Novel T-shaped 14-electron platinum(II) complexes stabilized by one agostic interaction

Article abstract of DOI:10.1002/anie.200390035

The stereoelectronic properties of the PR₂(2,6-Me₂C₆H₃) (R=Ph, Cy) ligand can be used to stabilize an unprecedented class of 14-electron platinum(II) complexes. The X-ray analysis of the cyclometalated cyclohexyl derivative reveals an agostic interaction between the Pt center and an o-methyl moiety (see picture). The fast and reversible formation of three-coordinate platinum-hydrido complexes occurs by reaction with H₂, and is achieved through the cleavage of a platinum-carbon bond.

Full text of DOI:10.1002/anie.200390035

Angewandte
Chemie
F(000) ¼ 5012, m(MoKa) ¼ 0.714 mmÀ1
. Crystal data for 8
14-Electron Platinum(II) Complexes
(C88H164Cr7F8NNiO32; Mr ¼ 2316.20): dark-green plate, mono-
clinic, space group P21/n, a ¼ 26.067(2), b ¼ 20.3010(17), c ¼
27.098(2) ä, b ¼ 112.258(1)8, V¼ 13271.5(19) ä3, Z ¼ 4, T¼
Novel T-Shaped 14-Electron Platinum(ii)
Complexes Stabilized by One Agostic
Interaction**
120.0(2) K, 1calcd ¼ 1.159 gcmÀ1
,
F(000) ¼ 4876, m(MoKa) ¼
0.700 mmÀ1. Crystal data for 9 (C96H180Cr7F8NNiO32; Mr ¼
2428.41): dark-green plate, orthorhombic, space group Pnma,
a ¼ 23.2504(15),
b ¼ 21.0031(13),
c ¼ 31.451(2) ä,
V¼
Walter Baratta,* Sergio Stoccoro,*
Angelino Doppiu, Eberhardt Herdtweck,
Antonio Zucca, and Pierluigi Rigo
15358.4(17) ä3, Z ¼ 4, T¼ 120.0(2) K, 1calcd ¼ 1.050 gcmÀ1
,
F(000) ¼ 5132, m(MoKa) ¼ 0.608 mmÀ1. Unit cell for 10: dark-
green plate, monoclinic, space group P21/c, a ¼ 25.031(1), b ¼
16.639(1), c ¼ 30.910(1) ä, b ¼ 110.03(1)8. Unit cell for 11: dark-
green plate, monoclinic, space group P21/c, a ¼ 25.061(4), b ¼
16.622(3), c ¼ 30.960(5) ä, b ¼ 110.488(5)8. Unit cell for 12:
dark-green plate, monoclinic, space group P21/c, a ¼ 25.049(2),
b ¼ 16.630(1), c ¼ 30.927(2) ä, b ¼ 110.18(3)8. Unit cell for 13:
dark-green plate, monoclinic, space group P21/c, a ¼ 25.173(7),
b ¼ 16.629(5), c ¼ 31.135(8) ä, b ¼ 111.093(3)8. Compounds 10,
11, 12, and 13 are isostructural with 6. Data were collected on a
Bruker SMART CCD diffractometer (MoKa, l ¼ 0.71069 ä). In
all cases the selected crystals were mounted onto the tip of a
glass pin using Paratone-N oil and placed in the cold flow
(120 K) produced with an Oxford Cryocooling device. Complete
hemispheres of data were collected using w scans (0.38, 30 s/
Three-coordinate 14-electron d8-ML3 complexes, which are
generally transient species generated in situ by ligand disso-
ciation, have received much attention because of their key
role in many stoichiometric and catalytic reactions.[1] Plati-
num(ii) complexes of the form [L2PtR(solvent)]þ, which
contain bidentate nitrogen ligands and a weakly bonded
À
solvent molecule, have been found to be active in alkane C H
activation through the formation of the transient alkane s-
þ
adduct [L2PtR(R’ H)] .[2] Such species have eluded isolation
À
because of the ease of displacement of the alkane moiety by
solvent or anions in solution, and thus, several approaches
have been used to examine their reactivity including the study
of agostic complexes.[3] Orpen and Spencer have described a
[12]
