Methyl(hydrido)platinum(IV) complexes: X-ray structure of the first (μ-hydrido)diplatinum(IV) complex

Article abstract of DOI:10.1021/om960975l

The complex fac-[PtMe₃(SO₃CF3)(bu₂bpy)] (1) (bu₂bpy = 4,4′-di-tert-butyl-2,2′-bipyridine) reacts with NaBH₄ to give [Pt₂(μ-H)Me₆(bu₂bpy)₂]SO ₃CF₃ (2), which is the first example of a (μ-hydrido)diplatinum(IV) complex. Complex 2 was fully characterized on the basis of microanalytical, ¹H and ¹⁹⁵Pt NMR spectroscopic, and X-ray crystallographic data. The reaction of 1 with a large excess of NaBH₄ results in the formation of an equilibrium mixture of 2 and fac-[PtHMe₃(bu₂bpy)] (3). Complex 3 was characterized by ¹H NMR spectroscopy in solution but could not be isolated in pure form due to the ease of reversion to 2. Both complexes 2 and 3, which have no ligand than can easily dissociate, are thermally stable to reductive elimination of methane (both in solution and, in the case of complex 2, in the solid state) and to isotopic exchange within Pt(D)CH₃ groups, thus giving strong support to the theory that both reactions must occur from within a five-coordinate intermediate. Complex 2 reacts slowly with HX (HX = HCl, HO₂CCF₃, HSC₆H₅, NH₄⁺) to give either 2 equiv of fac-[PtClMe₃(bu₂bpy)] (4), fac- [PtMe₃(O₂CCF₃)(bu₂bpy)](5), and fac-[PtMe₃(NH₃)(bu₂bpy)]-SO₃CF ₃ (6) or 1 equiv of [Pt₂(μ-SC₆H₅)Me₆(bu ₂bpy)₂]SO₃CF₃ (7), respectively. Qualitatively, the relative rates of these reactions follow the order of acid strength, i.e. HCl ≈ HO₂CCF₃ ? HSC₆H₅, indicating that the rate-determining step involves electrophilic attack of H⁺ on 2. Complex 2 reacts very slowly with nucleophiles such as PPh₃ to give 1 equiv of fac-[PtMe₃(PPh₃)(bu₂bpy)]SO₃CF ₃ (8) and 1 equiv of 3. The reaction of CCl₄ with 2 gives fac-[PtClMe₃(bu₂bpy)] (4), [PtCl₂Me₂(bu₂bpy)] (11), and mer-[PtCl₃Me(bu₂bpy)] (12) in a 1.0:0.8: 0.2 product ratio but without formation of chloroform.

Full text of DOI:10.1021/om960975l

Organometallics 1997, 16, 1209-1217
1209
Meth yl(h yd r id o)p la tin u m (IV) Com p lexes: X-r a y
Str u ctu r e of th e F ir st (µ-Hyd r id o)d ip la tin u m (IV)
Com p lex
Geoffrey S. Hill, J agadese J . Vittal, and Richard J . Puddephatt*
Department of Chemistry, The University of Western Ontario,
London, Ontario, Canada N6A 5B7
Received November 18, 1996X
The complex fac-[PtMe3(SO3CF3)(bu2bpy)] (1) (bu2bpy ) 4,4′-di-tert-butyl-2,2′-bipyridine)
reacts with NaBH4 to give [Pt2(µ-H)Me6(bu2bpy)2]SO3CF3 (2), which is the first example of
a (µ-hydrido)diplatinum(IV) complex. Complex 2 was fully characterized on the basis of
1
microanalytical, H and 195Pt NMR spectroscopic, and X-ray crystallographic data. The
reaction of 1 with a large excess of NaBH4 results in the formation of an equilibrium mixture
1
of 2 and fac-[PtHMe3(bu2bpy)] (3). Complex 3 was characterized by H NMR spectroscopy
in solution but could not be isolated in pure form due to the ease of reversion to 2. Both
complexes 2 and 3, which have no ligand that can easily dissociate, are thermally stable to
reductive elimination of methane (both in solution and, in the case of complex 2, in the solid
state) and to isotopic exchange within Pt(D)CH3 groups, thus giving strong support to the
theory that both reactions must occur from within a five-coordinate intermediate. Complex
2 reacts slowly with HX (HX ) HCl, HO2CCF3, HSC6H5, NH4+) to give either 2 equiv of
fac-[PtClMe3(bu2bpy)] (4), fac- [PtMe3(O2CCF3)(bu2bpy)](5), and fac-[PtMe3(NH3)(bu2bpy)]-
SO3CF3 (6) or 1 equiv of [Pt2(µ-SC6H5)Me6(bu2bpy)2]SO3CF3 (7), respectively. Qualitatively,
the relative rates of these reactions follow the order of acid strength, i.e. HCl ≈ HO2CCF3
. HSC6H5, indicating that the rate-determining step involves electrophilic attack of H+ on
2. Complex 2 reacts very slowly with nucleophiles such as PPh3 to give 1 equiv of fac-
[PtMe3(PPh3)(bu2bpy)]SO3CF3 (8) and 1 equiv of 3. The reaction of CCl4 with 2 gives fac-
[PtClMe3(bu2bpy)] (4), [PtCl2Me2(bu2bpy)] (11), and mer-[PtCl3Me(bu2bpy)] (12) in a 1.0:0.8:
0.2 product ratio but without formation of chloroform.
Sch em e 1
In tr od u ction
Several research groups have recently reported the
first examples of a fundamentally important class of
organometallic compounds, alkyl(hydrido)platinum(IV)
complexes.1 These complexes are proposed intermedi-
ates in the protonolysis of the Pt-C bond and in alkane
activation by Pt(II). In most of these reports, complexes
of formula [PtH(X)R2(NN)] (X ) halide, O2CCF3, SO3-
CF3; R ) CH3, CH2Ph; NN ) a bidentate nitrogen-donor
ligand) are formed by the trans oxidative addition of HX
to the corresponding dialkylplatinum(II) complex, [PtR2-
(NN)],1 and are usually characterized only in situ by
low-temperature 1H NMR spectroscopy because, at room
temperature, they rapidly decompose.1a,d-e The pro-
posed mechanism of this decomposition involves initial
dissociation of the ligand trans to the hydride (X-), to
give the five-coordinate intermediate [PtHR2(NN)]+
which then easily reductively eliminates alkane (Scheme
1).
ported examples of methyl(hydrido)platinum(IV) com-
plexes that are truly stable to the reductive elimination
of CH4 of the type [PtHMe2(NN′N′′)] {NN′N′′ ) a tris-
(pyrazolyl)borate ligand].1b,c In these complexes, the
ligand trans to hydride is a strongly coordinating
pyrazolyl group of the NN′N′′ ligand. In this work, the
aim of isolating a stable methyl(hydrido)platinum(IV)
complex is the same, but the approach was different.
The objective was to synthesize the complex fac-
[PtHMe3(bu2bpy)] (bu2bpy ) 4,4′-di-tert-butyl-2,2′-bipy-
ridine). This complex should have no easily dissociated
group and so should be stable to reductive elimination,
but it should possess interesting reaction chemistry
since it contains mutually trans methyl and hydrido
ligands (both with large trans effects) leading to stronger
hydridic character than in the pyrazolylborate com-
plexes discussed above. By analogy, the mutually trans
This suggests that a complex where all ligands are
strongly bound, such as [PtH(X)Me2(NN)], where X
cannot easily dissociate from platinum, would be stable
to the reductive elimination of CH4. This principle was
recognized recently by two research groups who re-
X Abstract published in Advance ACS Abstracts, February 15, 1997.
(1) (a) Stahl, S. S.; Labinger, J . A.; Bercaw, J . E. J . Am. Chem. Soc.
1996, 118, 5961. (b) O’Reilly, S. A.; White, P. S.; Templeton, J . L. J .
Am. Chem. Soc. 1996, 118, 5684. (c) Canty, A. J .; Dedieu, A.; J in, H.;
Milet, A.; Richmond, M. K. Organometallics 1996, 15, 2845. (d) Hill,
G. S.; Rendina, L. M.; Puddephatt, R. J . Organometallics 1995, 14,
4966. (e) De Felice, V.; De Renzi, A.; Panunzi, A.; Tesauro, D. J .
Organomet. Chem. 1995, 488, C13.
S0276-7333(96)00975-2 CCC: $14.00 © 1997 American Chemical Society

1210 Organometallics, Vol. 16, No. 6, 1997
Ta ble 1. Selected 1H NMR Sp ectr oscop ic Da ta for Com p lexes 1-12e
Hill et al.
