Double addition of the Si-H bonds of Pt(SiHPh2)2(PMe3)2 to nitriles to afford 3-aza-2,4-disilaplatinacyclobutanes

Article abstract of DOI:10.1021/om010059u

The reactions of PhCN and MeCN with Pt(SiHPh₂)₂(PMe₃)₂ led to double addition of Si-H bonds to the C≡N triple bond of the nitriles to produce the 3-aza-2,4-disilaplatinacyclobutanes, Pt(SiPh₂-NR-SiPh<

Full text of DOI:10.1021/om010059u

2118
Organometallics 2001, 20, 2118-2120
Dou ble Ad d ition of th e Si-H Bon d s of
P t(SiHP h 2)2(P Me3)2 to Nitr iles to Affor d
3-Aza -2,4-d isila p la tin a cyclobu ta n es
Makoto Tanabe and Kohtaro Osakada*
Chemical Resources Laboratory, Tokyo Institute of Technology,
4259 Nagatsuta, Midori-ku, Yokohama 226-8503, J apan
Received J anuary 25, 2001
Summary: The reactions of PhCN and MeCN with Pt-
(SiHPh2)2(PMe3)2 led to double addition of Si-H bonds
to the CtN triple bond of the nitriles to produce the
3-aza-2,4-disilaplatinacyclobutanes, Pt(SiPh2-NR-SiPh2)-
(PMe3)2 (R ) CH2Ph, Et). Structure determined by X-ray
crystallography of the complexes revealed mononuclear
structures with planar four-membered rings composed
of a disilazanediyl ligand and a platinum center.
In tr od u ction
Transition metal complex-promoted catalytic or
stoichiometric addition of the Si-H bond to the CtN
bond has been reported to a lesser extent than the
hydrosilylation of CdC, CtC, and CdO bonds. The Rh
complex-catalyzed reaction of organosilanes with acrylo-
nitrile results in the addition of an Si-H bond to the
CdC double bond to yield â-silylpropionitriles,1 which
suggests hydrosilylation of the CtN bond is more
difficult compared to the CdC bond. Hydrosilylation of
nitriles was achieved using Co2(CO)8 as a catalyst,
producing disilazanes via the addition of two Si-H
bonds to the CtN bond.2,3 A related stoichiometric Si-N
bond formation was reported in the reaction of 2,5-
F igu r e 1. (a) ORTEP drawing of 1 at 50% ellipsoidal level.
Selected bond distances (Å) and angles (deg): Pt-P1
2.338(3), Pt-P2 2.328(3), Pt-Si1 2.366(4), Pt-Si2 2.377-
(3), Si1-N 1.734(8), Si2-N 1.726(8), N-C1 1.47(1), C1-
C2 1.49(1), Si1‚‚‚Si2 2.630(4), P1-Pt-P2 102.8(1), P1-Pt-
Si1 93.3(1), P1-Pt-Si2 160.3(1), P2-Pt-Si1 163.2(1), P2-
Pt-Si2 96.3(1), Si1-Pt-Si2 67.3(1), Pt-Si1-N 96.9(3),
Pt-Si2-N 96.7(3), Si1-N-Si2 98.9(4), Si1-N-C1
129.7(6), Si2-N-C1 128.9(7), N-C1-C2 113.9(9). (b)
ORTEP drawing 2‚toluene at 50% ellipsoidal level. Sol-
vated toluene was omitted for simplicity. Selected bond
distances (Å) and angles (deg): Pt-P1 2.323(3), Pt-P2
2.318(3), Pt-Si1 2.365(3), Pt-Si2 2.350(3), Si1-N
1.730(8), Si2-N 1.732(7), N-C1 1.44(1), C1-C2 1.38(2),
Si1‚‚‚Si2 2.627(4), P1-Pt-P2 98.9(1), P1-Pt-Si1 95.6(1),
P1-Pt-Si2 162.4(1), P2-Pt-Si1 165.5(1), P2-Pt-Si2
97.8(1), Si1-Pt-Si2 67.7(1), Pt-Si1-N 96.2(3), Pt-Si2-N
96.7(3), Si1-N-Si2 98.7(4), Si1-N-C1 130.3(7), Si2-N-
C1 129.4(7), N-C1-C2 120(1).
disilaferracyclopentane, (CO)4FeSiPh2-CRdCR-SiPh2,
with a nitrile to afford the corresponding five-membered
cyclic disilazane.4 We report here a new reaction, the
stoichiometric addition of the Si-H bonds of SiHPh2
ligands bonded to Pt to the CtN bond to afford 3-aza-
2,4-disilaplatinacyclobutanes.
nacyclobutanes, (Me3P)2Pt(SiPh2-N(CH2R)-SiPh2) (1: R
) Ph, 2: R ) Me), in 62% and 64% yield, respectively
(eq 1). The reaction mixture does not contain other
possible products such as those from the insertion of
the CtN bond into the Pt-Si bond or those from bis-
silylation of the nitriles.3
Resu lts a n d Discu ssion
5
Heating Pt(SiHPh2)2(PMe3)2 in benzonitrile and in
acetonitrile at 70-80 °C afforded 3-aza-2,4-disilaplati-
(1) (a) Nozakura, K.; Konotsune, S. Bull. Chem. Soc. J pn. 1956, 29,
322. (b) Belyakova, Z. V.; Golubstov, S. A.; Yakusheva, T. M. Zh.