frame). Integrated intensities were obtained with SAINTþ
and corrected for absorption using SADABS.[12] Structure
solution and refinement was performed with the SHELX-
package.[12] The structures were solved by direct methods and
completed by iterative cycles of DF syntheses and full-matrix
least-squares refinement against F2 to give for 4: using 479 pa-
rameters and 55 restraints, wR2 ¼ 0.5006 (12935 unique reflec-
tions), R1 ¼ 0.1806 (11281 reflections with I > 2s(I));for 5: using
299 parameters and 28 restraints, wR2 ¼ 0.2937 (7978 unique
reflections), R1 ¼ 0.0973 (7306 reflections with I > 2s(I));for 6:
using 1204 parameters and 105 restraints, wR2 ¼ 0.1716
(20413 unique reflections), R1 ¼ 0.0804 (17353 reflections with
I > 2s(I));for 7: using 901 parameters and 108 restraints, wR2 ¼
0.3241 (22002 unique reflections), R1 ¼ 0.1140 (13892 reflections
with I > 2s(I));for 8: using 827 parameters and 116 restraints,
wR2 ¼ 0.4806 (30385 unique reflections), R1 ¼ 0.1661 (17629 re-
flections with I > 2s(I));for 9: using 449 parameters and
76 restraints, wR2 ¼ 0.5085 (9688 unique reflections), R1 ¼
0.1780 (7500 reflections with I > 2s(I)). CCDC-191618 191623
contains the supplementary crystallographic data for this paper.
These data can be obtained free of charge via www.ccdc.cam.
ac.uk/conts/retrieving.html (or from the Cambridge Crystallo-
graphic Data Centre, 12, Union Road, Cambridge CB21EZ,
UK;fax: ( þ 44)1223-336-033;or deposit@ccdc.cam.ac.uk).
[10] A. Bencini, D. Gatteschi, EPR of Exchange Coupled Systems,
Springer, Berlin, 1989.
series of b-agostic platinum(ii) complexes of the type
þ
À
À
[Pt(R)(P P)] (P P ¼ chelating diphosphane;R ¼ alkyl),
which are in equilibrium with the corresponding alkene
hydrido derivatives,[4] and which have been viewed as models
for intermediates along the migratory insertion/b-elimination
alkene-polymerization pathway.[3a,4c] The bulky phosphane
PtBu3 has been used to stabilize 14-electron T-shaped
platinum(ii) species of the form trans-[PtH(PtBu3)2]X (X ¼
noncoordinating anion), which have been characterized by
NMR analysis.[5] It is noteworthy that the analogous deriva-
tives bearing PCy3 or PiPr3 moieties led to the four-coordinate
complexes trans-[PtH(PR3)2(solvent)][BArf4] (R ¼ Cy,[6a]
iPr;[6b] Arf ¼ 3,5-(CF3)2C6H3), with dichloromethane as sol-
vent.
[*] Dr. W. Baratta, Prof. P. Rigo
Dipartimento di Scienze e Tecnologie Chimiche
Universit‡ di Udine
Via Cotonificio 108, 33100 Udine (Italy)
Fax: (þ39)0432 558 803
[11] G. M. Smith, J. C. G. Lesurf, R. H. Mitchell, P. C. Riedi, Rev.Sci.
Instrum. 1998, 69, 3924 3931.
E-mail: inorg@dstc.uniud.it
[12] SHELX-PC Package, Bruker Analytical X-ray Systems, Madi-
son, WI, 1998.
Dr. S. Stoccoro, Dr. A. Doppiu, Dr. A. Zucca
Dipartimento di Chimica
Universit‡ di Sassari
Via Vienna 2, 07100 Sassari (Italy)
Fax: þ39 079 229 559
E-mail: stoccoro@ssmain.uniss.it
Dr. E. Herdtweck
Anorganisch-chemisches Institut
Technische Universit‰t M¸nchen
Lichtenbergstrasse 4, 85747 Garching (Germany)
[**] This work was supported by Ministero della Ricerca Scientifica e
Tecnologica (MURST), University of Sassari and the Bayerische
Forschungsstiftung (FORKAT; X-ray equipment).
