
1
2
bridging isocyaphide structure and shows features
1
2
1
) was demonstrated to involve a cationic η ,η -bridging
(
Table 1) very similar to those in the spectra of the
1
2
isocyaphide intermediate [(Cl)(Et3P)2Pt(µ-η ,η -CtPMe)-
Pt(PEt3)2](I) (Va ), which was isolated as the triflate salt
when complex II was reacted with MeO3SCF3. The
1
1
2
η ,η ,η -bridging trimetallic cyaphide complexes with a
Pt(Cl)2(PEt3) fragment (III) and a W(CO)5 fragment
(
IV) on the cyaphide phosphorus atom. The signal at
1
2
µ-η ,η -CtPMe ligand in compound Va represents a new
bonding mode for isocyaphide ligands, and the methyl-
ation reaction of compound II to form Vc provides a new
method of forming semibridging isocyaphide complexes.
Compound Vc is also the first example of a complex to
contain an isocyaphide ligand with a nonbulky alkyl
group, demonstrating that steric protection of the reac-
tive CtP bond by bulky R-groups is not necessary for
the stabilization of transition metal-coordinated iso-
cyaphide ligands.
δ 34.7 ppm in Va , assigned to P(x), is shifted 120 ppm
upfield from the corresponding P(x) peak in Vc; this
1
2
shift is most consistent with an η ,η -bridged species.
The chemical shift is quite similar to that (δ 41.4 ppm)
in the tungsten-coordinated cyaphide complex IV, which
differs only in that it is neutral and contains a W(CO)5
group in place of the Me group on Va . Also supporting
the proposed structure is the fact that the splitting
patterns and coupling constants in Va , III, and IV are
all quite similar (Table 1). The coupling constants
between P(x) and the PEt3 groups again are larger than
Exp er im en ta l Section
1
2
those in the η ,η -cyaphide complex (II), with the most
2
dramatic effect again being a large coupling ( J P(x)P(b) )
Gen er a l P r oced u r e. All manipulations were carried out
under a dry, oxygen-free argon atmosphere, using standard
Schlenk techniques. All solvents employed were reagent grade
and dried by refluxing over appropriate drying agents under
1
48.9 Hz) between P(x) and P(b). This is very similar
2
2
to the J P(x)P(b) values found in III ( J P(x)P(b) ) 148.0 Hz)
and IV ( J P(x)P(b) ) 152.9 Hz). The
2
195
31
Pt- P coupling
nitrogen. Tetrahydrofuran (THF) and diethyl ether (Et
were distilled over sodium benzophenone ketyl, while hexanes
and dichloromethane (CH Cl ) were distilled over CaH
The P{ H} and P NMR spectra were recorded on a
2
O)
constants found in Va are also similar to those found
in III and IV (Table 1) and provide further evidence for
2
2
2
.
1
95
31
the proposed structure. Since there is no
Pt- P
31
1
31
coupling of P(a) with Pt(2) or between P(b) and P(c) with
Pt(1), the existence of a Pt-Pt bond in Va is doubtful;
in Vc and 2, which contain Pt-Pt bonds, these couplings
to the platinum atom of the adjacent metal fragment
were significant (43-512 Hz). To further verify that
the methyl group is attached to the cyaphide phospho-
rus atom, complex Va was prepared by reacting complex
3 4
Bruker AC 200 MHz spectrometer using 85% H PO (δ 0.00
ppm) as the external standard. The 13C{ H} and C NMR
1
13
spectra were recorded on a Bruker DRX 400 MHz spectrometer
using CDCl
spectra were recorded on a Finnigan TSQ 700 spectrometer
using CH Cl as solvent. Elemental analyses were performed
by National Chemical Consulting, Inc., Tenafly, NJ . The
3
as the internal standard. Electrospray mass
2
2
2
8
29
30
compounds Pt(PEt
Pt(PR ) Cl ,
3 2 2
3
)
4
,
Cl
2 3 2 2 3 2
CdPN(SiMe ) , [Pt(Cl) (PEt )] ,
1
3
II with C-labeled MeI in the presence of NaBPh4. The
3
1
and Na/benzophenone ketyl were prepared by
3
1
P NMR spectrum of this labeled complex exhibited
1
3
additional doublets [P(x) ( J P(x)C ) 71.5 Hz), P(b) ( J P(b)C
)
(28) Yoshida, T.; Matsuda, T.; Otsuka, S. Inorg. Synth. 1979, 19,
3
8.4 Hz) and P(c) ( J P(c)C ) 12.6 Hz)] as a result of
110.

