Formation of a stable cationic hydridodimethylplatinum(IV) complex by the reaction of bis(μ-dimethyl sulfido)tetramethyldiplatinum(II) with protonated 1,4,7-triisopropyl-1,4,7-triazacyclononane. A first example of oxidative N-H addition to a platinum(II) complex

Article abstract of DOI:10.1023/A:1026376012458

The complex bis(μ-dimethyl sulfido)tetramethyldiplatinum(II) reacts with 1,4,7-triisopropyl-1,4,7-triazacyclopropanone (L) over the course of 24 h at room temperature in THF-d₈ to give [PtMe₂(L)] and PtMe₂(SMe₂)₂. Subsequent addition of 1 mol of trifluoromethanesulfonic acid results in immediate formation of a previously unknown stable cationic complex [PtMe₂H(L)]⁺SO ₃CF₃^-. This product can also be prepared by oxidative addition of the N-H bond of LH⁺SO₃CF ₃^- to the starting complex, which points to a higher basicity of the platinum atom in [PtMe₂(L)] compared with the nitrogen atom in the ligand L. The pK_a of the cationic hydride of platinum(IV) was estimated.

Full text of DOI:10.1023/A:1026376012458

Russian Journal of General Chemistry, Vol. 73, No. 6, 2003, pp. 842 846. Translated from Zhurnal Obshchei Khimii, Vol. 73, No. 6, 2003,
pp. 890 894.
Original Russian Text Copyright
2003 by Sobanov, Vedernikov, Dyuker, Solomonov.
Formation of a Stable Cationic Hydridodimethylplatinum(IV)
Complex by the Reaction
of Bis( -dimethyl sulfido)tetramethyldiplatinum(II)
with Protonated 1,4,7-Triisopropyl-1,4,7-triazacyclononane.
A First Example of Oxidative N H Addition
to a Platinum(II) Complex
A. A. Sobanov, A. N. Vedernikov, G. Dyuker, and B. N. Solomonov
Kazan State University, Kazan, Tatarstan, Russia
University of Duisburg, Germany
Received May 15, 2001
Abstract The complex bis( -dimethyl sulfido)tetramethyldiplatinum(II) reacts with 1,4,7-triisopropyl-
1
,4,7-triazacyclopropanone (L) over the course of 24 h at room temperature in THF-d to give [PtMe (L)] and
8 2
PtMe (SMe ) . Subsequent addition of 1 mol of trifluoromethanesulfonic acid results in immediate formation
2
2 2
+
of a previously unknown stable cationic complex [PtMe H(L)] SO CF . This product can also be prepared
by oxidative addition of the N H bond of LH SO CF to the starting complex, which points to a higher
2
3
3
+
3
3
basicity of the platinum atom in [PtMe (L)] compared with the nitrogen atom in the ligand L. The pK of the
2
a
cationic hydride of platinum(IV) was estimated.
Alkylhydridoplatinum(IV) complexes discovered
and characterized about five years ago [1 4] present
interest as model compounds or potential intermedia-
tes in stoichiometric and catalytic activation of hydro-
carbons with platinum(II) compounds [5]; they are
formed by the oxidative addition scheme. The dis-
covery that alkylplatinum(II) complexes are proto-
nated under the action of Brønsted acids has been an
important event in the history of alkylhydridopla-
tinum(IV) complexes. Such complexes are extremely
unstable even at low temperatures if they contain
monodentate N-, P-, or O-donor ligands [3], but their
stability is much enhanced by cis-chelating bidentate
carbon C H bonds in hydrocarbon media, we syn-
thesized a new stable highly lypophilic cationic
hydridomethyl platinum(IV) complex [PtMe H(tacn-i-
2
+
Pr )] SO CF (tacn-i-Pr is 1,4,7-triisopropyl-1,4,7-
3
3
3
3
triazacyclononane, L) (compound I). For the source
of the dimethylplatinum fragment we chose the
complex [PtMe (SMe )] (compound II) [8]. A dis-
2
2 2
tinguishing feature of the developed synthetic proce-
dure is that for the proton-donor reagent we used a
+
salt derived from the ligand L, LH SO CF , which is
3
3
much more convenient in operation [scheme (1)].