Supporting information for thisarticle isavailable on the WWW
under http://www.angewandte.org or from the author.
Angew. Chem. Int. Ed. 2003, 42, No. 1
¹ 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1433-7851/03/4201-0105 $ 20.00+.50/0
105

Communications
Among the phosphanes used to stabilize low-coordinated
species, those containing the 2,6-dimethylphenyl group ap-
pear very effective since the o-methyl groups can easily
interact in an agostic fashion. In fact, we have recently
isolated a rare example of a 14-electron ruthenium(ii)
complex [RuCl2{PPh2(2,6-Me2C6H3)}2],[7] which is stabilized
by two agostic interactions. In contrast, employment of the
PPh2(2,6-Me2C6H3) ligand with osmium led to the formation
of complexes containing a tridentate trans-stilbene-type
ligand, which results from the coupling of two o-methyl
methyl group.[7,14] Although the NMR data for complex 4 is
similar to that for 3, no rotation of the 2,6-dimethylphenyl
group occurs at room temperature. The H NMR resonance
of the agostic CH3 group appears at d ¼ 2.70 ppm with
J(H,Pt) ¼ 64.0 Hz, whereas its 13C{1H} NMR signal is shifted
to high field (d ¼ 13.6 ppm) with a remarkably high J(C,Pt)
coupling constant of 191 Hz. The NMR data of 3 and 4 clearly
suggests that rotation of the 2,6-dimethylphenyl group is
affected by the steric requirements of the PR2 (R ¼ Ph, Cy)
moiety, with cyclohexyl substituents leading to a more
hindered rotation than with phenyl substituents.
1
groups and the activation of four C H bonds.[8] We have now
À
found that PR2(2,6-Me2C6H3) ligands (R ¼ Ph, Cy) can be
used to prepare a new class of three-coordinate 14-electron
platinum(ii) complexes;the crystallographic characterization
of the cyclohexyl derivative is reported herein.
To establish the previous formulation with one o-methyl
group close to the metal center, an X-ray diffraction study was
carried out on a single crystal of 4.[15] The representation of
the cation of 4 with some relevant bond lengths and angles is
Treatment of [PtMeCl(cod)] (cod ¼ cyclooctadiene) with
two equivalents of PPh2(2,6-Me2C6H3) in dichloromethane
afforded the trans derivative 1 (84% yield),[9] through the
substitution of cyclooctadiene. Similarly to 1, complex 2[9] was
obtained in 85% yield from the platinum precursor and the
bulky phosphane PCy2(2,6-Me2C6H3) (Scheme 1).
shown in Figure 1;the [BAr f ]À ion is not bound directly to the
4
platinum center.
Complexes 1 and 2 are thermally stable in solution and
show NMR parameters in accordance with those of the trans-
[PtMeX(PR3)2] derivatives.[10] No cis complexes were ob-
served during the formation of 1 and 2, which can be
attributed to the high steric requirement of the phosphanes
employed.[11]
The three-coordinate complexes 3 and 4[12] are obtained in
85 and 76% yield, respectively, by reacting 1 or 2 with
Na[BArf4] in CH2Cl2 at room temperature through the
À
cleavage of an o-methyl C H bond and extrusion of methane
(Scheme 1). The H NMR spectrum of 3 in CD2Cl2 at room
1
temperature shows a resonance at d ¼ 2.35 ppm, with a value
for J(H,Pt) (that is, the coupling constant for the metal
satellite resonances) of 30.3 Hz for two methyl groups. At
À958C this signal splits into two resonances of equal intensity
at d ¼ 2.95 and 1.75 ppm, which indicates that the rotation of
the 2,6-dimethylphenyl group is frozen out. The 13C{1H} NMR
spectrum at 208C displays a signal at d ¼ 22.7 ppm for the
PtCH2 moiety with a large 1J(C,Pt) coupling constant of
840 Hz,[10,13] consistent with a ™very weak∫ ligand trans to the
CH2 group, whereas the resonance for the two methyl groups
is at d ¼ 17.6 ppm with J(C,Pt) ¼ 94 Hz. Upon cooling at
À958C this signal splits into two peaks at d ¼ 22.8 and
9.4 ppm, of which the latter is attributable to the agostic
Figure 1. ORTEP-style drawing of the Pt-centered cation in the solid-
state structure of 4¥0.25 CH2Cl2. Thermal ellipsoids are drawn at the
À
50% probability level. Selected bond lengths[ä] and angles[ 8]: Pt1 P1
À
À
2.3088(9), Pt1 P2 2.3279(9), Pt1 C10 2.088(7), Pt1¥¥¥C40 2.432(6); P1-
Pt1-P2 177.71(3), P1-Pt1-C10 81.91(14), P1-Pt1¥¥¥C40 101.41(12), P2-
Pt1-C10 97.28(14), P2-Pt1¥¥¥C40 79.63(12), C10-Pt1¥¥¥C40 172.94(18),
Pt1-P2-C41 107.21(11).