Obshch. Khim. 1962, 32, 1997; Chem. Abstr. 1963, 58, 4591. (c) Chalk,
A. J . J . Organomet. Chem. 1970, 21, 207. (d) Ojima, I.; Kumagai, M.
J . Organomet. Chem. 1976, 111, 43.
(2) Murai, T.; Sakane, T.; Kato, S. Tetrahedron Lett. 1985, 26, 5145.
(3) Pt complex promoted 1,2-bissilylation of nitriles by 1,2-bis-
(dimethylsilyl)benzene was reported to give the corresponding hetero-
cyclic products. Reddy, N. P.; Uchimaru, Y.; Lautenschlager, H.-J .;
Tanaka, M. Chem. Lett. 1992, 45.
(4) Corriu, R. J . P.; Moreau, J . J . E.; Pataud-Sat, M. Organometallics
1985, 4, 623.
(5) The complex exists as an equilibrium mixture of the cis and trans
isomers in solution. See: Kim, Y.-J .; Park, J .-I.; Lee, S.-C.; Osakada,
K.; Tanabe, M.; Choi, J .-C.; Koizumi, T.; Yamamoto, T. Organometallics
1999, 18, 1349.
Results of an X-ray crystallographic study of 1 and 2
indicated a mononuclear structure with chelating di-
silazanediyl ligands as shown in Figure 1 rather than
alternative di- or multinuclear structures with bridging
ligands. An analogous 3-aza-2,4-disilaplatinacyclobu-
10.1021/om010059u CCC: $20.00 © 2001 American Chemical Society
Publication on Web 04/21/2001

Notes
Organometallics, Vol. 20, No. 10, 2001 2119
Ta ble 1. Cr ysta llogr a p h ic Da ta a n d Deta ils of
tane without N-alkyl substituents, Pt(SiMe2-NH-SiMe2)-
(dppe) (dppe ) 1,2-bis(diphenylphosphino)ethane) was
prepared by the reaction of Pt(η2-SiMe2SiMe2)(dppe)
with NH3,6 but its precise bond parameters were not
determined. The bond parameters of the platinacyclobu-
tane part of the complexes 1 and 2 are similar to each
Refin em en t of 1 a n d 2‚Tolu en e
1
2‚toluene
chemical formula
fomula weight
crystal system
space group
a, Å
C
37H45NP2Si2Pt
C39H51NP2Si2Pt
847.05
monoclinic
P21/c (No. 14)
9.965(4)
816.98
triclinic
P1h (No. 2)
10.932(8)
19.284(7)
9.583(5)
102.56(4)
112.04(4)
79.73(5)
1817(2)
2
other and also to those of Pt(SiMe2-O-SiMe2)(dppe).6 The
four-membered rings composed of Pt, Si, and N (or O)
atoms are essentially planar; the sum of the four bond
angles of the chelating ligand and the metal center are
approximately 360°. Complexes 1 and 2 contain close
SiSi contacts (2.630(4) and 2.627(4) Å) and acute Si-
Pt-Si bond angles (67.3(1)° and 67.7(1)°). These bond
distances and angles are somewhat larger than those
b, Å
c, Å
16.034(3)
25.097(3)
R, deg
â, deg
98.46(2)
γ, deg
V, Å3
3966(2)
4
3.691
1712
Z
µ, mm-1
F(000)
4.025
820
1.493
D
calcd, g cm-3
1.418
in Pt(SiMe2-O-SiMe2)(dppe) (2.549(2) Å and 65.0(1)°).6,7
The NMR spectra of 1 and 2 also support structures
with a disilazanediyl ligand bonded to the square-planar
cryst size,
0.61 × 0.57 × 0.34
0.68 × 0.34 × 0.20
mm × mm × mm
2θ range, deg
unique reflections
used reflections
(I > 3.0σ(I))
no. of variables
R
5.0-55.0
8347
6368
5.0-55.0
9428
4235
1
Pt center in a chelating manner. The H and 13C{1H}
NMR signals of the PMe3 ligands indicate the presence
of two equivalent phosphine ligands at the cis positions.