+
[PtMe (L )]2 + LH SO CF
2
3
3
[
2] and, especially, fac-chelating tridentate N-donor
+
[
PtMe H(L)] SO CF PtMe (L ) .
(1)
2
3
3
2
2
ligands [1]. We previously theoretically interpreted
the ability of the latter ligands to thermodynamic and
kinetic stabilization of d -alkylhydridopalladiums [6].
Some our predictions as to the existence of yet un-
known compounds of this class proved to be true [7].
The coordination of a fac-chelating ligand with a d8
metal brings the frontier orbitals closer to each other,
thus enhancing the nucleophilicity and basicity of the
complex.
Here L is the dimethyl sulfide ligand exchanged for
the ligand L in the course of the reaction.
6
Since in the course of the reaction platinum co-
ordinates both with nitrogen and with hydrogen, this
reaction can be considered as a first example of oxi-
dative addition of ammonium N H bond to pla
tinum(II).
To obtain further experimental evidence for our
theoretical predictions and aiming at designing lypo-
philic metal complexes capable of activating hydro-
We found that the exchange of the dimethyl sulfide
ligand in compound II for L is a slow reaction whose
equilibrium is characterized by ca. 50% conversion of
1
070-3632/03/7306-0842$25.00 2003 MAIK Nauka/Interperiodica

FORMATION OF A STABLE CATIONIC HYDRIDODIMETHYLPLATINUM(IV)
843
1
H NMR spectra (THF-d ) of the compounds present in the reaction mixtures
8
Compound
, ppm (J, Hz)
+
21.6 s (1H, PtH, 1JPtH 1390), 0.80 s (6H, PtCH , J
2
3
[
PtMe H(tacn-i-Pr )] CF SO
67), 1.26 d (6H, CCH , J
2
3
3
3
3
PtH
3
HH
3
3
6
.4), 1.29 d (6H, CCH , J
6.4), 1.43 d (6H, CCH3, JHH 6.6), 3.10 3.55 m
3
HH
(
CH and CH2)
[
PtMe (SMe )]
2 2
0.51 s (12H, PtCH3, 2JPtH 88), 2.74 s (12H, SCH3, 3JPtH 21)
2
2
84), 2.36 s (12H, SCH3, 3J
PtMe (SMe )
0.51 s (6H, PtCH , J
24)
2
2 2
3
PtH
PtH
3
tacn-i-Pr3
1.00 d (18H, CCH , J
6.2), 2.64 s (12H, NCH CH ), 2.86 heptet (3H, NCH,
3
HH 2 2
3
JHH 6.2)
+
3
a
b
[
tacn-i-Pr H] CF SO
1.22 d (18H, CCH , J
3
6.7), 2.80 2.95 m (6H, NCH ), 2.96 3.10 m (6H, NCH ),
HH
3
3
3
3
3
.28 heptet (3H, NCH, JHH 6.7), 9.9 s (1H, NH)
SMe2
CH4
2.09 s
0.23 s
+
compound II and is established within 20 30 h
scheme (2)].
[PtMe H(tacn-i-Pr )] CF SO , obtained by us, and
2 3 3 3
+
[
the spectra of solutions of [PtHMe (tacn)] CF SO in
2 3 3
acetone-d , reported in [7], , ppm: 19.5 s (1H, PtH,
6
1
2
[
PtMe (L )] + L
[PtMe (L)] + PtMe (L ) . (2)
JPtH 1339 Hz), 0.63 s (6H, PtCH , J 70 Hz), 3.17
2
2
2
2
2
3 PtH
m (6H, CH ), 3.35 m (6H, CH ), 5.28 br (1H, NH),
5.75 br (2H, NH).