Scheme 1. Synthesis of 1 4.
106
¹ 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1433-7851/03/4201-0106 $ 20.00+.50/0
Angew. Chem. Int. Ed. 2003, 42, No. 1

Angewandte
Chemie
The crystal structure consists of discrete monomeric units
with the platinum center in a nearly square environment,
coordinated to two trans phosphane groups and an alkyl
group. The coordination sphere is completed by one methyl
group of the 2,6-dimethylphenyl moiety. The Pt1-P2-C41
angle for the 2,6-dimethylphenyl group of 4 is 107.21(11)8 and
is smaller than the equivalent angles for the cyclohexyl
substituents Pt1-P2-C51 (114.57(13)8) and Pt1-P2-C61
(115.11(12)8).[7] The five atoms Pt1, P1, P2, C10, and C40
are almost coplanar, and lie less than ꢀ 0.10 ä from the
mean plane, whereas the 2,6-dimethylphenyl group is bent
complexes of platinum(ii), but are actually three-coordinate
complexes with time-averaged agostic interactions of the four
o-methyl groups. When the solutions containing either 5 or 6
are gently heated (408C) under Ar for a few minutes, the
equilibrium completely shifts to the left as a result of the
deprotonation of an agostic o-methyl group and associated H2
À
extrusion. In the reversible Pt C hydrogenolysis, H2 probably
replaces the agostic o-methyl group, which leads to a transient
cationic dihydrogen-cyclometalated platinum(ii) complex
that may be in equilibrium with the 16-electron platinum(iv)
dihydrido species.[1j,19] Interestingly, Milstein and co-workers
have recently reported the opening of a platinum(ii) metal-
lacycle complex by reaction with dihydrogen, but under
harsher conditions.[20]
À
back from this plane and is hinged about the P2 C40 axis at
an angle of 8.4(2)8 (as defined by the P2-Pt1-C40 and P2-C41-
C42-C40 planes). The Pt1¥¥¥C40 separation (2.432(6) ä) is a
relatively short nonbonding distance, and is longer than the
length reported for b-agostic complexes.[4a b] It is noteworthy
that the hydrogen atoms bonded to C40, which have been
located and refined, are ™tilted∫ away from the metal, a
phenomenon that has been observed in [RuCl2{PPh2(2,6-
Me2C6H3)}2][7] and in some lanthanoid derivatives that contain
the CH(SiMe3)2 ligand.[16] This may indicate an agostic
interaction with the carbon atom providing a strong contri-
bution.
In conclusion, the accessibility of 14-electron platinum(ii)
complexes relies on the use of the bulky ligands PR2(2,6-
Me2C6H3) (R ¼ Ph, Cy) which allow protection against
solvent coordination. Complexes 3 and 4 represent rare
examples of three-coordinate platinum(ii) complexes, char-
acterized both in solution and in the solid state, that undergo a
reversible and facile platinum carbon hydrogenolysis
through loss of the weakly bound o-methyl group. These
complexes may be suitable precursors for new investigations
of the relatively unexplored chemistry of 14-electron plati-
num(ii) complexes.