388
0.050
0.057
371
0.048
0.046
The 29Si{1H} NMR signal shows splitting due to two 31
P
Rw
nuclei in the trans and cis positions (2J SiP ) 154, 18 Hz
for 1 and 154, 17 Hz for 2). The peak positions (δ -10.6
(1) and -13.5 (2)) are similar to those reported for the
NH containing 3-aza-2,4-disilaplatinacyclobutane
an orange solid that was collected by filtration, washed
repeatedly with hexane, and dried in vacuo to give 1 as a pale
yellow solid (336 mg, 62%). Recrystallization from toluene-
hexane afforded pale yellow crystals suitable for X-ray crystal-
lography. Anal. Calcd for C37H45NP2PtSi2: C, 54.40; H, 5.55;
N, 1.71. Found: C, 54.63; H, 5.81; N, 1.72. 1H NMR (400 MHz,
(δ -12.1 for Pt(SiMe2-NH-SiMe2)(dppe)).6 The CH2-N
carbon in the 13C{1H} NMR spectra of the complexes
exhibits symmetrical triplet signals due to two equiva-
lent phosphorus nuclei (4J CP ) 6 Hz).
In summary, this study provides a convenient method
for the preparation of 2,4-disila-3-azaplatinacyclobu-
tanes with N-substituents. The addition of the Si-H
bond of the silyl ligand to the CtN bond occurs at
elevated temperature to afford the products selectively.
2
3
CD2Cl2): δ 1.22 (m, 18H, PMe3, J HP ) 7 Hz, J HPt ) 21 Hz),
3.72 (s, 2H, CH2, 4J HPt ) 8 Hz), 6.60 (d, 2H, CH2C6H5-o, J HH
)
7 Hz), 6.73 (t, 2H, CH2C6H5-m, J HH ) 7 Hz), 6.83 (t, 1H,
CH2C6H5-p, J HH ) 7 Hz), 7.27 (m, 12H, SiC6H5-m and -p), 7.69
(m, 8H, SiC6H5-o). 13C{1H} NMR (75 MHz, CD2Cl2): δ 19.1
2
(apparent triplet, PMe3, J CP ) 14 Hz, J CPt ) 28 Hz), 51.9 (t,
4
3
CH2, J CP ) 6 Hz, J CPt ) 138 Hz), 124.8 (CH2C6H5-p), 126.6
(SiC6H5-m), 126.8 (CH2C6H5-m), 127.2 (CH2C6H5-o), 128.5
3
(SiC6H5-p), 136.2 (SiC6H5-o, J CPt ) 20 Hz), 142.6 (CH2C6H5-
ipso), 143.9 (t, SiC6H5-ipso, J CP ) 5 Hz, J CPt ) 38.9 Hz). 31P-
{1H} NMR (162 MHz, CD2Cl2): δ -15.4 (2J PSi ) 129 Hz, J PPt
) 1661 Hz). 29Si{1H} NMR (79 MHz, CD2Cl2, -70 °C): δ -10.6
3
2
Exp er im en ta l Section
Gen er a l Meth od s. All manipulations of the Pt complexes
were carried out using standard Schlenk techniques under
argon or nitrogen atmosphere. Pt(SiHPh2)2(PMe3)2 was pre-
pared according to the literature method.5 Benzonitrile, dis-
tilled from CaH2, and dry acetonitrile purchased from Kanto
Chemical Co., Inc. were stored under nitrogen. NMR spectra
(1H, 13C{1H}, 29Si{1H}, 31P{1H}) were recorded on J EOL EX-
400 or Varian Mercury 300 spectrometers. 31P{1H} and 29Si-
{1H} NMR peak positions are referenced to external 85%
H3PO4 and external SiMe4, respectively. Elemental analyses
were carried out with a Yanaco MT-5 CHN autocorder.
(2J SiP cis ) 18 Hz, J SiP trans ) 154 Hz, J SiPt ) 1050 Hz).