2
2
Therefore, we first tried to synthesize compound I
in two stages: to exchange L for L in the absence of
protonating agent and to introduce a powerful protonat-
ing agent, trifuoromethanesulfonic acid, only after the
exchange equilibrium has been established.
The nonequivalence of the isopropyl groups fol-
lows from their nonequivalent positions: One of them
is attached to the nitrogen atom located trans to the
hydride ligand in, apparently, scewed conformation,
and, as follows from the quantum-chemical models of
these systems, rendering nonequivalent the other two
isopropyl groups. The isopropyl group that gives the
most downfield signal is likely to be located op-
positely to the hydride ligand.
On treatment with a small excess of trifluro-
methanesulfonic acid the complex dimethyl(1,4,7-tri-
isopropyl-1,4,7-triazacyclononane)platinum(II) formed
directly in the reaction mixture by scheme (2) im-
mediately and completely converts into compound I
[scheme (3)].
1
According to H NMR data, 40 min after addition
+
[
PtMe (L)] + HSO CF
[PtMe H(L)] SO CF . (3)
of trifluoromethanesulfonic acid, the reaction mixture
prepared from 1 mol of compound I, 1 mol of the
ligand L, and 1 mol of the acid contained three pla-
tinum complexes, [PtMe (SMe )] , PtMe (SMe )
2
3
3
2
3
3
+
The structure of the cation [PtMe H(tacn-i-Pr )]
2
3
1
was proved by H NMR. The spectrum in tetrahydro-
2
2
2
2
2 2
+
furan-d contains signals, , ppm, of the hydrogen
(III), and [PtMe H(tacn-i-Pr )] CF SO (I) in a
8
2 3 3 3
1
atom on platinum, 21.6 s (1H, PtH, J 1390 Hz),
two methyl groups, 0.51 s (6H, PtSH , J 67 Hz),
12:46:42 molar ratio. One day after, the starting bi-
nuclear complex I was consumed completely, and the
molar ratio between the two remaining complexes
III:I became equal to 45:55. Moreover, excess free
ligand L and its salt with excess trifluoromethane-
sulfonic acid, a little free dimethyl sulfide, and traces
of methane were present. The chemical shifts and
coupling constants of the mentioned compounds are
listed in the table.
PtH
2
3
PtH
CH protons of three nonequivalent isopropyl groups,
3
3
1
.26 d (6H, CCH , J 6.4 Hz), 1.29 d (6H, CCH ,
JHH 6.4 Hz), 1.43 d (6H, CCH , J
3
HH
3
3
3
6.6 Hz),
3
HH
ethylene fragments (ill-resolved multiplets), and iso-
propyl methine protons, 3.10 3.55 m (CH and CH2).
The multiplets at
3.10 3.20 and 3.21 3.32 ppm
form a pattern characteristic of the triazacyclononane
ring bound with a metal atom, and the multiplets at
In a sealed ampule in tetrahydrofuran purified over
potassium anthracene mirror, complex I is stable for
at least 1 month. On contact with air it slowly de-
composes with liberation of metallic platinum,
methane, and 1,4,7-triisopropyl-1,4,7-triazacyclo-
nonane complexes. Ethane was not found among the
3
.32 3.42 and 3.42 3.55 ppm (J 6.4 6.6 Hz) are
assigned to methine protons.
Further evidence for the proposed signal assign-
ment and structure of the hydride comes from the
1
similarity of the H NMR spectra of solutions of
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 73 No. 6 2003

844
SOBANOV et al.
decomposition products. After 10-h heating at 80 C,
the H NMR spectrum no longer shows signals in the
no hydride formation is observed. A possible reason
here is that the ligand exchange involving the posi-
tively charged ion of the monoprotonated amine
occurs very slowly.
1
PtMe resonance region.