As a result of the high coordinative unsaturation of 3 and
4, these complexes react with dihydrogen in an equilibrium
reaction in which the hydrido derivatives 5 and 6 are readily
À
formed by heterolytic dihydrogen splitting and Pt C bond
cleavage [Eq. (1)].[17]
Experimental Section
3: Na[BArf4] (298 mg, 0.36 mmol) was added to 1 (300 mg, 0.36 mmol)
dissolved in dichloromethane (20 mL), which afforded the evolution
of methane and a precipitate of NaCl. After filtration of the NaCl, the
solution was evaporated to dryness. The white solid was washed with
cold pentane, filtered, and dried under reduced
pressure. Yield 501 mg (85%). The derivative 4
was prepared by an analogous method (76%
yield).
When a solution of 3 (CD2Cl2, 208C) is treated with
dihydrogen (1 atm), the 31P{1H} NMR spectrum exhibits one
sharp resonance at d ¼ 29.0 ppm with 1J(P,Pt) ¼ 2717 Hz for 5,
in addition to signals for 3 (5:3 molar ratio ¼ 1:4). The
Received: August 26, 2002 [Z50047]
[1] a) J. P. Collman, L. S. Hegedus, J. R. Norton,
R. G. Finke, Principles and Applications of
Organotransition Metal Chemistry, Universi-
ty Science Books, Mill Valley, CA, 1987;
b) J. A. Maguire, W. T. Boese, M. E. Goldman, A. S. Goldman,
Coord.Chem.Rev. 1990, 97, 179;c) A. Vigalok, Y. Ben-David, D.
Milstein, Organometallics 1996, 15, 1839;d) R. Romeo, Com-
ments Inorg.Chem. 1990, 11, 21;e) R. Romeo, M. R. Plutino,
L. I. Elding, Inorg.Chem. 1997, 36, 5909;f) C. D. Tagge, R. D.
Simpson, R. G. Bergman, M. J. Hostetler, G. S. Girolami, R. G.
1H NMR spectrum reveals one signal at d ¼ 2.22 ppm with
J(H,Pt) ¼ 11.3 Hz for the four o-methyl groups and one broad
signal at d ¼ À20.83 for the hydrido ligand with a remarkably
1
high J(H,Pt) coupling constant of 2052 Hz.[18] Similarly to 3,
the reaction of 4 with H2 leads to the formation of complex 6
Nuzzo, J.Am.Chem.Soc.
1996, 118, 2634;g) E. L. Dias, M.
1
(d(31P) ¼ 54.5; J(P,Pt) ¼ 2631 Hz), where 6 and 4 are recov-
Brookhart, P. S. White, Chem.Commun. 2001, 423;h) D. J.
Mindiola, G. L. Hillhouse, J.Am.Chem.Soc. 2001, 123, 4623;i) J.
Cµmpora, E. Gutiÿrrez-Puebla, J. A. LÛpez, A. Monge, P. Palma,
D. del RÌo, E. Carmona, Angew.Chem. 2001, 113, 3753; Angew.
Chem.Int.Ed. 2001, 40, 3641;j) R. J. Puddephatt, Angew.Chem.
2002, 114, 271; Angew.Chem.Int.Ed. 2002, 41, 261.
ered in a molar ratio of 2:1, which indicates that for the
Cy derivative the equilibrium is more shifted to the right. The
1H NMR spectrum of 6 exhibits one signal at d ¼ 2.74 ppm
with J(H,Pt) ¼ 15.0 Hz for the o-methyl groups and one triplet
1
at d ¼ À19.74 ppm (2J(H,P) ¼ 10.0 Hz) with a J(H,Pt) cou-
[2] a) M. W. Holtcamp, J. A. Labinger, J. E. Bercaw, J.Am.Chem.
Soc. 1997, 119, 848;b) L. Johansson, O. B. Ryan, M. Tilset, J.Am.
Chem.Soc. 1999, 121, 1974;c) L. Johansson, M. Tilset, J.Am.
Chem.Soc. 2001, 123, 739.
[3] a) M. Brookhart, M. L. H. Green, L.-L. Wong, Prog.Inorg.