δ(1H)
complex
Pt-Mea
Pt-Meb
1.21 [s, 6H, 2J (PtH) ) 66.5 Hz]
tBu
other
1c
2d
3c
4c
5c
6d
7c
0.64 [s, 3H, 2J (PtH) ) 87.0 Hz]
1.49 (s, 18H)
0.13 [s, 6H, 2J (PtH) ) 65.9 Hz]
0.47 [s, 12H, 2J (PtH) ) 69.6 Hz] 1.49 (s, 36H)
-11.7 [s, 1H, 1J (PtH) ) 442 Hz, Pt-H]
-7.0 [s, 1H, 1J (PtH) ) 8.5 Hz, Pt-H]
- 0.79 [s, 3H, 2J (PtH) ) 43.0 Hz] 0.75 [s, 6H, 2J (PtH) ) 66.0 Hz]
1.48 (s, 18H)
1.46 (s, 18H)
1.46 (s, 18H)
1.47 (s, 18H)
0.36 [s, 3H, 2J (PtH) ) 74.5 Hz]
0.34 [s, 3H, 2J (PtH) ) 76.4 Hz]
0.31 [s, 3H, 2J (PtH) ) 71.5 Hz]
0.36 [s, 6H, 2J (PtH) ) 69.8 Hz]
1.99 [s, 6H, 2J (PtH) ) 69.7 Hz]
1.98 [s, 6H, 2J (PtH) ) 67.4 Hz]
1.04 [s, 6H, 2J (PtH) ) 67.8 Hz]
2.30 [br s, 3H, 2J (PtH) ) ca. 17.5 Hz, Pt-NH3]
6.55 [t, 1H, p-SC6H5], 6.11 [dd, 2H, m-SC6H5],
5.43 [d, 2H, o-SC6H5]
1.15 [s, 12H, 2J (PtH) ) 69.3 Hz] 1.37 (s, 36H)
8c
9c
0.65 [s, 6H, 2J (PtH) ) 44.0 Hz]
0.15 [s, 3H, 2J (PtH) ) 63.4 Hz]
0.84 [s, 6H, 2J (PtH) ) 72.0 Hz]
1.09 [s, 6H, 2J (PtH) ) 70.6 Hz]
1.49 (s, 18H)
1.43 (s, 18H)
6.56 [m, 1H, p-SC6H5], 6.35 [m, 2H, m-SC6H5],
6.32 [m, 2H, o-SC6H5]
10c
11c
12c
0.52 [s, 3H, 2J (PtH) ) 59.8 Hz]
1.33 [s, 6H, 2J (PtH) ) 67.5 Hz]
1.85 [s, 6H, 2J (PtH) ) 69.5 Hz]
2.69 [s, 3H, 2J (PtH) ) 68.0 Hz]
1.44 (s, 18H)
1.46 (s, 18H)
1.50 (s, 9H),
1.49 [s, 9H]
a
b
d
Pt-Me cis to bu2bpy. Pt-Me trans to bu2bpy. c In acetone-d6. In CD2Cl2. e Quoted multiplicities do not include 195Pt satellite signals.
Sch em e 2
methyl ligands in the tetramethylplatinum(IV) complex
[PtMe4(bpy)] (bpy ) 2,2′-bipyridine) have been shown
to readily react with a variety of electrophilic and
unsaturated reagents.2 It will be seen that the desired
complex fac-[PtHMe3(bu2bpy)] could be generated in
solution by reaction of fac- [PtMe3(SO3CF3)(bu2bpy)] (1)
with NaBH4, but the major product proved to be the
binuclear cationic complex, [Pt2(µ-H)Me6(bu2bpy)2]SO3-
CF3 (2), which is the first example of a (µ-hydrido)-
diplatinum(IV) complex and which is shown to have
interesting properties. A portion of this work has been
reported in an earlier communication.3
Resu lts a n d Discu ssion
Syn th esis a n d Ch a r a cter iza tion of [P t2(µ-H)Me6-
(bu 2bp y)2]SO3CF 3 (2). The reaction of [PtMe2(bu2bpy)]
nances in a 2:1 intensity ratio due to the methylplati-
with MeOSO2CF3 in diethyl ether solution quantita-
tively affords fac-[PtMe3(SO3CF3)(bu2bpy)] (1) as an off-
white solid. The 1H NMR spectrum (acetone-d6) of 1
shows the expected three sets of aromatic resonances
and one tert-butyl resonance of the two equivalent
pyridyl constituents of the bu2bpy ligand. The two
methylplatinum resonances appear in a 2:1 intensity
ratio at δ ) 1.21 [2J (PtH) ) 66.5 Hz] and δ ) 0.64
[2J (PtH) ) 87.0 Hz], respectively (Table 1). These
magnitudes of 2J (PtH) are typical for methylplati-
num(IV) ligands trans to bu2bpy and trans to SO3CF3
respectively.1d,4
2
num groups trans to bu2bpy [δ ) 0.47, J (PtH) ) 69.6
Hz] and trans to hydride [δ ) 0.13, 2J (PtH) ) 65.9 Hz],
respectively (Table 1). Both peaks showed a small
coupling with the hydrido ligand [3J (HH) ) 1.0 Hz in
1
each case]. The most convincing H NMR evidence for
a bridging hydrido ligand comes from the low-frequency
1
Pt-H resonance at δ ) -11.7 with J (PtH) ) 442 Hz.
The resonance appears as a 1:8:18:8:1 multiplet due to
coupling to 195Pt, thus proving the presence of a Pt2(µ-
H) group.5 This Pt-H resonance is absent in the 1H
NMR spectrum of [Pt2(µ-D)Me6(bu2bpy)2]SO3CF3 (2*),
prepared using NaBD4. The 2H{1H} NMR spectrum
(CH2Cl2) of complex 2* shows only the expected singlet
Treatment of fac-[PtMe3(SO3CF3)(bu2bpy)] (1) with
NaBH4 in THF solution affords the first binuclear
platinum(IV) hydride complex [Pt2(µ-H)Me6(bu2bpy)2]-
SO3CF3 (2), which was isolated as a yellow powder in
83% yield (Scheme 2).
1
1
at δ ) -11.7 with J (PtD) ) 68.4 Hz.6 The H-coupled
195Pt NMR spectrum (THF-d8) of 2 contains a doublet
at δ ) -1238 due to coupling with the bridging hydrido
ligand [1J (PtH) ) 440 Hz], thus proving the presence
of only a single µ-H ligand. The 195Pt NMR spectrum
(CD2Cl2) of [Pt2(µ-D)Me6(bu2bpy)2]SO3CF3 (2*) shows
only a broad singlet at δ ) -1240, since the line width
(∆ν1/2 ) ca. 160 Hz) is greater than the coupling 1J (PtD).
The 1H NMR spectrum of 2 is essentially unchanged
from room temperature to -90 °C.
1
The H NMR spectrum (CD2Cl2) of complex 2 shows
three aromatic resonances and one tert-butyl resonance
due to the two equivalent pyridyl groups of the bu2bpy
ligand. These data rule out the alternative isomer with
µ-H trans to nitrogen, which would have nonequivalent
pyridyl groups. There are two methylplatinum reso-
The proposed structure of [Pt2(µ-H)Me6(bu2bpy)2]SO3-
CF3 (2) was confirmed by X-ray crystallography. An
ORTEP diagram of 2 is shown in Figure 1, while Table
2 contains selected bond distances and angles. The
X-ray molecular structure of 2‚THF contains two very
(2) (a) Hux, J . E.; Puddephatt, R. J . Inorg. Chim. Acta 1985, 100, 1.
(b) Hux, J . E.; Puddephatt, R. J . J . Organomet. Chem. 1988, 346, C31.
(3) Hill, G. S.; Puddephatt, R. J . J . Am. Chem. Soc. 1996, 118, 8745.
(4) For example, see: (a) Rendina, L. M.; Vittal, J . J .; Puddephatt,
R. J . Organometallics 1995, 14, 1030. (b) Anderson, C. M.; Crespo, M.;
J ennings, M. C.; Lough, A. J .; Ferguson, G.; Puddephatt, R. J .
Organometallics 1991, 10, 2672. (c) Monaghan, P. K.; Puddephatt, R.
J . J . Chem. Soc., Dalton Trans. 1988, 595. (d) Crespo, M.; Puddephatt,
R. J . Organometallics 1987, 6, 2548. (e) J awad, J .; Puddephatt, R. J .
J . Chem. Soc., Dalton Trans. 1977, 1466. (f) Kuyper, J . Inorg. Chem.
1977, 16, 2171. (g) J awad, J .; Puddephatt, R. J . J . Organomet. Chem.
1976, 117, 297. (h) Appleton, T. G.; Clark, H. C.; Manzer, L. E. Coord.
Chem. Rev. 1973, 10, 335.
(5) (a) Brown, M. P.; Cooper, S. J .; Frew, A. A.; Manojlovic-Muir,
Lj.; Muir, K. W.; Puddephatt, R. J .; Thompson, M. A. J . Chem. Soc.,
Dalton Trans 1982, 299. (b) Brown, M. P.; Puddephatt, R. J .; Rashidi,
M.; Seddon, K. R. J . Chem. Soc., Dalton Trans. 1978, 516.
(6) γH/γD ) 6.51 ≈ 1J (PtH)/1J (PtD) ) 6.47.