1
2
-
η ,η -Bridging Cyaphide (CtP) Ligands
Organometallics, Vol. 18, No. 2, 1999 265
literature methods. Phosphine ligands were purchased from
Strem and used without further purification, with the excep-
portions of hexanes at -78 °C, and drying under vacuum to
give II (1.05 g, 79%). Compound II was characterized by
3
1
tion of PPh
iodide (MeI) and methyl triflate (MeO
from Aldrich and used without further purification. W(CO)
3
, which was recrystallized from MeOH. Methyl
comparison of its P NMR spectrum with that of an authentic
SCF ) were purchased
3
sample. 31P{ H} NMR (THF) (see eq 5 for atom labels): δ(P(x))
1
3
2
2
3
5
-
107.0 (ddt, J P(x)P(b) ) 13.7 Hz, J P(x)P(c) ) 10.7 Hz, J P(x)P(a) )
2 1
(
THF) was prepared by photolysis of W(CO)
6
in THF for 6 h
10.7 Hz, J Pt(1)P(x) ) 255 Hz, J Pt(2)P(x) ) 58 Hz), δ(P(c)) 18.6 (dd,
2 1
3
2
P(c)P(b) ) 35.1 Hz, 2
at 20 °C.
J
J
P(c)P(x) ) 10.7 Hz,
J
Pt(2)P(c) ) 3619 Hz,
3J Pt(1)P(c) ) 137 Hz), δ(P(b)) 15.0 (ddt, J P(b)P(c) ) 35.1 Hz, J P(b)P(x)
2
2
P r ep a r a t ion of tr a n s-Cl(E t
Ib) th r ou gh In ter m ed ia te cis-Cl(Et
SiMe ] (Ia ). To a cooled (-50 °C) solution of Pt(PEt
CdPN(SiMe
0.616 g, 2.25 mmol). A 31P{ H} NMR spectrum taken 10 min
3
P )
2
P t [C(Cl)dP N(SiMe
P ) P t[C(Cl)dP N-
(1.50
3
)
2
]
4
1
(
(
3
2
) 13.7 Hz, J P(b)P(a) ) 4.5 Hz, J Pt(2)P(b) ) 3155 Hz), δ(P(a)) 4.9
3 2 1
)
2
3
)
4
(dd, J P(a)P(x) ) 10.7 Hz, J P(a)P(b) ) 4.5 Hz, J Pt(1)P(a) ) 2936 Hz).
3
1
1
2
g, 2.25 mmol) in hexanes (20 mL) was added Cl
2
3
)
2
P r ep a r a t ion of Cl(E t
(Cl) }]P t(P Et (III). To a dry mixture of Cl(Et
CtP)Pt(PEt (II) (0.100 g, 0.106 mmol) and [Pt(Cl)
3
P )
2
3
P t [µ-η ,η ,η -CtP {P t (P E t )-
1
1
2
(
2
3
)
2
3
P)
2
Pt(µ-η ,η -
(PEt )]
after the addition (-50 °C) showed complete conversion to Ia .