Chem. 1988, 36, 1;b) R. H. Crabtree, D. G. Hamilton, Adv.
pling constant of 2074 Hz. The data is similar to that of the
three-coordinate derivatives [PtH(PtBu3)2]X (X ¼ BF4, PF6,
ClO4, CF3SO3)[5] but differs from that of the related cyclo-
hexyl species [PtH(PCy3)2(L)][BArf4] (L ¼ CD2Cl2 and H2)[6a]
indicating that 5 and 6 are not solvato or dihydrogen[19]
Angew. Chem. Int. Ed. 2003, 42, No. 1
¹ 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1433-7851/03/4201-0107 $ 20.00+.50/0
107

Communications
Organomet.Chem. 1988, 28, 299;c) R. H. Crabtree, Angew.
collection were carried out on a kappa-CCD device (NON-
IUS MACH3) at the window of a rotating anode (NON-
IUS FR591) with graphite-monochromated MoKa radiation
(l ¼ 0.71073 ä). Data collection was performed at 123 K within
the V range of 1.20 < V< 25.358. A total of 81323 reflections
were integrated and corrected for Lorentz and polarization
effects. A correction for absorption effects was applied with the
Chem. 1993, 105, 828; Angew.Chem.Int.Ed.Engl. 1993, 32, 789.
[4] a) N. Carr, B. J. Dunne, A. G. Orpen, J. L. Spencer, J.Chem.Soc.
Chem.Commun. 1988, 926;b) N. Carr, L. Mole, A. G. Orpen, J. L.
Spencer, J.Chem.Soc.Dalton Trans. 1992, 2653; c) L. Mole, J. L.
Spencer, N. Carr, A. G. Orpen, Organometallics 1991, 10, 49.
[5] R. M. Goel, R. C. Srivastava, Can.J.Chem. 1983, 61, 1352.
[6] a) S. S. Stahl, J. A. Labinger, J. E. Bercaw, Inorg.Chem. 1998, 37,
2422;b) M. D. Butts, B. L. Scott, G. J. Kubas, J.Am.Chem.Soc.
1996, 118, 11831.
[7] W. Baratta, E. Herdtweck, P. Rigo, Angew.Chem. 1999, 111,
1733; Angew.Chem.Int.Ed. 1999, 38, 1629.
[8] W. Baratta, E. Herdtweck, P. Martinuzzi, P. Rigo, Organo-
metallics 2001, 20, 305.
DIFABS algorithm (Cmin/max 0.632/0.892). After merging (Rint
¼
0.0338), 26468 (21745: Io > 2s(Io)) independent reflections
remained and all were used to refine 2187 parameters. The
structure was solved by a combination of direct methods and
difference-Fourier syntheses. All nonhydrogen atoms were
refined anisotropically. All 61 hydrogen atom positions for the
Pt1 cation were found in the difference Fourier map calculated
from the model containing all nonhydrogen atoms. The hydro-
gen positions were refined with individual isotropic displace-
ment parameters. All of the other 104 hydrogen atoms were
[9] NMR data for complexes 1 and 2 are provided as Supporting
Information.
[10] F. R. Hartley in Comprehensive Organometallic Chemistry, Vol.
6 (Eds.: G. Wilkinson, F. G. A. Stone, E. W. Abel), Pergamon
Press, Oxford, 1982, p. 471.
placed in calculated positions (dCÀ ¼ 0.95, 0.98, 0.99, 1.00 ä).
H
Isotropic displacement parameters were calculated from the
parent carbon atom (UH ¼ 1.2/1.5¥UC). The hydrogen atoms were
included in the structure factor calculations but not refined. Full-
matrix least-squares refinements in 4 blocks were carried out by
[11] a) G. Alibrandi, M. Cusumano, D. Minniti, L. Monsú Scolaro, R.
Romeo, Inorg.Chem. 1989, 28, 342;b) R. Romeo, G. Alibrandi,
Inorg.Chem. 1997, 36, 4822.
minimizing w(Fo ÀFc2)2 and converged with R1 ¼ 0.0348 (Io >
2
1
[12] 3: H NMR (299.9 MHz, CD2Cl2, 20C, TMS): d ¼ 7.78 7.00 (m,
2s(Io)), wR2 ¼ 0.0825 (all data), GOF ¼ 1.012 and shift/error <
0.001. The asymmetric unit cell contains three crystallographi-
cally independent Pt cations. Two of them (Pt2þ and Pt3þ) are
located around a center of inversion and therefore show a
disorder (in each of two positions, 50:50) which could be clearly
resolved. The two anions and the CH2Cl2 solvent molecule are
well-ordered. Neutral-atom scattering factors for all atoms and
anomalous dispersion corrections for the nonhydrogen atoms
were taken from International Tables for Crystallography.