Methyl(hydrido)platinum(IV) Complexes
Organometallics, Vol. 16, No. 6, 1997 1211
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles (d eg) in [P t2(µ-H)Me6(bu 2bp y)2]SO3CF 3‚THF
(A) Bond Distances
Pt(1)-H
1.69(2)
3.388(1)
2.01(2)
2.04(2)
2.09(2)
2.15(1)
2.12(1)
Pt(2)-H
1.70(2)
2.02(2)
2.05(1)
2.11(2)
2.15(1)
2.15(1)
Pt(1)-Pt(2)
Pt(1)-C(1)
Pt(1)-C(2)
Pt(1)-C(3)
Pt(1)-N(1)
Pt(1)-N(2)
Pt(2)-C(4)
Pt(2)-C(5)
Pt(2)-C(6)
Pt(2)-N(3)
Pt(2)-N(4)
(b) Bond Angles
Pt(1)-H-Pt(2)
173.5(71)
87.0(7)
88.9(7)
173.2(6)
98.9(5)
89.1(7)
98.4(6)
174.0(6)
87.1(7)
89.6(6)
177.8(6)
75.7(4)
C(4)-Pt(2)-C(5)
C(4)-Pt(2)-C(6)
C(4)-Pt(2)-N(3)
C(4)-Pt(2)-N(4)
C(5)-Pt(2)-C(6)
C(5)-Pt(2)-N(3)
C(5)-Pt(2)-N(4)
C(6)-Pt(2)-N(3)
C(6)-Pt(2)-N(4)
C(6)-Pt(2)-Pt(1)
N(3)-Pt(2)-N(4)
87.5(7)
88.6(8)
173.8(6)
97.7(6)
89.6(8)
98.1(6)
174.2(6)
89.0(6)
88.1(6)
176.8(6)
76.6(4)
C(1)-Pt(1)-C(2)
C(1)-Pt(1)-C(3)
C(1)-Pt(1)-N(1)
C(1)-Pt(1)-N(2)
C(2)-Pt(1)-C(3)
C(2)-Pt(1)-N(1)
C(2)-Pt(1)-N(2)
C(3)-Pt(1)-N(1)
C(3)-Pt(1)-N(2)
C(3)-Pt(1)-Pt(2)
N(2)-Pt(1)-N(1)
(c) Torsion Angles
C(1)-Pt(1)-Pt(2)-C(4)
C(1)-Pt(1)-Pt(2)-C(5)
C(2)-Pt(1)-Pt(2)-N(3)
C(2)-Pt(1)-Pt(2)-C(5)
N(2)-Pt(1)-Pt(2)-C(4)
N(1)-Pt(1)-Pt(2)-N(3)
-43.14(0.70)
44.50(0.68)
55.65(0.62)
-42.52(0.76)
55.77(0.61)
-42.75(0.43)
N(1)-Pt(1)-Pt(2)-N(4)
N(2)-Pt(1)-Pt(2)-N(4)
N(1)-C(5A)-C(5B)-N(2)
N(3)-C(5C)-C(5D)-N(4)
C(4A)-C(5A)-C(5B)-C(4B)
C(4C)-C(5C)-C(5D)-C(4D)
33.80(0.45)
-41.86(0.46)
-2.94(1.82)
3.87(1.83)
-6.84(2.26)
3.21(2.22)
Pt(1)-N(2) and N(3)-Pt(2)-N(4) bond angles of 75.7(4)
and 76.6(4)°, respectively, which depart significantly
from the ideal 90° octahedral angle, due to the restricted
bite of the bu2bpy ligand.7
The sets of atoms Pt(1), C(1), C(2), N(1), N(2) and
Pt(2), C(4), C(5), N(3), N(4) form well-defined planes
(rms ∆ ) 0.030 and 0.012, respectively) that are nearly
parallel to each other [angle between planes ) 3.6(5)°].
The bonds in these two planes adopt a staggered
conformation about the Pt(1)-Pt(2) vector such that the
C(1)-Pt(1)-Pt(2)-C(5) torsion angle is 44.5(0.7)°. Fur-
thermore, the two bu2bpy ligands adopt a syn arrange-
ment such that the centroid of the N(1)C(1A)C(2A)C(3A)-
C(4A)C(5A) ring lies above the midpoint of the C(5C)-
C(5D) bond. This arrangement minimizes the repul-
sions between the tert-butyl groups of adjacent bu2bpy
ligands while still maintaining a significant degree of
π-stacking between the pyridyl groups. The bu2bpy
ligands show no exceptional features, and each consists
of two planar rings (rms ∆ < 0.018 Å for all four rings)
that are twisted about the C-C single bonds such that
the torsion angles for C(4B)-C(5B)-C(5A)-C(4A) and
C(4C)-C(5C)-C(5D)-C(4D) are -6.84(2.26) and 3.21-
(2.22)°, respectively. The two bu2bpy ligands are sig-
nificantly tilted from the corresponding PtMe2N2 planes
and from one another (Figure 1). For example, the
N(1)C(1A)C(2A)C(3A)C(4A)C(5A) and N(2)C(1B)C(2B)-
C(3B)C(4B)C(5B) planes are tilted from the Pt(1)C(1)-
C(2)N(1)N(2) plane by 16.5(8) and 13.2(8)°, respectively,
and the N(3)C(1C)C(2C)C(3C)C(4C)C(5C) and N(4)-
C(1D)C(2D)C(3D)C(4D)C(5D) planes are tilted from the
Pt(2)C(4)C(5)N(3)N(4) plane by 12.2(8) and 8.7(6)°,
respectively. This is most certainly a result of interli-
gand repulsion of the tert-butyl groups of the bu2bpy
ligands. However, the observation of only single reso-
nances for the tert-butyl protons and the MePt protons
trans to nitrogen in 2 at -90 °C indicates that there is
only a small barrier to rotation about the PtHPt axis.
F igu r e 1. ORTEP diagram of [Pt2(µ-H)Me6(bu2bpy)2]+ (2).
Thermal ellipsoids show the 50% probability level. The
hydrogen atoms of the methylplatinum and bu2bpy ligands
have been omitted for clarity. The disorder of the methyl
groups at C(6c) is not shown.
similar fac-[PtMe3] units bridged by H. The lengths of
the Pt(1)-C(1), Pt(1)-C(2), Pt(2)-C(4), and Pt(2)-C(5)
bonds do not differ significantly [ranging from 2.01(2)
to 2.047(2) Å] and are of typical magnitude for a
methylplatinum(IV) ligand trans to bu2bpy.7 The Pt-C
bond lengths of the two methylplatinum ligands trans
to hydride are very similar [Pt(1)-C(2) ) 2.09(2) Å,
Pt(2)-C(6) ) 2.11(2) Å] and are longer than the meth-
ylplatinum ligands trans to bu2bpy. Therefore, the
µ-hydrido ligand has a larger trans influence than bu2-
1
bpy. This agrees with the data obtained from the H
NMR spectrum of 2 in which the magnitude of 2J (PtH)
for the Pt-Me ligands trans to bu2bpy is slightly larger
than for the Pt-Me ligands trans to hydride (Table 1).
The geometries at the platinum centers are close to
octahedral. The only notable exceptions are the N(1)-
(7) For example, see: (a) Levy, C. J .; Vittal, J . J .; Puddephatt, R. J .
Organometallics 1996, 15, 2108. (b) Rendina, L. M.; Vittal, J . J .;
Puddephatt, R. J . Organometallics 1996, 15, 2108.
The µ-hydrido ligand in 2 was successfully, though
not accurately, located. Typically, M(µ-H)M bonds are

1212 Organometallics, Vol. 16, No. 6, 1997
Hill et al.
bent and are best represented as 3c-2e- bonds with a
significant degree of concurrent M-M and M-H bond-
ing.8 The observation of near linearity of the Pt(1)-
H-Pt(2) angle [173(7)°] and of a large Pt(1)‚‚‚Pt(2)
separation [3.388(1) Å] indicates that there is very little,
if any, Pt-Pt bonding in 2.5a,9 The near linearity of the
Pt-H-Pt group is probably a direct result of steric
constraints due to the presence of the octahedral
platinum centers.
F or m a tion a n d Ch a r a cter iza tion of fa c-[P tHMe3-
(bu 2bp y)] (3). Reaction of complex 2 with a large
excess of NaBH4 results in the formation of an equilib-
rium mixture of 2 and 2 equiv of fac-[PtHMe3(bu2bpy)]
(3) (Scheme 2). Attempts to isolate 3 were unsuccessful,
since workup of the reaction mixtures leads to reversion
to 2 as the excess borohydride is removed. Under the
strongly basic conditions of its formation, the complex
3 decomposes slowly with precipitation of metallic
platinum, but 3 survives for about a 1 at room temper-
F igu r e 2. Thermogravimetric analysis (TGA) curve show-
ing the thermal decomposition of [Pt2(µ-H)Me6(bu2bpy)2]-
SO3CF3 (2).
stable to reductive elimination of methane since at no
time during the synthesis of 3 is [PtMe2(bu2bpy)] (the
reductive elimination product) produced.11 [PtMe2(bu2-
bpy)] is stable to NaBH4, so its absence in the reaction
mixture confirms the stability of 3 to reductive elimina-
tion of CH4. Complex 2 is stable in chlorinated solvents
for several days at room temperature after which it
slowly decomposes to fac-[PtClMe3(bu2bpy)] (4) (see
later). Room-temperature solutions of complex 2 in
nonchlorinated solvents are indefinitely stable and only
start to decompose (precipitating metallic platinum) at
temperatures in excess of 90 °C (toluene solution). The
solid-state decomposition of complex 2 was studied by
thermogravimetric analysis (TGA). A typical TGA plot
is shown in Figure 2 and confirms that 2 is very
resistant to reductive elimination. Complex 2 is stable
to ca. 175 °C after which it undergoes a clean 8% mass
loss. This mass loss corresponds approximately to
elimination of all methyl and hydride ligands. The
gaseous products of this elimination were analyzed by
GC-MS and were found to be composed of mainly CH4
and traces of C2H6. Complex 2 undergoes a further
decomposition between ca. 325 °C and ca. 950 °C to
ultimately leave metallic platinum (33% mass residue).
The only other TGA analysis of an alkyl(hydrido)-
platinum(IV) complex was of [PtHMe2(Tp′)] [Tp′ )
hydridotris(3,5-dimethylpyrazolyl)borate].1b It was found
that this complex decomposes at 190 °C, to give uni-
dentified products. Recently it was shown that a
similiar complex, [PtHMe2{(pz)3BH}] [(pz)3BH ) tris-
(pyrazol-1-yl)borate] decomposes at 140 °C in toluene
solution to form metallic platinum and CH4.1c No solid-
state decomposition studies of this complex have been
reported.