3
)
2
2
3
2
After the solution had warmed to 0 °C over the course of 30
(0.0408 g, 0.0531 mmol) at room temperature was added 10
mL of THF with stirring. The color turned from dark orange
to light orange immediately. A 31P NMR spectrum taken after
5 min of stirring showed quantitative formation of III, with a
3
1
1
min, a P{ H} NMR spectrum showed that compound Ia had
completely isomerized to Ib. The almost colorless solution was
warmed to room temperature over the course of 10 min, and
the solvent was removed under vacuum. The residue was
treated with 20 mL of hexanes and filtered, and the filtrate
was concentrated to 10 mL. A white precipitate formed, which
3 2 2
small amount of Pt(PEt ) Cl present (characterized by com-
parison of its 31P NMR spectrum with that of an authentic
sample). The volume of the solvent was reduced to 2 mL, and
was found to be Pt(PEt
3
)
2
Cl
2
by comparison of its 31P NMR
3 2 2
5 mL of hexanes was added to precipitate the Pt(PEt ) Cl
spectrum with that of an authentic sample. The precipitate
was filtered off, and the filtrate was concentrated to 5 mL
under vacuum. The light orange/brown solution was cooled
slowly to -78 °C for 3 days, after which time large, light yellow
crystals had formed. The crystals were isolated by cannulating
off the mother liquor, washing with 2 × 5 mL portions of
hexanes at -78 °C, and drying under vacuum to give air-stable
impurity. The solution was filtered, and a 31P NMR spectrum
of the filtrate showed very pure III. Compound III is stable
in hexanes for several days at -30 °C, but decomposes at room
temperature in about 1 day. Compound III could not be
purified for elemental analysis, as it decomposed to unidenti-
3
1
fied products under vacuum, and was characterized by
NMR spectroscopy. P{ H} NMR (THF) (see eq 6 for atom
P
3
1
1
3
1
1
2
2
Ib (1.24 g, 78%). P{ H} NMR (hexanes) (see eq 4 for atom
labels): δ(P(x)) 111.2 (dddt,
J
P(x)P(d) ) 472.3 Hz,
J
P(x)P(b)
)
3
2
3
labels) for Ia , -50 °C: δ(P(x)) 225.1 (dd, J P(x)P(b) ) 33.0 Hz,
148.0 Hz, J P(x)P(c) ) 42.5 Hz, J P(x)P(a) ) 21.4 Hz), δ(P(c)) 17.2
3
2
3
2
4
2
J
P(x)P(a) ) 8.3 Hz, J PtP(x) ) 410.0 Hz), δ(P(b)) 10.1 (dd, J P(b)P(x)
(ddd, J P(c)P(x) ) 42.5 Hz, J P(c)P(d) ) 22.0 Hz, J P(c)P(b) ) 8.7 Hz,
2
1
1
4
2
)
(
33.0 Hz, J P(b)P(a) ) 16.2 Hz, J PtP(b) ) 1908 Hz), δ(P(a)) 5.6
dd, J P(a)P(b) ) 16.2 Hz, J P(a)P(x) ) 8.3 Hz, J PtP(a) ) 3874 Hz).
J
J
Pt(2)P(c) ) 2926 Hz), δ(P(b)) 15.9 (ddd,
J
P(b)P(x) ) 148.0 Hz,
Pt(2)P(b) ) 3601 Hz),
2
3
1
2
P(b)P(c) ) 8.7 Hz, 1
P(b)P(d) ) 56.0 Hz,
J
J
3
2
δ(P(d)) 5.21 (ddd, 2J P(d)P(x) ) 472.3 Hz, 4J P(d)P(b) ) 56.0 Hz,
For Ib, 25 °C: δ(P(x)) 222.3 (t, J P(x)P(a) ) 20.0 Hz, J PtP(x)
6
Hz). Electrospray MS (for Ib): m/e 705 (M ). Anal. Calcd
)
3
1
4
1
3
76.0 Hz), δ(P(a)) 14.1 (d, J P(a)P(x) ) 20.0 Hz, J PtP(a) ) 2680
J P(d)P(c) ) 22.0 Hz, J Pt(3)P(d) ) 3020 Hz), δ(P(a)) 5.0 (d, J P(a)P(x)
1 195 31
+
) 21.4 Hz,
J
Pt(1)P(a) ) 2829 Hz). (The
Pt- P coupling
for C19
H
48Cl
2
N
1
P
3
Pt
1
Si
2
(Ib): C, 32.34; H, 6.86; N, 1.98.
constants in the P(x) signal were not possible to determine
because of the complexity of the splittings.)
Found: C, 31.25; H, 6.62; N, 1.87. Although the carbon
analyses were consistently low for repeated analyses of Ib, the
composition of the compound is strongly supported by the NMR
and mass spectra, as well as the X-ray diffraction study.