2
Complex 2 was obtained similarly as a yellow solid (343 mg,
64%) and recrystallized from toluene-hexane. Anal. Calcd for
C
32H43NP2PtSi2: C, 50.91; H, 5.74; N, 1.86. Found: C, 51.25;
H, 5.90; N, 2.16. 1H NMR (400 MHz, C6D6): δ 0.87 (d, 18H,
2
3
3
PMe3, J HP ) 7 Hz, J HPt ) 23 Hz), 0.95 (t, 3H, CH3, J HH ) 7
3
4
Hz), 3.07 (q, 2H, CH2, J HH ) 7 Hz, J HPt ) 8 Hz), 7.24 (t, 8H,
C6H5-p, J HH ) 7 Hz) 7.34 (t, 8H, C6H5-m, J HH ) 7 Hz), 8.14 (d,
8H, C6H5-o, J HH ) 7 Hz). 13C{1H} NMR (100 MHz, CDCl3): δ
2
18.1 (CH3), 19.8 (apparent triplet, PMe3, J CP ) 13 Hz, J CPt
)
28 Hz), 42.0 (t, CH2, 4J CP ) 6 Hz, 3J CPt ) 132 Hz), 126.6 (C6H5-
m), 127.4 (C6H5-p), 136.5 (C6H5-o, 3J CPt ) 20 Hz), 144.8 (t, C6H5-
P r ep a r a tion of P t(SiP h 2-NCH2P h -SiP h 2)(P Me3)2 (1)
3
2
ipso, J CP ) 6 Hz, J CPt ) 39 Hz). 31P{1H} NMR (162 MHz,
a n d P t(SiP h 2-NEt-SiP h 2)(P Me3)2 (2). A solution of Pt-
(SiHPh2)2(PMe3)2 (478 mg, 0.67 mmol) in benzonitrile (15 mL)
was heated for 12 h at 70-80 °C. The color of the solution
turned from yellow to orange during the course of the reaction.
The solvent was removed at reduced pressure. Addition of
hexane to the resulting red residue caused the separation of
C6D6): δ -16.2 (2J PSi ) 125 Hz, J PPt ) 1650 Hz). 29Si{1H} NMR
(79 MHz, CD2Cl2, -70 °C): δ -13.5 (2J SiP cis ) 17 Hz, J SiP
2
trans ) 154 Hz, J SiPt ) 1048 Hz).
Cr ysta l Str u ctu r e Deter m in a tion . Crystals of 1 and 2‚
toluene were mounted in glass capillary tubes under Ar.
Intensities were collected for Lorentz and polarization effects
on a Rigaku AFC-5R automated four-cycle diffractometer by
using MoKR radiation (λ ) 0.710 69 Å) and ω - 2θ scan
method, and an empirical absorption correction (Ψ scan) was
applied. Calculations were carried out by using a program
package teXsan for Windows. Atomic scattering factors were
obtained from the literature.8 A full-matrix least-squares
refinement was used for non-hydrogen atoms with anisotoropic
thermal parameters. Carbon atoms of solvated toluene of 2‚
(6) Pham, E. K.; West, R. Organometallics 1990, 9, 1517. See also:
Osakada, K.; Tanabe, M.; Tanase, T. Angew. Chem., Int. Ed. 2000,
39, 4053.
(7) Other examples of SiSi contact: Zarate, E. A.; Tessier-Youngs,
C. A.; Youngs, W. J . J . Am. Chem. Soc. 1988, 110, 4068; Anderson, A.
B.; Shiller, P.; Zarate, E. A.; Tessier-Youngs, C. A.; Tessier-Youngs,
W. J . Organometallics 1989, 8, 2320. See also: Alemany, P.; Alvarez,
S. Inorg. Chem. 1992, 31, 4266. Aullo´n, G.; Alemany, P.; Alvarez, S.
J . Organomet. Chem. 1994, 478, 75.

2120 Organometallics, Vol. 20, No. 10, 2001
Additions and Corrections
toluene were refined isotropically. Hydrogen atoms were
located by assuming the ideal geometry and included in the
structure calculation without further refinement of the pa-
rameters. Crystal data and details of refinement of 1 and 2
are summarized in Table 1.
Ack n ow led gm en t. This work was supported by a
Grant-in-Aid for Scientific Research from the Ministry
of Education, Science, Sports, and Culture, J apan.
Su p p or tin g In for m a tion Ava ila ble: Crystallographic
data of 1 and 2‚toluene. This material is available free of
charge via the Internet at http://pubs.acs.org.
(8) International Tables for X-ray Crystallography; Kynoch: Bir-
mingham, England, 1974; Vol. 4.
OM010059U
Additions and Corrections
2001, Volume 20
D. Am a r a sin gh e,
Ka n d e
K.
Sa n joy
K.
Ch ow d h u r y, Ma r y J a n e Heeg, a n d J oh n
Mon tgom er y*: Structure of an η1 Nickel O-Enolate:
Mechanistic Implications in Catalytic Enyne Cycliza-
tions.
Page 370. A relevant reference (Kaschube, W.; Schro¨-
der, W.; Po¨rschke, K. R.; Angermund, K.; Kru¨ger, C. J .
Organomet. Chem. 1990, 389, 399) that describes the
formation of a nickel metallacyclopentene by the inter-
molecular coupling of an alkene and an alkyne was
omitted. A second relevant reference (Bu¨ch, H. M.;
Binger, P.; Benn, R.; Rufinska, A. Organometallics 1987,
6, 1130) that describes the formation of a nickel met-
allacyclopentane which incorporates methyl acrylate
was also omitted.
OM010218+
10.1021/om010218+
Published on Web 04/07/2001