1
ature and was readily characterized by H NMR spec-
troscopy (acetone-d6). Again, the two equivalant bipy-
ridine moieties of the bu2bpy give rise to three aromatic
and one tert-butyl resonance. The methylplatinum
resonances appear in a 2:1 intensity ratio at δ ) 0.75
(trans to bu2bpy) and -0.79 (trans to H) with 2J (PtH)
) 66.0 and 43.0 Hz, respectively (Table 1). Note that
the methyl group trans to the hydrido ligand has a very
low coupling constant to 195Pt (43.0 Hz), which is
significantly smaller than that of the methylplatinum
ligand trans to the bridging hydride in complex 2
[2J (PtH) ) 65.9 Hz] but is similar to that of the mutually
trans methylplatinum ligands in [PtMe4(NN)] [2J (PtH)
) 44 Hz; NN ) bpy, bu2bpy]. Thus the terminal hydrido
ligand in complex 3 has a stronger trans influence than
the bridging hydride in 2. The Pt-H ligand resonates
at δ ) -7.0 with 1J (PtH) ) 805 Hz. This resonance
appears as a 1:4:1 multiplet due to coupling to 195Pt,
thus proving the presence of a terminal Pt-H group.
This coupling constant is approximately twice the
magnitude of that found in 2, which is reasonable since
the s-electron density of the hydride is shared between
two platinum centers in 2. Nevertheless, the value of
1J (PtH) for complex 3 is still significantly smaller than
1
that of [PtH(X)Me2(bu2bpy)] (X ) Cl, Br, I; J (PtH) )
1589.7, 1630.5, 1655.5 Hz, respectively) again illustrat-
ing the trans-effect of the trans methyl ligand.1d It is
the strong σ-donor effect of the trans-methyl group in 3
which is expected to lead to hydridic character of the
Pt-H group in 3 compared to the complexes such as
[PtHClMe2(bu2bpy)]. It is presumably this hydridic
character of the Pt-H bond that leads to the reaction
of 3 with 1 with displacement of SO3CF3 to give the
stable complex 2. This methodology, where a hydridic
M-H group ligates to a second metal, M′, to give a M-H-
M′ system, has been exploited before.10
In all of the above examples of methyl(hydrido)-
platinum(IV) complexes that are resistant to reductive
elimination of CH4 {i.e. [PtHMe2(NN′N′′)] (NN′′N′′ )
Tp′, (pz)3BH), [Pt2(µ-H)Me6(bu2bpy)2]SO3CF3 (2), fac-
[PtHMe3(bu2bpy)] (3)} the ligand trans to hydride can-
not easily dissociate. Presumably, it is the absence of
ligands that can easily dissociate that explains the
extraordinary thermal stability of these complexes.
These results give further support for the proposed
decomposition pathway of alkyl(hydrido)platinum(IV)
complexes in Scheme 1.
Th er m a l Decom p osition Stu d ies of Com p lexes
2 a n d 3. The complex fac-[PtHMe3(bu2bpy)] (3) was not
isolable so a detailed investigation of its thermal stabil-
ity was not possible. Nevertheless, 3 appears to be
(8) Crabtree, R. H. The Organometallic Chemistry of the Transition
Metals, 2nd ed.; J ohn Wiley and Sons: New York, 1994.
(9) For example, see: (a) Brown, M. P.; Keith, A. N.; Manojlovic-
Muir, Lj.; Muir, K. W.; Puddephatt, R. J .; Seddon, K. R. Inorg. Chim.
Acta 1979, 34, L223. (b) Manojlovic-Muir, Lj.; Muir, K. W.; Puddephatt,
R. J .; Seddon, K. R. J . Organomet. Chem. 1979, 179, 479. (c) Brown,
M. P.; Puddephatt, R. J .; Rashidi, M.; Seddon, K. R. J . Chem. Soc.,
Dalton Trans. 1978, 1540.
Isotop ic Exch a n ge w ith in P t(D)CH3 Gr ou p s.
Very recently, it was shown that the protonolysis of the
Pt-C bond by DCl in [PtMe2(tmeda)] (tmeda
)
N,N,N′,N′-tetramethylethylenediamine) proceeds through
(11) Achar, S.; Scott, J . D.; Vittal, J . J .; Puddephatt, R. J . Organo-
metallics 1993, 12, 4592.
(10) Venanzi, L. M. Coord. Chem. Rev. 1982, 43, 251.

Methyl(hydrido)platinum(IV) Complexes
Organometallics, Vol. 16, No. 6, 1997 1213
Sch em e 3
dependent on the acid strength of HX and not the
coordinating ability of the conjugate base (X). For
example, reactions of 2 with HO2CCF3 or HCl are
complete within days, whereas a similar reaction with
HSC6H5 requires several weeks to reach completion, and
thiolate is the strongest ligand for platinum. Qualita-
tively, the rate of these reactions follows the order of
the acid strength, i.e. HCl, HO2CCF3 . HSC6H5, and
not the order of the ligating ability to platinum of the
conjugate base, which would give the sequence SC6H5
> Cl . O2CCF3. This relationship is consistent with a
mechanism that proceeds by slow electrophilic attack
of HX or H+ on 2, giving H2 and 2 equiv of [PtMe3(bu2-
bpy)]+, followed by a rapid coordination of X- to give
the product (Scheme 3). It has been shown that the
electrophilic attack of HX on the tetramethylplati-
num(IV) complexes [PtMe4(NN)] (NN ) 2,2′-bipyridine,
1,10-phenanthroline) to afford CH4 and [PtMe3X(NN)]
proceeds by a similar [SE2(open)] mechanism.2a,12 Note
that electrophiles do not attack a methylplatinum group
of 2, again indicating the relatively low trans-influence
of the bridging hydrido ligand. It is possible that
electrophiles could attack either the Pt-H group or the
MePt group trans to H in complex 3, but since this
compound has not been prepared in pure form, no
studies have been made.
Complexes 4-7 were characterized by comparing
1
their H NMR spectra to those of authentic samples (see
1
Experimental Section). The H NMR spectra of com-
plexes 4-7 each display the expected three sets of
aromatic resonances and one tert-butyl resonance due
to the two equivalent pyridyl groups of the bu2bpy
ligand. The methylplatinum resonances of complexes
4-7 appear in a 2:1 intensity ratio due to the methyl-
platinum ligands trans to bu2bpy and trans to X,
respectively, confirming the presence of the fac-[Pt-
Me3X(bu2bpy)] arrangement. These data are sum-
marized in Table 1 and require no further discussion.
The presence of the Pt-NH3 ligand in complex 6 is
the detectable platinum(IV) deuteride [PtD(Cl)Me2-
(tmeda)] and that deuterium incorporation into the
methylplatinum groups of [PtD(Cl)Me2(tmeda)] occurs
faster than the reductive elimination of methane.1a It
was proposed that this occurred by dissociation of the
chloride ligand to form a five-coordinate complex as in
Scheme 1, followed by easy, reversible formation of a
Pt(CH3D) σ-complex. Since neither fac-[PtDMe3(bu2-
bpy)] (3*) nor [Pt2(µ-D)Me6(bu2bpy)2]SO3CF3 (2*) can
readily undergo ligand dissociation to form the required
five-coordinate intermediate, no isotopic H-D exchange
within PtDMe groups would be expected. This predic-
1
supported by a broad resonance in the H NMR spec-
trum (CD2Cl2) at δ ) 2.30, which is flanked by quarter-
intensity 195Pt satellite signals [2J (PtH) ) ca. 17.5 Hz],
due to the NH3 protons. The ionic nature of 6 is
supported by the presence of a singlet at δ ) -79.0 in
the 19F NMR spectrum (CD2Cl2) attributed to the SO3-
CF3 anion.
tion was upheld; for example, both the H and H{1H}
NMR spectra of 2* showed the absence of deuterium
incorporation into the MePt groups or of H into the PtD
groups, even after several days in solution. This result
gives strong support to the theory that these isotopic
exchange reactions occur via the five-coordinate inter-
mediate [PtHMe2(bu2bpy)]+.
Rea ction of [P t2(µ-H)Me6(bu 2bp y)2]SO3CF 3 (2)
w ith Electr op h ilic Rea gen ts. The reaction of com-
plex 2 with an excess of HX (HX ) HCl, HO2CCF3,
NH4+, HSC6H5) in acetone-d6 solution affords either 2
equiv of fac-[PtClMe3(bu2bpy)] (4), fac-[PtMe3(O2CC-
F3)(bu2bpy)] (5), and fac-[Pt(NH3)Me3(bu2bpy]SO3CF3
(6) or 1 equiv of [Pt2Me6(µ-SC6H5)(bu2bpy)2]SO3CF3 (7),
respectively (Scheme 3). No reaction of HX with the
methylplatinum ligands of 2 was observed, and the fac-
[PtMe3] unit remained intact in all experiments. These
reactions proceed very slowly and take several days to
reach completion, perhaps due to a combination of the
steric protection of the bridging hydride provided by the
bu2bpy ligands and the relatively low hydridic nature
of 2 (see earlier). The rates of these reactions are highly
1
2
In addition to the expected methylplatinum and tert-
butyl resonances, the 1H NMR spectrum (acetone-d6)
of complex 7 displays three sets of resonances at δ )
6.55, 6.11, and 5.43 for the para-, meta-, and ortho-
protons of the Pt-C6H5 ligand, respectively. No 195Pt
satellite signals were observed. Integration of reso-
nances due to the protons of the SC6H5 ligand and the
[PtMe3(bu2bpy)] unit shows that these units are present
in a 1:2 ratio, suggesting the presence of a bridging
SC6H5 ligand (Table 1). The 19F NMR spectrum (acetone-
d6) shows a singlet at -79.0 due to the SO3CF3 anion,
supporting the ionic nature of 7. Treatment of 2 with
1 equiv of HSC6H5 quantitatively gives complex 7,
strongly supporting the presence of a (µ-SC6H5) ligand:
a complex with a terminally bound SC6H5 ligand would
require 2 equiv of HSC6H5 to fully react with 2. The
connectivity in 2 has been confirmed by a preliminary
X-ray crystal structure determination, but the complex
(12) Kondo, Y.; Ishikawa, M.; Ishihara, K. Inorg. Chim. Acta 1996,
241, 81.