1
1
2
P r ep a r a tion of Cl(Et P ) P t[µ-η
3
2
,η
5
,η -CtP {W(CO) }]P t-
1
2
(P Et3)2 (IV). To a solution of Cl(Et P) Pt(µ-η
3
2
,η
-CtP)Pt-
(PEt ) (II) (0.500 g, 0.531 mmol) in THF (10 mL) at room
3
2
1
2
P r ep a r a tion of Cl(Et
To a dry mixture of trans-Cl(Et
1.00 g, 1.42 mmol) and Pt(PEt
3
P )
2
P t(µ-η ,η -CtP )P t(P Et
P) Pt[C(Cl)dPN(SiMe
Cl (0.747 g, 1.49 mmol) at
3
)
2
(II).
] (Ib)
5
temperature was added W(CO) (THF) (0.531 mmol) in THF
3
2
3
)
2
(20 mL) with stirring. The color of the solution turned from
dark orange to dark red after 1 h of stirring. The solvent
volume was reduced to ca. 3 mL under vacuum, and 15 mL of
hexanes was added. The flask was cooled to -30 °C for 1 h
with formation of an oily solid impurity. The solution was
filtered, and the filtrate was reduced in volume to 5 mL and
then cooled slowly to -78 °C for 3 days, after which time light
orange crystals of IV had formed. The crystals were isolated
by cannulating off the mother liquor, washing them with 2 ×
5 mL portions of hexanes at -78 °C, and drying under vacuum
(
3
)
2
2
room temperature was added dropwise with stirring 20.8 mL
of a solution of 0.204 M Na/benzophenone ketyl in THF (4.25
mmol) (the molarity of the Na/benzophenone solution was
determined by quenching a measured amount with water and
titrating with standardized HCl solution). The addition was
done at a rate that was determined by the color change; as
the color turned blue, addition was halted until the color
changed back to orange. The total time of the addition was
ca. 45 min, after which time the color of the solution was dark
red with a large amount of NaCl precipitate. The solution was
filtered through Celite, and the solvent was removed from the
filtrate under vacuum. Extended drying under vacuum,
especially with heating, was found to cause decomposition. The
dark red residue was treated with hexanes (30 mL), the
mixture was filtered through Celite, and the filtrate was
3
1
at -50 °C to give IV (0.375 g, 56%) that was pure by P NMR
spectroscopy. Further drying under vacuum at room temper-
ature resulted in partial decomposition to an oily solid, which
prevented proper elemental analysis. 31P{ H} NMR (THF) (see
1
2
eq 6 for atom labels): δ(P(x)) 41.4 (ddt, J P(x)P(b) ) 152.9 Hz,
2
3
1
J
P(x)P(c) ) 38.7 Hz,
J
P(x)P(a) ) 18.9 Hz,
J
Pt(1)P(x) ) 507 Hz),
2
2
1
δ(P(c)) 13.9 (dd, J P(c)P(x) ) 38.7 Hz, J P(c)P(b) ) 9.1 Hz, J Pt(2)P(c)
3
1
2
2
reduced in volume to 10 mL. A P NMR spectrum of this
solution showed II; benzophenone was present as the only
impurity. The solution was cooled slowly to -78 °C and kept
at this temperature for 1 week, after which time dark red
crystals of II had formed. The crystals were isolated by
cannulating off the mother liquor, washing with 2 × 5 mL
) 2917 Hz), δ(P(b)) 16.6 (dd, J P(b)P(x) ) 152.9 Hz, J P(b)P(c) )
3 1
9.1 Hz, J WP(b) ) 150.8 Hz, J Pt(2)P(b) ) 3568 Hz), δ(P(a)) 3.1 (d,
3
1
J
P(a)P(x) ) 18.9 Hz, J Pt(1)P(a) ) 2818 Hz).
P r ep a r a tion of [(Cl)(Et P )P t(µ-CdP Me)P t(P Et ) (I)]
3
3 2
1
2
(Vc). To a stirred solution of Cl(Et P) Pt(µ-η
3
2
,η
-CtP)Pt-
(PEt ) (II) (0.500 g, 0.531 mmol) in THF (10 mL) at room
3
2
temperature was added MeI (0.226 g, 1.59 mmol) all at once.