2
1
In the H NMR spectrum measured short after
addition of the acid we found two closely located
The above result provides unambiguous evidence
showing that the platinum(II) atom in the triazacyclo-
nonane complex possesses a higher basicity than the
nitrogen atom in the free ligand. This result is also
consistent with data of Prokopchuk et al. [7] who
1
resonance signals, , ppm: 21.6 s (PtH, JPtH
1
1
390 Hz) and 21.8 s (PtH, JPtH 1434 Hz), with close
coupling constants. We suggest that they belong to
two conformers of compound I. Actually, rotation of
the isopropyl radical about the C N bonds gives rise
to three different staggered conformers of each of the
isopropyl groups: +gauche, gauche, and trans.
observed reversible protonation of PtMe (tacn) with
2
methanol when the latter was used as a solvent. Reac-
tion (1) can be considered as a first example of oxi-
dative addition of the N H bond of a tertiary
ammonium ion to platinum(II).
Moreover, rotation of the CH group of the ligand
2
about the C C bond changes the configuration of the
spirochiral fragment Pt(tacn), which increases the
number of possible rotational diastereomers. If the
barrier to transfer of at least one of them into the most
stable conformer is sufficiently high (> 92 kJ/mol),
then the appearance of two upfield signals with close
characteristics can be explained in terms of rotational
isomerism. The integral intensity ratio of primarily
observed signals is 83:17. After one day, only one
upfield signal remains ( 21.6 ppm), which, in the
context of the concept of retarded conformational
transitions, may suggest isomerization into the most
thermodynamically stable conformer.
To gain further information about the basicity of
the central metal atom in compound I, we, like the
above referees [7], could effect protonation of the
corresponding dimethylplatinum(II) complex with
such a weak acid as methyl alcohol. To this end, the
ligand-exchange reaction (2) was perfomed directly in
methanol-d , which allowed us to follow the reaction
4
1
progress by H NMR. It was found that the dimethyl-
platinum complex with the ligand L is not detected,
like in the case of the tetrahydrofuran solution, but
+
converts into the cationic species [PtMe D(tacn-i-Pr )]
2
3
whose counterion is the trideuteromethylate anion
present in the solution [scheme (4)].
Assuming that coordination of L with pla-
tinum(II) increases the basicity of the latter so that it
becomes more basic than the ligand nitrogen atom,
we attempted to make use of this property of the
platinum(II) derivatives studied for preparing complex
I by a simplified scheme not involving consecutive
ligand exchange [scheme (2)] and protonation
+
[PtMe (L )] + L + CD OD
[PtMe D(L)] CD O
2
2
3
2
3
+
PtMe (L ) .
(4)
2
2
Evidence for this conclusion comes the observation
1
in the H NMR spectrum ( , ppm) of signals as-
[
scheme (3)]. For the source of both ligand L and
protonating agent we took a 1:1 ammonium salt of
,4,7-triisopropyl-1,4,7-triazacyclononane with tri-
signable to the methyl groups on platinum in the
2
cationic hydride [0.74 s (PtCH , J 69 Hz)] and the
3
PtH
1
isopropyl methyl groups in the cation [PtMe D(tacn-i-
2
fluoromethanesulfonic acid.
+
3
Pr )] [1.25 d (CCH , J 6.5 Hz), 1.43 d (CCH3,
JHH 6.6 Hz)], analogous to those we found for
3
3
HH
3
The reaction of complex II with a mixture contain-
ing equimolar (per platinum) quantity of 1,4,7-triiso-
propyl-1,4,7-triazacyclononane and half the quantity
of trifluoromethanesulfonic acid, gave rise within 25
complex I in tetrahydrofuran-d , as well as those
8
+
observed for [PtMe D(tacn)] CD O in acetone-d [7]:
2
3
6
2
0.60 ppm, s (PtCH , J 69 Hz). The solution of
[PtMe D(L)] CD O in deuteromethanol is unstable
3
PtH
+
30 h at room temperature, to complete consumption
2 3
of the ammonium salt and formation of the target
compound I. The resulting H NMR spectrum con-
tained only one upfield signal ( 21.6 ppm) belong-
ing to the hydride ligand.
and decomposes completely within 1 h.