1214 Organometallics, Vol. 16, No. 6, 1997
Hill et al.
bine with [PtMe3(bu2bpy)]+ to give 7. A similar situa-
tion most certainly arises when 1 is reacted with
HSC6H5 to give the stable complex 7 (see Experimental
Section). Presumably, 1 initially reacts with HSC6H5
to give 9 which then subsequently reacts with additional
1 by displacement of SO3CF3 to give 7. The feasibility
of the latter step in this proposed mechanism was
confirmed by an independent reaction in which a THF
solution of 9 was treated with 1 equiv of complex 1,
immediately producing complex 7 (Scheme 3). Alter-
natively, the reaction of HSC6H5 with [PtMe4(bu2bpy)]
gives 9 and, since there is no readily available source
of [PtMe3(bu2bpy)]+, the reaction proceeds no further.
Complex 2 did not react with other electrophiles such
as [Au(SO3CF3)PPh3] and decomposed to fac-[PtMe3(SO3-
CF3)(bu2bpy)] (1) upon treatment with [Hg(SO3CF3)2].
Unsaturated reagents such as acetylene and dimethyl
acetylenedicarboxylate did not react with 2 even after
several days in THF solution.
Rea ction of [P t2(µ-H)Me6(bu 2bp y)2]SO3CF 3 (2)
w ith Nu cleop h ilic Rea gen ts. Reaction of complex 2
with a large excess of NaBH4 results in the formation
of an equilibrium mixture of 2 and 2 equiv of fac-
[PtHMe3(bu2bpy)] (3). However, this is not a viable
method to synthesize 3 because, under these strongly
basic conditions, both complexes slowly decompose with
precipitation of metallic platinum. In addition, hydro-
lytic workup of the reaction mixture leads to decomposi-
tion of 3. Because of this, a detailed investigation of
the reaction chemistry of complex 3 has not been
possible. Nevertheless, this suggested that the reaction
of complex 2 with a more innocent nucleophile (Nu)
would yield 1 equiv of 3 and 1 equiv of fac-[PtMe3-
(Nu)(bu2bpy)]. Under these milder conditions, complex
3 should be more stable, potentially allowing a more
thorough investigation of 3 to take place.
F igu r e 3. Structure of [Pt2(µ-SC6H5)Me6(bu2bpy)2]+ (7)
obtained from molecular modeling calculations. The hy-
drogen atoms have been omitted for clarity.
diffracted weakly and the the atoms were not accurately
located. A molecular modeling study was performed for
the [Pt2(µ-SC6H5)Me6(bu2bpy)2]+ cation, and the pre-
dicted structure, shown in Figure 3, is very close to that
determined crystallographically. The syn-syn arrange-
ment of the bu2bpy-SC6H5-bu2bpy ligands in 7 is
similar to that observed for the two bu2bpy ligands in 2
(Figure 1). By the same argument put forth for 2, this
arrangement in 7 presumably is a result of a π-stacking
phenomenon between the aromatic rings of the bu2bpy
and SC6H5 ligands.
Interestingly, the tetramethylplatinum(IV) complex
[PtMe4(bu2bpy)] (8) reacts with HSC6H5 to give not
complex 7 but fac-[PtMe3(SC6H5)(bu2bpy)] (9) (Scheme
3).12 No 9 was produced in the reaction of HSC6H5 with
This prediction was partially upheld; for example the
reaction of 2 with excess PPh3 in refluxing acetone-d6
solution initially produces 1 equiv of 3 and 1 equiv of
fac-[PtMe3(PPh3)(bu2bpy)]SO3CF3 (10). However, the
reaction is exceedingly slow, requiring several weeks to
reach completion, and a method to separate complex 3
from 10 and some byproducts formed over the long
reaction period has not been found. This experiment
clearly indicates that 3 is stable in the absence of
electrophiles, and it should be isolable as a pure
compound if a better synthetic method can be found.
1
2. The H NMR spectrum (acetone-d6) of 9 shows three
sets of aromatic resonances and one tert-butyl resonance
due to the bu2bpy ligand. The methylplatinum reso-
nances appear in the expected 2:1 intensity ratio for the
Pt-Me ligands trans to bu2bpy [δ ) 1.09, 2J (PtH) ) 70.6
2
Hz] and trans to SC6H5 [δ ) 0.15, J (PtH) ) 63.4 Hz],
respectively. The value of 2J (PtH) for the methylplati-
num ligand trans to SC6H5 in complex 9 (63.4 Hz) is
significantly smaller than that in complex 7 (69.3 Hz).
Thus the terminal SC6H5 ligand in 9 has a larger trans
influence than the (µ-SC6H5) ligand in 7. This is as
expected since the available s-electron density at S must
be shared between the two platinum atoms in 7 and only
one in 9. The para-, meta-, and ortho-protons of the Pt-
SC6H5 ligand resonate at δ ) 6.56, 6.35, and 6.32,
respectively. Again, no 195Pt satellite signals were
observed. Integration of the signals in the 1H NMR
spectrum confirms a terminal SC6H5 ligand as the
[PtMe3(bu2bpy)] unit and the SC6H5 ligand appear in a
1:1 ratio.
1
Complex 10 was characterized by comparing the H
NMR spectrum with that of an authentic sample
synthesized from fac-[PtMe3(SO3CF3)(bu2bpy)] and PPh3.
The 1H NMR spectrum (acetone-d6) of 10 shows one tert-
butyl and three sets of aromatic resonances of the bu2-
bpy ligand. The methylplatinum resonances appear in
the expected 2:1 intensity ratio for the Pt-Me ligands
trans to bu2bpy [δ ) 1.33, 2J (PtH) ) 67.5 Hz] and trans
to PPh3 [δ ) 0.52, 2J (PtH) ) 59.8 Hz], respectively
(Table 1). These values of 2J (PtH) are typical for
methylplatinum(IV) ligands trans to bu2bpy and PPh3,
respectively.4 Both methylplatinum signals show coup-
ling to 31P [3J (PH) ) ca. 7.4 Hz]. The 31P{1H} NMR
spectrum (acetone-d6) of 10 shows a singlet at δ ) -2.0
with quarter-intensity 195Pt satellite signals [1J (PtP) )
994 Hz].
The fact that HSC6H5 reacts with 8 to give the
terminal SC6H5 complex (9) but reacts with either 1 or
2 to give the (µ-SC6H5) complex (7) is fully explained in
the mechanism proposed in Scheme 3. For example, if
this mechanism is correct, reaction of 2 with 1 equiv of
HSC6H5 would yield 1 equiv of 9 and 1 equiv of
[PtMe3(bu2bpy)]+. Complex 9 would then rapidly com-
Other nucleophiles such as halide, hydroxide, P(OMe)3,
and CO were even less reactive than PPh3, producing
no reaction with 2 even after several weeks in refluxing

Methyl(hydrido)platinum(IV) Complexes
Organometallics, Vol. 16, No. 6, 1997 1215
Sch em e 4
trum (acetone-d6) of complex 12 displays six sets of
aromatic resonances and one tert-butyl resonance sug-
gesting inequivalent pyridyl groups of the bu2bpy ligand.
This supports the mer-arrangement of the three chloride
ligands of complex 12 and rules out the alternative
isomer {fac-[PtCl3Me(bu2bpy)]} in which the pyridyl
groups would be equivalent. The methylplatinum ligands
of complexes 11 and 12 resonate at uncharacteristically
high frequencies (δ ) 1.85 and 2.69, respectively), and
this is caused by a deshielding effect of the neighboring
electronegative Cl atoms.
Con clu sion s
The new methyl(hydrido)platinum(IV) complexes
[Pt2(µ-H)Me6(bu2bpy)2]SO3CF3 (2) and fac-[PtHMe3(bu2-
bpy)] (3) are thermally stable to reductive elimination
of CH4 and to isotopic exchange within Pt(D)CH3
groups. This gives strong support to the theory that
both reactions proceed through a common, five-coordi-
nate intermediate [PtHMe2(bu2bpy)]+. Complex 2 ex-
hibits only moderate reactivity to a variety of reagents
with all reactions occurring at the µ-hydrido ligand. This
behavior of 2 is due to a combination of the steric
protection of the hydrido ligand by bu2bpy and the
reduced hydridic nature of 2.
acetone. The stability of complex 2 to nucleophilic
attack precludes this methodology as a suitable means
of producing 3.
Rea ction of [P t2(µ-H)Me6(bu 2bp y)2]SO3CF 3 (2)
w ith CCl4. The reaction of complex 2 with excess CCl4
gives fac-[PtClMe3(bu2bpy)] (4), [PtCl2Me2(bu2bpy)] (11),
and mer-[PtCl3Me(bu2bpy)] (12) in a 1.0:0.8:0.2 ratio
(Scheme 4), and methane is also formed. This reaction
is slow and takes several days to reach completion. Most
transition-metal hydrides react with CCl4 by a free-
radical mechanism to give the corresponding metal
chloride and CHCl3.8 The reaction of 2 with CCl4 does
not produce CHCl3, and a possible explanation for this
is presented in the following mechanism. We propose
that complex 2 reacts with CCl4 by an electron-transfer
mechanism to give CCl4•- and 2•+ with further reaction
Exp er im en ta l Section
Gen er a l P r oced u r es. All reactions were performed under
a N2 atmosphere using standard Schlenk techniques, unless
otherwise stated. All solvents were freshly distilled, dried, and
degassed prior to use. CCl4 was refluxed over P4O10 and
distilled prior to use. NMR spectra were recorded using a
Varian Gemini spectrometer (1H at 300.10 MHz, 19F at 282.32
2
MHz, 31P at 121.44 MHz, 195Pt at 42.99 MHz, and H at 30.70
MHz). Chemical shifts are reported in ppm with respect to
TMS (1H and 2H), CFCl3 (19F), H3PO4/D2O (31P), or K2[PtCl4]/
•
2
D2O (195Pt). The 1H, H, 19F, 31P, and 195Pt NMR spectra are
to give CCl3 , fac-[PtClMe3(bu2bpy)] (4), and fac-[PtH-
Me3(bu2bpy)]+•. This accounts for the 1 equiv of 4
present in the product mixture. The fate of the radical
ion fac-[PtHMe3(bu2bpy)]+• is uncertain, but presumably
it undergoes reductive elimination of methane to give
[PtMe2(bu2bpy)]+• before it can further react with CCl4.