(
29) Prishchenko, A. A.; Gromov, A. V.; Luzikov, Y. N.; Borisenko,
A. A.; Lazhko, E. I.; Klaus, K.; Lutsenko, I. F. Zh. Obshch. Khim. 1985,
4, 1520.
After stirring for 12 h at 25 °C, the color had changed from
-
3
dark orange to light orange and a precipitate of [MePEt ]I
5
31
had formed (characterized by comparison of its P NMR with
an authentic sample). The solution was filtered, the solvent
was removed from the filtrate under vacuum, and the residue
(
(
(
30) Baratta, W.; Pregosin, P. S. Inorg. Chim. Acta 1993, 209, 85.
31) Hartley, F. R. Organometal. Chem. Rev. A 1970, 6, 119-137.
32) Orama, O. J . Organomet. Chem. 1986, 314, 273.

2
66 Organometallics, Vol. 18, No. 2, 1999
Konze et al.
3 2
) (Ib) a n d
Ta ble 3. Cr ysta l a n d Da ta Collection P a r a m eter s for tr a n s-Cl(Et
3
P )
2
P t[C(Cl)dP N(SiMe
1
1
2
Cl(Et
3
P )
2
P t[µ-η ,η ,η -CtP {W(CO)
}]P t(P Et ) (IV)
5 3 2
Ib
IV
formula
space group
a, Å
C19H48Cl2NP3Si2Pt
Pbca
11.802(2)
C30H60ClO5P5Pt2W
P21/n
11.0994(2)
b, Å
15.060(3)
33.5717(2)
c, Å
35.060(3)
12.4301(1)
R, deg
â, deg
γ, deg
90
90
90
90
111.659(1)
90
4304.76(9)
3
V, Å
6231.7(16)
Z
8
4
3
dcalc, g/cm
1.504
1.952
crystal size, mm
µ, mm
data collection instrument
0.377 × 0.377 × 0.125
0.4 × 0.12 × 0.12
-
1
12.244
9.429
Siemens P4RA
Siemens SMART
radiation (monochromated in incident beam)
temp, K
Cu KR (λ ) 1.541 78 Å)
213(2)
Mo KR (λ ) 0.710 73 Å)
173(2)
scan method
data collection range
no. of data collected
2θ-θ
4.0-115.0; θ, deg
7857
Area Detector, ω-frames
1.21-25.07; 2θ, deg
21 054
no. of unique data total with I g 2σ(I)
no. of params refined
3207
278
5738
390
trans factors; max/min
0.2836/0.0379
0.0368
0.0442
1.33
1.000/0.433
0.0476
0.0942
1.023
1.462
a
R
(I > 2σ(I))
a
Rw (I > 2σ(I))
quality of fit indicator
largest peak, e/Å
c
3
1.57
a
R ) ∑||Fo| - |Fc||/∑|Fo|. Rw ) (∑w(|Fo| - |Fc|) /∑w|Fo| ) ; w ) 1/σ (|Fo|). Quality-of-fit ) [∑w(|Fo| - |Fc|) /(Nobs - Nparams)]1/2.
b
2
2
1/2
2
c
2
-
was treated with 25 mL of hexanes. After reducing the solvent
under vacuum to 5 mL, the solution was filtered and cooled
slowly to -78 °C for 2 days to form an oil of Vc that was pure
followed by 3 × 5 mL portions of Et
2
O to afford the BPh
4
salt
of Va (crude yield 0.103 g, 38%). A similar preparation was
carried out using 13C-labeled MeI in order to obtain C- P
coupling constants. P{ H} NMR (THF) (see Scheme 1 for
13
31
3
1
31
1
by P NMR spectroscopic studies (yield 0.386 g, 75%).
A
1
3
2
2
similar preparation was carried out using C-labeled MeI in
atom labels): δ(P(x)) 34.7 (ddt, J
) 148.9 Hz, J
)
P(x)P(b)
P(x)P(c)
1
3
31
31
1
3
2
order to obtain C- P coupling constants.