1
The experiments performed earlier and described
in the present work allow estimation of the basicity
of platinum in the complexes [PtMe (tacn)] and
2
+
Within 5 days at room temperature, the concentra-
tion of the amine salt remained almost unchanged, and
the starting platinum complex II disappeared almost
completely, forming only little PtMe (SMe ) and
[PtMe (tacn-i-Pr )]. According to [7], [PtHMe (tacn)]
2
3
2
CF SO does not change on treatment with excess
3
3
pyridine, and, consequently, its pK
a(PtH+)
is at least
higher than 5.3 (pKB of pyridine [9]). From our
present data on the proton transfer from LH onto the
2
2 2
+
methane. It is important to note that on mixing of
PtMe (SMe )] with the salt (1 mol protonated ligand
[
platinum atom in [PtMe (L)] follows the estimate
2
2
2
2
+
per 1 mol platinum) in the absence of free tacn-i-Pr3
pK (I) > pK (LH ) + 4, provided that the detection
a
a
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 73 No. 6 2003

FORMATION OF A STABLE CATIONIC HYDRIDODIMETHYLPLATINUM(IV)
845
limit of the nonprotonated
dimethylplatinum(II)
ampule. Tetrahydrofuran-d of analytical grade was
8
+
complex and the LH salt is less than 1% of the total
quantity of the reaction products. Furthermore, from
the deuteromethanol protonation experiment on the
assumption [I] = [MeO ] = [Pt] (total concentration
of platinum 0.01 M), [I]/([Pt] [I]) > 100 (corres-
ponds to the detection limit of the starting complex)
purified over a potassium anthracene mirror im-
mediately before use and distilled in a vacuum, collect-
ing the distillate directly into the cell (the residual
pressure over the solvent frozen with liquid nitrogen
was 10 3 10 mm). The cell was sealed off from the
vacuum line, and the reaction was performed. After
the reaction had been complete, the NMR ampule was
sealed off from the cell, and NMR spectra were re-
corded at regular intervals.
2
for [MeOH] 24.6 M, and, taking pK (MeOH) 15.5 [9],
a
the basicity of platinum in PtMe (tacn) corresponds
2
+
to pK [PtMe H(tacn) ] > 15.0.
a
2
Thus, we obtained a new stable cationic hydrido-
dimethylplatinum(V) complex and showed that the
basicity of the metal atom in the complex of dimethyl-
platinum(II) with 1,4,7-triisopropyl-1,4,7-triazacyclo-
nonane in tetrahydrofuran is higher than that of the
nitrogen atom in the free ligand. This finding allowed
us to develop a new method of synthesis of the target
compound via oxidative addition of the N H bond in
the corresponding ammonium salt to platinum(II).
Protonation of a mixture of [PtMe (SMe )] (II)
2
2 2
and tacn-i-Pr with trifluoromethanesulfonic acid.
3
Compound I, 13.4 mg, and 13.0 mg of tacn-i-Pr were
3
placed into the different knees of the cell, and 1 ml of
tetrahydrofuran-d into the knees. The resulting trans-
8
parent colorless solutions were mixed, and the reac-
tion mixture was left to stand for 24 h at 20 C. Tri-
fluoromethanesulfonic acid (2 l) was introduced by
breaking its containing evacuated glass ampule. By
NMR we found in the solution [PtMe (SMe )] ,
2
2 2
+
EXPERIMENTAL
PtMe (SMe ) , and [PtMe H(tacn-i-Pr )] CF SO in a
2 2 2 2 3 3 3
1
2:46:42 molar ratio. A day after, the starting bi-
1
The H NMR spectra were measured on Varian
nuclear complex I was consumed completely, and the
III:I ratio became 45:55. The solution contained
excess free ligand L, its salt with excess trifluoro-
methanesulfonic acid, and traces of dimethyl sulfide
and methane. The NMR parameters of these com-
pounds are listed in the table.