Crystallographic data (excluding structure factors) for the
structure reported in this paper have been deposited with the
Cambridge Crystallographic Data Centre. CCDC-191944 (4¥0.25
CH2Cl2) contains the supplementary crystallographic data for
this paper. These data can be obtained free of charge via
www.ccdc.cam.ac.uk/conts/retrieving.html (or from the Cam-
bridge Crystallographic Data Centre, 12, Union Road, Cam-
bridge CB21EZ, UK;fax: ( þ 44)1223-336-033;or deposit
@ccdc.cam.ac.uk);b) Data Collection Software for Nonius
kappa-CCD devices, Delft (The Netherlands), 1997;c) Z.
Otwinowski, W. Minor, Methods Enzymol. 1997, 276, 307ff;
d) A. Altomare, G. Cascarano, C. Giacovazzo, A. Guagliardi,
M. C. Burla, G. Polidori, M. Camalli, SIR92, J.Appl.Crystallogr.
1994, 27, 435;e) International Tables for Crystallography, Vol. C,
Tables 6.1.1.4, 4.2.6.8, and 4.2.4.2 (Ed.: A. J. C. Wilson), Kluwer
Academic Publishers, Dordrecht (The Netherlands), 1992;
f) A. L. Spek, PLATON, A Multipurpose Crystallographic Tool,
Utrecht University, Utrecht, 2000;g) G. M. Sheldrick,
SHELXL-97, Universit‰t Gˆttingen, Gˆttingen (Germany),
1998.
38H;aromatic protons), 3.91 (d, J(P,H) ¼ 4.6 Hz, 2J(Pt,H) ¼
109 Hz, 2H;PtCH 2), 2.35 (s, J(Pt,H) ¼ 30.3 Hz, 6H;agostic
CH3), 1.96 ppm (s, 3H;CH 3); 13C NMR (75.4 MHz, CD2Cl2,
20C, TMS): d ¼ 162.2 (q, 1J(C,B) ¼ 50 Hz; ipso aromatic car-
bons), 144.5 143.7 (ipso aromatic carbons), 135.2 125.8 (aro-
matic carbons), 125.0 (q, 1J(C,F) ¼ 272 Hz;CF 3), 117.9 (aromatic
1
3
carbons), 22.7 (s, J(C,Pt) ¼ 840 Hz;PtCH ), 21.6 (d, J(C,P) ¼
2
3.0 Hz;CH 3), 17.6 ppm (s, J(C,Pt) ¼ 94 Hz;agostic CH 3);
31P{1H} NMR (122.4 MHz, CD2Cl2, 20 C, H3PO4): d ¼ 51.3 (d,
2J(P,P) ¼ 351 Hz, 1J(Pt,P) ¼ 2866 Hz), 39.5 ppm (d, 2J(P,P) ¼
351 Hz, 1J(Pt,P) ¼ 2751 Hz);elemental analysis (%) calcd for
C72H49BF24P2Pt: C 52.80, H 3.02;found: C 52.84, H 3.08. 4:
1H NMR (299.9 MHz, CD2Cl2, 20C, TMS): d ¼ 7.68 7.09 (m,
18H;aromatic protons), 4.22 (d, J(P,H) ¼ 4.6 Hz, 2J(Pt,H) ¼
107 Hz, 2H;PtCH 2), 2.70 (s, J(Pt,H) ¼ 64.0 Hz, 3H;agostic
CH3), 2.54 (s, 3H;CH ), 2.50 (s, 3H;CH ), 2.38 1.12 ppm (m,
3
3
44H;Cy); 13C NMR (75.4 MHz, CD2Cl2, 20 C, TMS): d ¼ 162.1
(q, 1J(C,B) ¼ 50 Hz; ipso aromatic carbons), 143.7 141.5 (ipso
aromatic carbons), 135.1 125.3 (aromatic carbons), 124.9 (q,
1J(C,F) ¼ 272 Hz;CF 3), 124.1 and 117.8 (aromatic carbons), 38.7