P{ H} NMR
23.8 Hz, J
) 20.6 Hz), δ(P(c)) 20.1 (dd, J
) 23.8
P(x)P(a)
P(c)P(x)
3
2
1
(
THF) (see eq 7 for atom labels): δ(P(x)) 155.4 (dt, J P(x)P(b)
)
)
Hz, J
) 10.2 Hz, J
) 2441 Hz), δ(P(b)) 18.7 (ddt,
P(c)P(b)
Pt(2)P(c)
3
2
2
2
J P(b)P(x) ) 148.9 Hz, 2J P(b)P(c) ) 10.2 Hz, J P(b)P(a) ) 5.7 Hz,
4
1
2
5.3 Hz, J P(x)P(a) ) 12.1 Hz, J Pt(2)P(x) ) 564.7 Hz, J Pt(1)P(x)
3
1
1
3
4
31.9 Hz), δ(P(b)) 21.5 (d, J P(b)P(x) ) 15.3 Hz, J Pt(2)P(b) ) 5173.7
J
) 3640 Hz), δ(P(a)) 8.1 (dd, J
P(a)P(x)
) 20.6 Hz, J
195 31
Pt(2)P(b)
P(a)P(b)
2
3
) 5.7 Hz, 1J Pt(1)P(a) ) 2661 Hz). (The
constants in the P(x) signal were not possible to determine
Hz, J Pt(1)P(b) ) 463.4 Hz), δ(P(a)) 8.7 (d, J P(a)P(x) ) 12.1 Hz,
Pt- P coupling
1
Pt(1)P(a) ) 2338.9 Hz, 2
13
1
J
C
J
J
Pt(2)P(a) ) 43.5 Hz).
C{ H} NMR
1
4
(
6
D
6
): δ(CH
3
P) 10.5 (dd, J CP(x) ) 48.9 Hz, J CP(b) ) 10.6 Hz,
CPt(2) ) 51.2 Hz). Electrospray MS (for Vc): m/e 963 (M
13
1
because of the complexity of the splittings).
C{ H} NMR
P) 8.7 (ddd, J CP(x) ) 71.5 Hz, J CP(c) ) 12.6 Hz,
3
+
-
1
3
(
THF): δ(CH
3
H).
F or m a tion of [Cl(Et
Va ). Meth od A. To a stirred solution of Cl(Et
CtP)Pt(PEt (II) (0.350 g, 0.372 mmol) in THF (15 mL) at
room temperature was added MeO SCF (0.0610 g, 0.372
3
J
CP(b) ) 8.4 Hz).
1
2
+
3
P )
2
P t(µ-η ,η -CtP Me)P t(P Et
3
1
)
2
]
1
2
]+
Con ver sion of [Cl(Et
3
P )
2
3 2
P t(µ-η ,η -CtP Me)P t(P Et )
2
(
3 2
P) Pt(µ-η ,η -
(
Va ) t o [(Cl)(E t P )P t (µ-CdP Me)P t (P E t
3
3
)
2
(I)] (Vc). To a
3 2
)
stirred solution of Va (0.100 g, 0.0784 mmol) in THF (20 mL)
at room temperature, prepared as in method B above, was
added NaI (0.118 g, 0.784 mmol) as a solid. After stirring for
3
3
mmol) all at once. After stirring for 5 min, the color of the
solution changed from dark orange to dark, ruby red. The
volume of the solution was reduced to 2 mL, and 15 mL
hexanes was added to form a dark red oil that separated from
solution. The remaining light red solution was removed from
the oil with a cannula, and the oil was washed with 3 × 8 mL
portions of hexanes to afford the triflate salt of Va (crude yield
1
0 min, the color had changed from dark red to light orange.
The solvent was removed under vacuum, and the residue was
taken up in 20 mL of hexanes. The solution was filtered over
Celite, and the filtrate was shown to contain mainly Vc by a
P NMR spectrum, but it could not be isolated pure, as it
contained impurities that likely resulted from decomposition
3
1
3
1
0
.279 g, 68%).