Unity-300 (300 MHz) and Bruker DRX-500
500.1 MHz) instruments.
(
Bis( -dimethyl sulfido)tetramethyldiplatinum(II)
II) was synthesized by the procedure in [10].
(
1
3
,4,7-Triisopropyl-1,4,7-triazacyclononane(tacn-
Reaction of complex II with a mixture of [tacn-i-
i-Pr ) was prepared by a modified procedure [11]
+
Pr H ]SO CF and tacn-i-Pr . Complex I, 13.2 mg,
and a mixture of tacn-i-Pr with [tacn-i-Pr H] CF SO
were placed into different knees of the cell. The mix-
ture was prepared by adding 2 l of trifluorome-
thanesulfonic acid to a solution of 13.0 mg of tacn-i-
Pr in 1.5 ml of dry acetone, followed by vacuum
evaporation to dryness. The solid compounds were
dissolved in 1 ml of tetrahydrofuran-d , and the solu-
tions were mixed. According to H NMR data, after
without isolation of the ligand as a salt. A solution of
3
3
3
3
+
1
.51 g of 1,4,7-triazacyclononane and 4.84 g iso-
propyl bromide in 7.5 ml of toluene was stirred at
0 C for 4 h. A colorless precipitate formed. Potas-
sium hydroxide, 2.5 g, was stirred to the mixture, and
it was allowed to stir for an additional 4 h at 80 C.
The precipitate of potassium bromide of filtered off
and washed with several portions of toluene. The
combined toluene solutions were evaporated, dried at
reduced pressure, and distilled at 100 C (0.05 mm) to
obtain 2.12 g (71%) of the reaction product as a color-
less oil. H NMR spectrum (CDCl , 300 MHz), ,
ppm: 0.96 d (18H, CCH , J 6.5 Hz), 2.62 s (12H,
NCH CH ), 2.87 heptet (3H, NCH, J 6.5 Hz). H
3
3
3
3
8
3
8
1
2
5 30 h at room temperature the ammonium salt
disappeared completely, and compound I formed. After
days at room temperature, the concentration of the
1
5
3
3
amine salt did not change, while the starting platinum
complex II disappeared almost completely, forming a
little PtMe (SMe ) and methane (see table).
3
HH
3
1
2
2
HH
NMR spectrum (C D , 500 MHz), , ppm: 0.97 d
18H, CCH , J 6.6 Hz), 2.63 s (12H, NCH CH ),
.79 heptet (3H, NCH, J 6.6 Hz). H NMR spec-
HH
2
2 2
6
6
3
(
2
3 HH 2 2
3
1
Formation of platinum(IV) hydrides in me-
thanolic [PtMe (SMe )] and tacn-i-Pr . Methanol-
d4 (0.8 ml) degassed and dried over molecular sieves
was added under argon to a mixture of 6.2 mg of com-
pound II and 6.5 mg of tacn-i-Pr , placed in an NMR
ampule. The ampule was exposed to ultrasound for a
short time for faster dissolution of compound II. After
that, the H NMR spectrum of the reaction mixture
2
2
2
3
trum [(CD ) CO, 300 MHz)], , ppm: 0.95 d (18H,
3
2
3
CCH3, JHH 6.6 Hz), 2.60 s (12H, NCH CH ),
2
2
3
2
.80 heptet (3H, NCH, J
6.6 Hz).
HH
3
+
Complex [PtMe H(tacn-i-Pr )] SO CF (I). All
2
3
3
3
experiments were performed in a glass all-sealed
evacuated cell comprising two conjoint vertical cylin-
drical sections (knees) and equipped with an NMR
1
was recorded. The spectrum contained signals of the
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 73 No. 6 2003

846
SOBANOV et al.