1
1
(d, J(C,P) ¼ 26.5 Hz;PCH of Cy), 38.0 (d, J(C,P) ¼ 27.5 Hz;
PCH of Cy), 31.9 (d, 2J(C,P) ¼ 104.0 Hz;CH of Cy), 30.9 (d,
2
2J(C,P) ¼ 63.5 Hz, 3J(C,Pt) ¼ 12.0 Hz;CH of Cy), 27.4 26.8 (s,
2
CH2 of Cy), 26.1 (s;CH of Cy), 23.4 and 22.1 (s;CH 3), 17.8 (d,
2J(C,P) ¼ 3.0 Hz, 1J(C,Pt) ¼ 806 Hz;PtCH 2), 13.6 ppm (d,
J(C,P) ¼ 7.7 Hz, J(C,Pt) ¼ 191 Hz;agostic CH 3); 31P{1H} NMR
(122.4MHz, CD2Cl2, 20C, H3PO4): d ¼ 73.3 (d, 2J(P,P) ¼ 316 Hz,
1J(Pt,P) ¼ 2776 Hz), 54.9 ppm (d, 2J(P,P) ¼ 316 Hz, 1J(Pt,P) ¼
2677 Hz);elemental analysis (%) calcd for C 72H73BF24P2Pt: C
52.03, H 4.43;found: C 52.65, H 4.47.
[16] W. T. Klooster, L. Brammer, C. J. Schaverien, P. H. M. Budze-
laar, J.Am.Chem.Soc. 1999, 121, 1381.
[13] B. C. Ankianiec, V. Christou, D. T. Hardy, S. K. Thomson, G. B.
Young, J.Am.Chem.Soc. 1994, 116, 9963.
[14] R. H. Crabtree, E. M. Holt, M. Lavin, S. M. Morehouse, Inorg.
Chem. 1985, 24, 1986.
[17] a) A. C. Albÿniz, G. Schulte, R. H. Crabtree, Organometallics
1992, 11, 242;b) A. J. Toner, S. Gr¸ndemann, E. Clot, H.-H.
Limbach, B. Donnadieu, S. Sabo-Etienne, B. Chaudret, J.Am.
Chem.Soc. 2000, 122, 6777;c) R. H. Morris in Recent Advances
in Hydride Chemistry (Eds.: M. Peruzzini, R. Poli), Elsevier,
Amsterdam 2001, p. 1.
[15] a) Crystal
structure
analysis
of
4¥0.25CH2Cl2:
4(C72H73BF24P2Pt)¥CH2Cl2, Mr ¼ 6733.46, triclinic, space group
ꢀ
P1, a ¼ 13.8101(1), b ¼ 19.2354(2), c ¼ 29.6683(3) ä, a ¼
[18] Notable high 1J(H,Pt) values have been also reported with
nitrogen ligands: G. Minghetti, M. A. Cinellu, S. Stoccoro, G.
Chelucci, A. Zucca, Inorg.Chem. 1990, 29, 5138.
101.466(1), b ¼ 93.333(1), g ¼ 109.049(1)8, V¼ 7236.26(13) ä3,
Z ¼ 1, 1calcd ¼ 1.545 gcmÀ3, F000 ¼ 3378, m ¼ 2.105 mmÀ1. A suit-
able single crystal for the X-ray diffraction study was obtained
from a CH2Cl2/toluene solution at 48C. The selected crystal was
coated with perfluorinated ether, fixed in a capillary, and
transferred to the diffractometer and the cold nitrogen flow
(Oxford Cryosystems). Preliminary examinations and data
[19] D. G. Gusev, J. U. Notheis, J. R. Rambo, B. E. Hauger, O.
Eisenstein, K. G. Caulton, J.Am.Chem.Soc.
1994, 116, 7409.
[20] M. E. van der Boom, J. Ott, D. Milstein, Organometallics 1998,
17, 4263.
108
¹ 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1433-7851/03/4201-0108 $ 20.00+.50/0
Angew. Chem. Int. Ed. 2003, 42, No. 1