The evolution of CH3D (with no CH4) was confirmed by
1H NMR spectroscopy in a similar reaction using [Pt(µ-
D)Me6(bu2bpy)2]SO3CF3 (2*). The remaining products,
[PtCl2Me2(bu2bpy)] (11) and mer-[PtCl3Me(bu2bpy)] (12),
could then be formed by reaction of [PtMe2(bu2bpy)]+•
with CCl4. Only one methylplatinum ligand is present
in 12, and so its formation requires cleavage of a
methylplatinum bond at this stage. It is not possible
to determine how this happens, but the use of CCl4 as
a source of chlorine in oxidative addition is not unex-
pected.
Complexes 11 and 12 were characterized by compar-
ing the 1H NMR spectra to those of the authentic
samples prepared by the trans oxidative addition of Cl2
to [PtMe2(bu2bpy)] and [PtClMe(bu2bpy)], respectively
(see Experimental Section).
The 1H NMR spectrum (acetone-d6) of complex 11
displays one methylplatinum resonance [δ ) 1.85,
2J (PtH) ) 69.5] and three sets of bu2bpy aromatic
resonances (Table 1). This value of 2J (PtH) is consistant
with a methylplatinum(IV) ligand trans to bu2bpy.
These data support the proposed stereochemistry for 11
in which the chloride ligands are mutually trans and
rules out all alternative isomers. The 1H NMR spec-
referenced to the residual protons of the deuterated solvents
or to deuterated solvents, CFCl3, H3PO4/D2O, or K2[PtCl4]/D2O
contained in a coaxial insert, respectively. IR spectra (Nujol
mull) were recorded in the range 4000-400 cm-1 using a
Perkin-Elmer 2000 FT-IR instrument. Elemental analyses
were determined by Guelph Chemical Laboratories, Guelph,
Canada. Thermogravimetric (TGA) studies were performed
using a Perkin-Elmer TGA 7 thermogravimetric analyzer
equipped with a Perkin-Elmer TAC 7/DX thermal analysis
controller. Samples for TGA analysis were heated in platinum
pans under a N2 atmosphere in the range 20-1000 °C at a
rate of 20 °C/min. Molecular mechanics calculations were
performed using the CAChe version 3.8 software package
employing MM2 force-field parameters and a conjugate gradi-
ent optimization method.
The complexes [PtMe2(bu2bpy)],11 [PtMeCl(bu2bpy)],14 and
[Pt2Me8(µ-SMe2)2]15 were synthesized according to literature
procedures. The syntheses for complexes fac-[PtClMe3(bu2-
bpy)] (4), fac-[PtIMe3(bu2bpy)], fac-[PtMe3(O2CCF3)(bu2bpy)]
(5), [PtMe4(bu2bpy)] (8), and fac-[PtMe3(SC6H5)(bu2bpy)](9) are
modified versions of those published for the bpy (bpy ) 2,2′-
bipyridine) analogues.2a,16
P r ep a r a tion of Com p lexes. fa c-[P tMe3(SO3CF 3)(bu 2-
bp y)] (1). To a suspension of [PtMe2(bu2bpy)] (1.73 g, 3.51
mmol) in diethyl ether (40.0 mL) was added MeOSO2CF3
(13) For the analogous reaction with [PtMe4(bpy)] see ref 2a.
(14) Rendina, L. M.; Vittal, J . J .; Puddephatt, R. J . Organometallics
1995, 14, 1030.
(15) Lashanizadehgan, M.; Rashidi, R.; Hux, J . E.; Puddephatt, R.
J .; Ling, S. S. M. J . Organomet. Chem. 1984, 269, 317.
(16) Clegg, D. E.; Hall, J . R.; Swile, G. A. J . Organomet. Chem. 1972,
38, 1532.

1216 Organometallics, Vol. 16, No. 6, 1997
Hill et al.
(0.400 mL, 3.53 mmol) producing an immediate bright orange
to pale yellow color change. After the solution was stirred
under a N2 atmosphere for 18 h, the solvent was removed in
vacuo to give an off-white powder. Yield: 2.30 g (99%). Anal.
Calcd for C22H33F3N2O3PtS: C, 40.2; H, 5.0; N, 4.2. Found:
C, 40.2; H, 4.8; N, 3.9. 1H NMR in acetone-d6: δ ) 8.90 [d,
2H, 3J (H6H5) ) 5.7 Hz, 3J (PtH) ) ca. 14.0 Hz, H6], 8.80 [d,
atmosphere in the absence of light for 2 h. After filtration of
the mixture through Celite filter-aid, the solvent of the pale-
yellow filtrate was removed to give a yellow powder. Yield:
100 mg (99%). Anal. Calcd for C23H33F3N2O2Pt: C, 44.7; H,
5.0; N, 4.9. Found: C, 44.8; H, 5.3; N, 4.5. 1H NMR in acetone-
d6: δ ) 8.88 [d, 2H, 3J (H6H5) ) 6.0 Hz, 3J (PtH) ) ca. 13.5 Hz,
H6], 8.69 [d, 2H, 4J (H3H5) ) 2.0 Hz, H3], 7.84 [dd, 2H, 4J (H5H3)
4
4
2H, J (H3H5) ) 2.0 Hz, H3], 7.97 [dd, 2H, J (H5H3) ) 2.0 Hz,
t
) 2.0 Hz, 3J (H5H6) ) 6.0 Hz, H5], 1.46 [s, 18H, bu], 1.98 [s,
3J (H5H6) ) 5.7 Hz, H5], 1.49 [s, 18H, tbu], 1.21 [s, 6H, 2J (PtH)
6H, 2J (PtH) ) 67.4 Hz, Pt-Me (trans to bu2bpy)], 0.34 [s, 3H,
2J (PtH) ) 76.4 Hz, Pt-Me (trans to O2CCF3)]. 19F NMR in
acetone-d6: δ ) -74 [s].
2
) 66.5 Hz, Pt-Me (trans to bu2bpy)], 0.64 [s, 3H, J (PtH) )
87.0 Hz, Pt-Me (trans to SO3CF3)]. 19F NMR in acetone-d6:
δ ) -79 [s].
fa c-[P t(NH3)Me3(bu 2bp y)]SO3CF 3 (6). An NH3-saturated
solution (1 atm) of fac-[PtMe3(SO3CF3)(bu2bpy)] (100 mg, 0.152
mmol) in CH2Cl2 (10.0 mL) was stirred for 30 min producing
a pale-yellow to colorless color change. The solvent was
removed in vacuo to give a white powder. The product can be
recrystallized from CH2Cl2/n-pentane to give a white micro-
crystalline solid. Yield: 100 mg (97%). Anal. Calcd for
C22H37F3N3O3PtS: C, 39.2; H, 5.4; N, 6.2. Found: C, 39.1; H,
[P t2(µ-H)Me6(bu 2bp y)2]SO3CF 3 (2). To a solution of fac-
[PtMe3(SO3CF3)(bu2bpy)] (300 mg, 0.456 mmol) in THF (200
mL) was slowly added a solution of NaBH4 (17.3 mg, 0.456
mmol) in THF (100 mL). The resulting amber solution was
stirred under a N2 atmosphere for 18 h. Removal of the solvent
in vacuo gave a dark brown solid. This solid was then
triturated with n-pentane (3 × 50 mL) to give a pale brown
powder from which the product was extracted with CH2Cl2 (60
mL). The CH2Cl2 extract was then filtered through Celite
filter-aid giving a bright-yellow solution. The solvent was
removed in vacuo to afford a yellow powder. Yield: 220 mg
(83%). Anal. Calcd for C43H67F3N4O3Pt2S: C, 44.3; H, 5.8; N,
4.8. Found: C, 44.4; H, 5.7; N, 4.8. 1H NMR in CD2Cl2: δ )
3
5.4; N, 6.5. 1H NMR in CD2Cl2: δ ) 8.70 [d, 2H, J (H6H5) )
6.0 Hz, 3J (PtH) ) ca. 14.0 Hz, H6], 8.25 [d, 2H, 4J (H3H5) ) 2.1
4
3
Hz, H3], 7.70 [dd, 2H, J (H5H3) ) 2.1 Hz, J (H5H6) ) 6.0 Hz,
H5], 2.30 [br s, 3H, J (PtH) ) ca. 17.5 Hz, Pt-NH3], 1.47 [s,
2
18H, bu], 1.04 [s, 6H, 2J (PtH) ) 67.8 Hz, Pt-Me (trans to
t
bu2bpy)], 0.31 [s, 3H, 2J (PtH) ) 71.5 Hz, Pt-Me (trans to
NH3)]. 19F NMR in CD2Cl2: δ ) -79.0 [s].