Pt Me groups of the cationic hydride [ , 0.74 ppm, s
4. Hill, G.S., Rendina, L.M., and Puddephatt, R.J.,
Organometallics, 1995, vol. 14, no. 10, p. 4966;
Hill, G.S. and Puddephatt, R.J., J. Am. Chem. Soc.,
1996, vol. 118, no. 36, p. 8745.
2
(
Pt CH , J
69 Hz)] and of the isopropyl methyl
3
PtH
+
groups of the cation [PtMe D(tacn-i-Pr )]
1
[
2
3
3
.25 ppm, d (C CH , J
6.5 Hz), 1.43 ppm, d
3
HH
3
(
C CH , J 6.6 Hz)]. The solution of the complex
3
HH
5. Gol’dshleger, N.F., Tyabin, N.B., Shilov, A.E., and
Shteinman, A.A., Zh. Fiz. Khim., 1969, vol. 43, no. 8,
p. 2174.
+
[PtMe D (L)] CD O completely decomposes within
2
3
1
h.
6
. Vedernikov, A.N., Shamov, G.A., and Solomo-
nov, B.N., Zh. Obshch. Khim., 1999, vol. 69, no. 7,
p. 1144; Vedernikov, A.N., Shamov, G.A., and Solo-
monov, B.N., Ross. Khim. Zh., 1999, vol. 43, no. 1,
p. 22.
ACKNOWLEDGMENTS
The authors are grateful for financial support the
Russian Foundation for Basic Research (project no.
1-03-32692a) and DAAD Service for Academic
0
7
8
. Prokopchuk, E.M., Jenkins, H.A., and Puddephatt, R.J.,
Organometallics, 1999, vol. 18, no. 15, p. 2861.
Exchange (Germany) (stipend A/99/41055).
. Byers, P.K., Canty, A.J., and Honeyman, R.T., Adv.
Organomet. Chem., 1992, vol. 34, no. 1, p. 1;
Scott, J.D. and Puddephatt, R.J., Organometallics,
REFERENCES
1
2
. Canty, A.J., Dedieu, A., Jin, H., Milet, A., and Rich-
mond, M.K., Organometallics, 1996, vol. 15, no. 12,
p. 2845; O’Reilly, S.A., White, P.S., and Temple-
ton, J.L., J. Am. Chem. Soc., 1996, vol. 118, no. 24,
p. 5684.
1
986, vol. 5, no. 8, p. 1538; Scott, J.D. and Puddep-
hatt, R.J., Organometallics, 1986, vol. 5, no. 12,
p. 2522; Bancroft, D.P., Cotton, F.A., Falvello, L.R.,
and Schwotzer, W., Inorg. Chem., 1986, vol. 25, no. 6,
p. 763.
. De Felice, V., De Renzi, A., Panunzi, A., and Tesau-
ro, D., J. Organomet. Chem., 1995, vol. 488, nos. 1 2,
C13; Stahl, S.S., Labinger, J.A., and Bercaw, J.E.,
J. Am. Chem. Soc., 1995, vol. 117, no. 36, p. 9371;
Luinstra, G.A., Wang, L., Stahl, S.S., Labinger, J.A.,
and Bercaw, J.E., J. Organomet. Chem., 1995,
vol. 504, nos. 1 2, p. 75.
9
. Rabinovich, V.A. and Khavin, V.Ya., Kratkii khimi-
cheskii spravochnik (Concise Chemical Handbook),
Leningrad: Khimiya, 1991.
10. Scott, J.D. and Puddephatt, R.J., Organometallics,
1983, vol. 2, no. 11, p. 1643.
1
1. Haselhorst, G., Stoetzel, S., Strassburger, A., Walz, W.,
Wieghardt, K., and Nuber, B., J. Chem. Soc., Dalton
Trans., 1993, no. 1, p. 83.
3
. Stahl, S.S., Labinger, J.A., and Bercaw, J.E., J. Am.
Chem. Soc., 1996, vol. 118, nos. 25, p. 5961.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 73 No. 6 2003