A
P NMR spectrum showed that this oil
of Va before or during the reaction.
contained a small amount of impurities, which were more
prevalent after 1 day. Complete decomposition was evident
X-r a y Cr ysta llogr a p h ic Stu d y of tr a n s-Cl(Et
3 2
P ) P t-
3
1
[C(Cl)dP N(SiMe ) ] (Ib). Diffraction-quality crystals of Ib
after 1 week at room temperature. (The P NMR spectrum
3 2
-
were obtained by recrystallization from hexanes at -78 °C.
Data collection and reduction information are given in Table
3. A light orange crystal of Ib was mounted on a glass fiber
for data collection. Cell constants were determined from
reflections found in a rotation photograph. High-angle cell
constants were determined from a subset of intense reflections
in the range 35.0-50.0° 2θ. The data were corrected for
Lorentz and polarization effects. A correction based on
nonlinear decay in the three standard reflections was applied
to the data. An absorption correction based on measured
crystal faces was applied. The space group Pbca was unam-
biguously determined by systematic absences and intensity
statistics.33 A successful direct methods solution was calcu-
was the same as that for the BPh
Meth od B. To a stirred solution of Cl(Et
P)Pt(PEt (II) (0.200 g, 0.212 mmol) and NaBPh
.425 mmol) in THF (10 mL) at room temperature was added
4
salt below.)
P) Pt(µ-η ,η -Ct
(0.145 g,
1
2
3
2
3
)
2
4
0
MeI (0.302 g, 0.212 mmol) all at once. The color of the solution
turned from dark orange to very dark red after 3 h of stirring.
The solution was treated with 10 mL of hexanes, and a large
amount of oily precipitate formed. The solution was filtered,
and the solvent in the filtrate was removed under vacuum.
The residue was dissolved in 2 mL of THF, and 15 mL of
hexanes was added to form a dark red oil that separated from
the solution. The oil was isolated by cannulating off the
solution and washing with 3 × 8 mL portions of hexanes

1
2
-
η ,η -Bridging Cyaphide (CtP) Ligands
Organometallics, Vol. 18, No. 2, 1999 267
Ta ble 4. Selected Bon d Dista n ces (Å) a n d An gles
Ta ble 5. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for
(
d eg) for tr a n s-Cl(Et
3
P )
2 3 2
P t[C(Cl)dP N(SiMe ) ] (Ib)
1
1
2
Cl(Et
3
P )
2
5 3 2
P t[µ-η ,η ,η -CtP {W(CO) }]P t(P Et ) (IV)
Distances
Pt-C(1) 1.990(7) Pt-Cl(2) 2.373(2) P(1)-N(1) 1.741(6)
Distances
Pt-P(2) 2.314(2) C(1)-P(1) 1.690(7) N(1)-Si(1) 1.744(6)
Pt-P(3) 2.313(2) Cl(1)-C(1) 1.778(7) N(1)-Si(2) 1.762(6)
Pt(1)-C(1) 1.952(9) Pt(2)-P(1) 2.292(3) W(1)-C(2) 2.042(13)
Pt(1)-P(3) 2.324(3) Pt(2)-P(4) 2.270(3) W(1)-C(3) 2.048(14)
Pt(1)-P(2) 1.977(5) Pt(2)-P(5) 2.285(3) W(1)-C(4) 2.014(12)
Pt(1)-Cl(1) 2.393(3) C(1)-P(1) 1.663(9) W(1)-C(5) 2.032(13)
Pt(2)-C(1) 2.104(9) P(1)-W(1) 2.531(3) W(1)-C(6) 1.978(11)
Bond Angles
Cl(2)-Pt-P(2)
Cl(2)-Pt-C(1)
P(2)-Pt-C(1)
C(1)-P(1)-C(2)
Pt-C(1)-P(1)
C(1)-P(1)-N(1)
144.4(4)
48.8(2)
158.1(2)
101.5(2)
147.54(10)
110.7(3)
Cl(2)-Pt-P(3)
P(2)-Pt-P(3)
P(3)-Pt-C(1)
Pt-C(1)-Cl(1)
Cl(1)-C(1)-P(1)
162.4(2)
104.2(2)
152.57(9)
93.41(8)
113.85(9)
Bond Angles
C(1)-Pt(1)-Cl(1)
C(1)-Pt(1)-P(3)
Cl(1)-Pt(1)-P(3)
C(1)-Pt(2)-P(1)
C(1)-Pt(2)-P(5)
P(1)-Pt(2)-P(5)
Pt(1)-C(1)-P(1)
Pt(2)-P(1)-C(1)
C(1)-Pt(1)-P(2)
179.1(3)
90.8(3)
89.37(10)
44.2(3)
149.0(3)
105.43(10)
145.2(6)
61.9(3)
Cl(1)-Pt(1)-P(2)
P(2)-Pt(1)-P(3)
C(1)-Pt(2)-P(4)
P(1)-Pt(2)-P(4)
P(4)-Pt(2)-P(5)
Pt(1)-C(1)-Pt(2)
Pt(2)-C(1)-P(1)
W(1)-P(1)-C(1)
W(1)-P(1)-Pt(2)
90.12(10)
169.82(11)
105.6(3)
149.29(11)
105.17(11)
140.8(5)
73.9(4)
136.1(3)
157.31(13)
a
Numbers in parentheses are estimated standard deviations
in the least significant digits.