3
3
8.21 [d, 4H, J (H6H5) ) 6.3 Hz, J (PtH) ) 14.0 Hz, H6], 8.09
[d, 4H, J (H3H5) ) 2.0 Hz, H3], 7.51 [dd, 4H, J (H5H3) ) 1.9
4
4
Hz, 3J (H5H6) ) 6.2 Hz, H5], 1.49 [s, 36H, bu], 0.47 [s, 12H,
t
[P t2Me6(µ-SC6H5)(bu 2bp y)2]SO3CF 3 (7). A solution of fac-
[PtMe3(SO3CF3)(bu2bpy)] (200 mg, 0.304 mmol) and C6H5SH
(32 mL, 0.312 mmol) in CH2Cl2 (6.0 mL) was stirred over
anhydrous K2CO3 for 18 h. This bright-yellow solution was
then filtered through Celite filter-aid. The solvent of the
filtrate was then removed in vacuo yielding a yellow oil which,
after trituration with n-pentane (20.0 mL), gave a bright yellow
powder. Yield: 150 mg (78%). Anal. Calcd for C49H71F3-
N4O3Pt2S2: C, 46.1; H, 5.6; N, 4.4. Found: C, 46.1; H, 5.6; B,
2J (PtH) ) 69.6 Hz, 3J (HH) ) ca. 1.0 Hz, Pt-Me (trans to bu2-
bpy)], 0.13 [s, 6H, 2J (PtH) ) 65.9 Hz, 3J (HH) ) ca. 1.0 Hz,
1
Pt-Me (trans to H)], - 11.7 [s, 1H, J (PtH) ) 442 Hz, Pt-H];
195Pt NMR in THF-d8: δ ) -1238 [d, J (PtH) ) 440 Hz]. 19F
1
NMR CD2Cl2: δ ) -79 [s].
When a similar reaction of fac-[PtMe3(SO3CF3)(bu2bpy)] with
NaBH4 was carried out in THF-d8, monitoring by NMR showed
the presence of both 2 and 3 in solution, the relative concen-
tration of 3 increasing with the amount of NaBH4 added. 1H
NMR in THF-d8: δ ) 8.44 [d, 2H, 4J (H3H5) ) 2.0 Hz, H3], 8.24
3
4.3. 1H NMR in acetone-d6: δ ) 8.56 [d, 4H, J (H6H5) ) 6.0
Hz, 3J (PtH) ) 13.7 Hz, H6], 8.27 [d, 4H, 4J (H3H5) ) 1.9 Hz,
3
4
[d, 2H, J (H6H5) ) 6.0 Hz, H6], 7.64 [dd, 2H, J (H5H3) ) 2.0
4
3
H3], 7.70 [dd, 4H, J (H5H3) ) 1.9 Hz, J (H5H6) ) 5.9 Hz, H5],
Hz, 3J (H5H6) ) 6.0 Hz, H5], 1.52 [s, 18H, bu], 0.01 [s, 6H,
t
6.55 [t, 1H, 3J (HpHm) ) 7.6 Hz, p-SC6H5], 6.11 [dd, 2H,
2J (PtH) ) 65.7 Hz, Pt-Me (trans to bu2bpy)], -0.74 [s, 3H,
3J (HmHp) ) 7.6 Hz, 3J (HmHo) ) 7.6 Hz, m-SC6H5], 5.43 [d, 2H,
2J (PtH) ) 44.0 Hz, Pt-Me (trans to H)], -7.0 [s, 1H, J (PtH)
1
t
3
J (HoHm) ) 7.6 Hz, o-SC6H5], 1.37 [s, 36H, bu], 1.15 [s, 12H,
2J (PtH) ) 69.3 Hz, Pt-Me (trans to bu2bpy)], 0.36 [s, 6H,
2J (PtH) ) 69.8 Hz, Pt-Me (trans to SC6H5]. 19F NMR in
acetone-d6: δ ) -79 [s].
) 805 Hz, Pt-H].
fa c-[P tClMe3(bu 2bp y)] (4). A solution of fac-[PtMe3(SO3-
CF3)(bu2bpy)] (100 mg, 0.152 mmol) and LiCl (7.5 mg, 0.177
mmol) in THF (10.0 mL) was stirred under a N2 atmosphere
for 24 h. Removal of the solvent in vacuo gave a pale-yellow
residue from which the product was extracted with CH2Cl2 (2
× 5 mL). The CH2Cl2 extracts were combined and filtered
[P tMe4(bu 2bp y)] (8). A solution of [Pt2Me8(µ-SMe2)2] (0.78
g, 1.23 mmol) and bu2bpy (0.66 g, 2.45 mmol) in diethyl ether
(40.0 mL) was stirred for 15 min under a N2 atmosphere. The
solvent was removed from the solution in vacuo to give a
bright-orange powder. Yield: 1.28 g (99%). Anal. Calcd for
through Celite filter-aid to afford
a pale-yellow filtrate.
Removal of the solvent in vacuo gave a yellow powder. Yield:
81 mg (98%). Anal. Calcd for C21H33ClN2Pt: C, 46.4; H, 6.1;
N, 5.2. Found: C, 46.7; H, 5.9; H, 5.1. 1H NMR in acetone-
d6: δ ) 8.79 [d, 2H, 3J (H6H5) ) 5.9 Hz, 3J (PtH) ) ca. 14.0 Hz,
H6], 8.69 [d, 2H, 4J (H3H5) ) 2.0 Hz, H3], 7.84 [dd, 2H, 4J (H5H3)
C
22H36N2Pt: C, 50.5; H, 6.9; N, 5.4. Found: C, 50.6; H, 7.0;
3
H, 5.3. 1H NMR in acetone-d6: δ ) 8.77 [d, 2H, J (H6H5) )
6.0 Hz, 3J (PtH) ) ca. 14.0 Hz, H6], 8.64 [d, 2H, 4J (H3H5) ) 1.7
Hz, H3], 7.72 [dd, 2H, J (H5H3) ) 1.9 Hz, J (H5H6) ) 5.9 Hz,
4
3
H5], 1.49 [s, 18H, bu], 0.84 [s, 6H, J (PtH) ) 72.0 Hz, Pt-Me
(trans to bu2bpy)], 0.65 [s, 3H, 2J (PtH) ) 44.0 Hz, Pt-Me (trans
to Me)].
t
2
t
) 2.0 Hz, 3J (H5H6) ) 5.9 Hz, H5], 1.46 [s, 18H, bu], 1.99 [s,
6H, 2J (PtH) ) 69.7 Hz, Pt-Me (trans to bu2bpy)], 0.36 [s, 3H,
2J (PtH) ) 74.5 Hz, Pt-Me (trans to Cl)].
fa c-[P tMe3(SC6H5)(bu 2bp y)] (9). A solution of [PtMe4(bu2-
bpy)] (70 mg, 0.134 mmol) and C6H5SH (14 mL, 0.14 mmol) in
acetone (5.0 mL) was stirred under a N2 atmosphere for 24 h
producing a yellow solution. Evaporation of the solvent in
vacuo gave a bright-yellow powder. Yield: 82.7 mg (99%).
Anal. Calcd for C27H38N2PtS: C, 52.5; H, 6.2; N, 4.5. Found:
C, 52.6; H, 6.1; H, 4.4. 1H NMR in acetone-d6: δ 8.65 [d, 2H,
3J (H6H5) ) 5.9 Hz, 3J (PtH) ) ca. 13 Hz, H6], 8.26 [d, 2H,
4J (H3H5) ) 2.0 Hz, H3], 7.70 [dd, 2H, 4J (H5H3) ) 2.0 Hz,
3J (H5H6) ) 5.9 Hz, H5], 6.56 [m, 1H, p-SC6H5], 6.35 [m, 2H,
fa c-[P t IMe3(bu 2b p y)]. To a solution of [PtMe2(bu2bpy)]
(400 mg, 0.810 mmol) in acetone (20.0 mL) was added an
excess of MeI (ca. 0.25 mL) producing an immediate bright-
orange to pale-yellow color change. The solvent was removed
in vacuo giving a yellow solid. Yield: 514 mg (99%). Anal.
Calcd for C21H33IN2Pt: C, 39.7; H, 5.2; N, 4.4. Found: C, 40.1;
H, 5.4; N, 4.5. 1H NMR in acetone-d6: δ ) 8.87 [d, 2H,
3J (H6H5) ) 5.7 Hz, 3J (PtH) ) ca. 14.5 Hz, H6], 8.70 [d, 2H,
4J (H3H5) ) 1.8 Hz, H3], 7.82 [dd, 2H, 4J (H5H3) ) 1.8 Hz,
3J (H5H6) ) 5.7 Hz, H5], 1.47 [s, 18H, tbu], 1.42 [s, 6H, 2J (PtH)
t
2
m-SC6H5], 6.32 [m, 2H, o-SC6H5], 1.43 [s, 18H, bu], 1.09 [s,
) 70.6 Hz, Pt-Me (trans to bu2bpy)], 0.54 [s, 3H, J (PtH) )
6H, 2J (PtH) ) 70.6 Hz, Pt-Me (trans to bu2bpy)], 0.15 [s, 3H,
2J (PtH) ) 63.4 Hz, Pt-Me (trans to SC6H5].
73.5 Hz, Pt-Me (trans to I)].
fa c-[P tMe3(O2CCF 3)(bu 2bp y)] (5). A solution of fac-
[PtIMe3(bu2bpy)] (103 mg, 0.162 mmol) and AgO2CCF3 (35.8
mg, 0.162 mmol) in CH2Cl2 (10.0 mL) was stirred under a N2
fa c-[P tMe3(P P h 3)(bu 2bp y)]SO3CF 3 (10). A solution of
fac-[PtMe3(SO3CF3)(bu2bpy)] (100 mg, 0.152 mmol) and PPh3

Methyl(hydrido)platinum(IV) Complexes
Organometallics, Vol. 16, No. 6, 1997 1217
Ta ble 3. Cr ysta llogr a p h ic Deta ils for 2‚THF
Cr ysta l Str u ctu r e An a lysis of [P t2(µ-H)Me6(bu 2bp y)2]-
SO3CF 3‚1.0THF . Large yellow platelike crystals were ob-
tained from a mixture of THF and n-pentane by slow diffusion
method. A large plate was cut to the size 0.33 × 0.27 × 0.23
mm, mounted inside a Lindemann capillary tube, flame sealed,
and used for the diffraction experiments. The diffraction
experiments were carried out using a Siemens P4 diffracto-
meter with XSCANS software package using graphite-mono-
chromated Mo KR radiation at 24 °C.17 The cell constants were
obtained by centering 25 high-angle reflections (11.2 e 2θ e
25.0°). A total of 8085 reflections were collected in the θ range
1.66-23.03° (-1 e h e 51, -1 e k e 14, -19 e l e 19) in
ω-scan mode at variable scan speeds (2-30 deg/min). Back-
ground measurements were made at the ends of the scan
range. Four standard reflections were monitored at the end
of every 296 reflections. An empirical absorption was applied
to the data on the basis of ψ-scan techniques. The minimum
and maximum transmission factors are 0.258 and 0.406. The
systematic absences indicated that the space group could be
either Cc or C2/c. For Z ) 8, in the monoclinic system, the
space group C2/c was chosen. The correctness of the choice of
the space group was confirmed by successful solution and
refinement of the structure. SHELXTL programs were used
for data processing and the least-squares refinements on F2.18
All the Pt and the carbon atoms of the methyl and tert-butyl
atoms were refined anisotropically. Isotropic thermal param-
eters were refined for the atoms in the bipyridyl rings. The
methyl atoms of the tert-butyl carbon C(6c) were found to be
disordered. Two orientations were resolved (0.6/0.4). Common
isotropic thermal parameters were refined for each of these
models. Soft constraints were applied for all the tert-butyl
empirical formula
fw
C47H75F3N4O4Pt2S
1239.35
temp
24 °C
wavelength
cryst system
space group
unit cell dimens
0.71073 Å
monoclinic
C2/c
a ) 47.307(7) Å, b ) 12.758(1) Å,
c )18.186(3) Å, â ) 105.0(1)°
10602(3) Å3
V
Z
8
Dcalcd
abs coeff
1.553 g‚cm-3
5.364 mm-1
indepdt reflcns
refinement method
data/restraints/params
goodness-of-fit (GooF)a on F2
final R indices [I > 2 σ(I)]
R indices (all data)a
7257 (R(int) ) 0.0400)
full-matrix least-squares on F2
4343/342/429
1.007
R1 ) 0.0602, wR2 ) 0.1312
R1 ) 0.1195, wR2 ) 0.1643
R1 ) Σ(||Fo| - |Fc||)/Σ|Fo|. wR2 ) [Σw(Fo - Fc2)2/ΣwFo4]1/2
.
a
2
GooF ) [Σw(Fo - Fc2)2/(n - p)]1/2, where n is the number of
reflections and p is the number of parameters refined.
2
(40 mg, 0.152 mmol) in CH2Cl2 (10.0 mL) was stirred under a
N2 atmosphere for 3 h. The solvent was removed in vacuo
giving a white powder. Yield: 139 mg (99%). Anal. Calcd
for C40H48F3N2O3PPtS: C, 52.2; H, 5,3; N, 3.0. Found: C, 52.0;
H, 5.0; N, 2.6. 1H NMR in acetone-d6: δ ) 8.65 [d, 2H,
4J (H3H5) ) 2.0 Hz, H3], 8.42 [d, 2H, 3J (H6H5) ) 6.3 Hz, 3J (PtH)
4
3
) ca. 13.5 Hz, H6], 7.75 [dd, 2H, J (H5H3) ) 2.0 Hz, J (H5H6)
) 6.2 Hz, H5], 7.44 [m, 3H, Pt-PPh3], 7.31 [m, 6H, Pt-PPh3],
7.09 [m, 6H, Pt-PPh3], 1.44 [s, 18H, tbu], 1.33 [s, 6H, 2J (PtH)
) 67.5 Hz, 3J (PH) ) 7.4 Hz, Pt-Me (trans to bu2bpy)], 0.52
-
2
3
groups using the option SADI. The SO3CF3 anion was
[s, 3H, J (PtH) ) 59.8 Hz, J (PH) ) 7.3 Hz, Pt-Me (trans to
PPh3)]. 31P{1H} NMR in acetone-d6: δ ) -2.0 [s, 1J (PtP) )
994 Hz]. 19F NMR in acetone-d6: δ ) -79.0 [s].
disordered. Two disorder models (occupancy 0.6/0.4) were
included in the least-squares refinements. The geometry of
the two models was idealized using the option DFIX. Common
isotropic thermal parameters were refined for each model. A
region of electron density was found in the difference Fourier,
and this was recognized to be tetrahydrofuran (THF) having
three different orientations in the crystal lattice. Again, each
model was idealized and included in the least-squares refine-
ments. Common isotropic thermal parameters were refined
for each model. No attempt was made to locate all the
hydrogen atoms. However, the hydrogen atom near the Pt
atoms was located successfully in the difference Fourier. Only
the positional parameter was refined with a soft constraint
imposed that the Pt-H be equal using SADI, and temperature
factor was fixed at U ) 0.05 Å2. All the hydrogen atoms were
placed in calculated ideal positions for the purpose of structure
factor calculations only. In the final least-squares refinement
cycles on F2, the model converged at R1 ) 0.0602, wR2 )
[P tCl2Me2(bu 2bp y)] (11). A Cl2-saturated solution (1 atm)
of [PtMe2(bu2bpy)] (100 mg, 0.203 mmol) in CH2Cl2 (5.0 mL)
was stirred for 5 min producing an immediate bright-orange
to yellow color change. The solvent was removed in vacuo
giving a pale yellow powder. Yield: 114 mg (99%). Anal.
Calcd for C20H30Cl2N2Pt: C, 42.6; H, 5.4; N, 5.0. Found: C,
42.4; H, 5.3; N, 4.8. 1H NMR in acetone-d6: δ 8.84 [d, 2H,
3J (H6H5) ) 5.9 Hz, 3J (PtH) ) ca. 13 Hz, H6], 8.74 [d, 2H,
4J (H3H5) ) 1.9 Hz, H3], 7.90 [dd, 2H, 4J (H5H3) ) 1.9 Hz,
3J (H5H6) ) 5.9 Hz, H5], 1.85 [s, 6H, 2J (PtH) ) 69.5 Hz, Pt-
t
Me], 1.46 [s, 18H, bu].
m er -[P tCl3Me(bu 2bp y)] (12). A Cl2-saturated solution (1
atm) of [PtClMe(bu2bpy)] (100 mg, 0.194 mmol) in CH2Cl2 (5.0
mL) was stirred for 20 min. The solvent was removed in vacuo
giving a bright-yellow powder. Yield: 113 mg (99%). Anal.
Calcd for C19H27Cl3N2Pt: C, 39.0; H, 4.6; N, 4.8. Found: C,
39.3; H, 4.7; N, 4.6. 1H NMR in acetone-d6: δ 9.34 [d, 1H,
3J (H6H5) ) 6.0 Hz, 3J (PtH) ) 12.0 Hz, H6], 8.84 [d, 1H,
0.1312, and Goof ) 1.007, for 4343 observations with Fo
g
4σ(Fo) and 429 parameters, and R1 ) 0.1195 and wR2 )
0.1643, for all 7257 data. In the final difference Fourier
synthesis, the electron density fluctuates in the range 1.094
to -0.882 e Å-3. The mean shift/esd and the maximum shift
3
4J (H3H5) ) 2.0 Hz, H3], 8.82 [d, 1H, J (H6′H5′) ) 6.0 Hz, H6′],
8.81 [d, 1H, 4J (H3′H5′) ) 2.0 Hz, H3′], 8.08 [dd, 1H, 4J (H5H3) )
3
4
2.0 Hz, J (H5H6) ) 6.0 Hz, H5], 7.98 [dd, 1H, J (H5′H3′) ) 2.0
3
2
in the final cycles are 0.005 and -0.090, respectively. A
secondary extinction correction was refined to be 0.000 076(13).
Hz, J (H5′H6′) ) 6.0 Hz, H5′], 2.69 [s, 3H, J (PtH) ) 68.0 Hz,
Pt-Me], 1.50 [s, 9H, bu], 1.49 [s, 9H, bu].
t
t
Rea ction s of 2 w ith Acid s. NMR solutions (acetone-d6)
of 2 and 2 equiv of either HCl (obtained from Me3SiCl and
H2O), HO2CCF3, or HSC6H5 were monitored by 1H NMR
spectroscopy over the period of several days. The extent of
reaction was measured by integrating the methylplatinum
resonances of 2 relative to those of 4, 5, or 7, respectively. The
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal
data, complete positional and thermal parameters of the non-
hydrogen atoms, bond distances and angles, hydrogen atom
coordinates, selected weighted least-squares planes, and se-
lected dihedral angles for 2‚THF (14 pages). Ordering infor-
mation is given on any current masthead page.
qualitative rate follows the order of HCl ≈ HO2CCF3
.
HSC6H5.
OM960975L
Rea ction of 2 w ith CCl4. An NMR solution (acetone-d6)
of 2 and a 4-fold excess of CCl4 was monitored by 1H NMR
spectroscopy. The reaction was complete after ca. 4 days
giving 4, 11, and 12 in a 1.0:0.8:0.2 product ratio. Chloroform
(17) XSCANS version 2.1; Siemens Analytical X-Ray Instruments
Inc.: Madison, WI, 1994.
(18) SHELXTL Software version 5.0; Siemens Analytical X-Ray
Instruments Inc.: Madison, WI, 1994.
1
was not detected by H NMR spectroscopy.