lated which provided all non-hydrogen atoms from the E-map.
All non-hydrogen atoms were refined with anisotropic dis-
placement parameters. All hydrogen atoms were refined as
riding atoms with C-H distances of 0.96 Å. The hydrogen
atoms in methylene groups were refined with individual
isotropic displacement parameters, while methyl hydrogen
atoms were refined as groups. Selected bond distances and
bond angles are given in Table 4.
89.8(3)
a
Numbers in parentheses are estimated standard deviations
in the least significant digits.
atoms. One triethylphosphine group (P4) was disordered in
a 0.50:0.50 ratio and required the use of 426 restraints. The
P4 group is duplicated (P4′) in order to make a separate group,
both of which have the same parameters. These groups were
refined isotropically with additional restraints, and the other
triethylphosphine groups in the molecule were used to group
1
1
2
X-r a y Cr ysta llogr a p h ic Stu d y of Cl(Et
CtP {W(CO) }]P t(P Et (IV). Diffraction-quality crystals
were obtained by slow evaporation of an Et O solution of IV.
Data collection and reduction information are given in Table
. An orange crystal of IV was mounted on a glass fiber for
3 2
P ) P t[µ-η ,η ,η -
5
3 2
)
2
the two partially occupied groups in SHELTXTL SAME
33
restraints.
Selected bond distances and bond angles are
3
given in Table 5.
data collection. An initial set of cell constants was calculated
from reflections taken from three sets of 20 frames. Final cell
constants were calculated from a set of 5625 strong reflections
Ack n ow led gm en t. We thank the donors of the
Petroleum Research Fund (Grant 27360-AC3), admin-
istered by the American Chemical Society, and the
National Science Foundation (Grant CHE-9414242) for
support of this research.
taken during the data collection. The space group P2
1
/n was
unambiguously determined by systematic absences and in-
3
3
tensity statistics.
A hemisphere-type data collection was
employed in which a randomly oriented region of space was
surveyed to the extent of 1.3 hemispheres to a resolution of
Su p p or t in g In for m a t ion Ava ila b le: Tables of non-
hydrogen atomic coordinates and equiv isotropic parameters,
anisotropic displacement parameters, complete bond distances
and angles, hydrogen coordinates and isotropic diplacement
parameters, torsion angles, and unit cell and packing diagrams
for Ib and IV (20 pages). This material is contained in many
libraries on microfiche, immediately follows this article in the
microfilm version of the journal, can be ordered from the ACS,
and can be downloaded from the Internet; see any current
masthead page for ordering information and Internet access
instructions.
0
0
.84 Å. Three major swaths of frames were collected with
.30° steps in ω, providing a high degree of redundancy. A
successful direct methods solution was calculated which
provided most non-hydrogen atoms from the E-map. Several
full-matrix least-squares difference Fourier cycles were per-
formed which located the remainder of the non-hydrogen
atoms. All non-hydrogen atoms were refined with anisotropic
displacement parameters. Hydrogen atom positions were
generated with ideal geometries and refined as riding, isotropic
(33) SHELXTL-Plus V5.0; Siemens Industrial Automation Inc.,
Madison, WI, 1994.
OM980746U