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Y.-H. Li et al. / Journal of Molecular Structure 1097 (2015) 181–184
short pad of SiO2 to remove a remaining salt. After evaporation,
the residue was subjected to bulb-to-bulb distillation to give
14.5 g (60 %) of 1,2-bis(triisopropoxysilyl) benzene. The product
obtained by bulb-to-bulb distillation was used for the next step
without further purification. IR (neat) 3048, 2974, 1466, 1381,
1371, 1174, 1125, 1038, 886, 750, 704, 538, 505; 1H NMR (CDCl3,
300 MHz) d 1.20 (36H, d, J = 6), 4.34 (6H, septet, J = 6), 7.37 (2H,
dd, J = 3.5, 5.5), 7.95 (2H, dd, J = 3.5, 5.5); 13C NMR (CDCl3,
300 MHz)
(CDCl3, 300 MHz) d-62.94. Calcd. (%) Elemental analysis for
d
25.53, 65.39, 128.30, 136.75, 139.99; 29Si NMR
Scheme 1. The reaction of the parent chelating silane, 1,2-C6H4(SiH3)(SiH3) (1) with
Pt(dcpe)(PEt3)2 (dcpe = Cy2PCH2CH2PCy2) in the ratio of 1:1, leading to a mononu-
clear complex {1,2-C6H4(SiH2)(SiH2)}PtII(dcpe) (2).
C24H46O6Si2: C, 59.22; H, 9.52. Found: C, 59.07; H, 9.57.
To an ether suspension (30 mL) of LiAlH4 (0.97 g, 26 mmol) was
added dropwise a solution of 1,2-bis(triisopropoxysilyl)benzene
(4.6 g, 9.5 mmol) in ether (20 mL) at 0 °C over 40 min. The mixture
was stirred for 5 h at room temperature. GC–MS analysis of the
mixture at this stage showed the presence of partially reduced
products. Then, LiAlH4 (0.3 g) was added and the mixture was stir-
red for another 3 h at room temperature. After removal of ether
under reduced pressure, the remaining mixture was extracted with
pentane (20 mL ⁄ 3), and then filtered through Celite. After evapo-
ration, the residue was distilled to gave 1,2-disilylbenzene 1
(0.76 g, 59%). IR (neat) 3053, 2163, 1126, 933, 903, 755, 734, 651;
1H NMR (CDCl3, 300 MHz) d 4.30 (6H, s), 7.41 (2H, dd, J = 3.5,
5.5), 7.68 (2H, dd, J = 3.5, 5.5); 13C NMR (CDCl3, 300 MHz) d
129.47, 136.52, 137.21; 29Si NMR (CDCl3, 300 MHz) d-61.05.
bearing hydroxy group with low steric hindrance to form a
tetra-alkoxy substituted silyl platinum(II) compound (3)
(Scheme 2). The structures of complexes (2) and (3) were unam-
biguously determined by multinuclear NMR spectroscopic studies
and single crystal X-ray analysis.
Experimental
Materials and equipment
1H, 29Si and 31P NMR spectra were recorded on Jeol LA500 (for
solution NMR). Chemical shifts are given in ppm using external ref-
erences (for solution NMR spectra, tetramethylsilane (0 ppm) for
1H and 29Si and 85% H3PO4 (0 ppm) for 31P), and coupling constants
are reported in hertz. C, H and N analyses were taken on a Perkin-
Elmer 240C elemental analyzer. All reagents and solvents were of
reagent-grade quality obtained from commercial suppliers. All sol-
vents were dried and distilled from Na/benzophenone ketyl. The
solvents were stored over molecular sieves (4 Å). All manipulations
of air-sensitive materials were carried out under a nitrogen atmo-
sphere using standard Schlenk tube techniques. 1,2-bis
(dicyclohexylphosphino) ethane (Aldrich) were purchased and
used as received, Pt(PEt3)4 and hydrosilane 1,2-C6H4(SiH3)(SiH3)
were prepared according to the relevant literature method [4b,6].
Preparation of {1,2-C6H4(SiH2)(SiH2)}PtII(dcpe) complex (2)
A mixture of Pt(PEt3)4 (216 mg, 0.32 mmol) and dcpe (135 mg,
0.32 mmol) in toluene (4 mL) was stirred at room temperature
for 40 min to give Pt(PEt3)2(dcpe). After removal of volatiles under
vacuum, the residual was dissolved in toluene (4 mL). To this solu-
tion was added hydrosilane (1, 44 mg, 0.32 mmol) at 0 °C, and the
mixture was stirred at 0 °C for 12 h and then at room temperature
for 24 h. Removal of volatiles under vacuum afforded a light yellow
residue, which was washed with hexane (2 mL ⁄ 3) and dried
under vacuum to give the product 2 as a colorless solid, 181 mg
(75%). 31P{1H} NMR (THF-d8, 202.0 MHz): for 2, d 78.13 (s,
1JPt-P = 1653 Hz). 1H NMR (THF-d8, 499.1 MHz): for 2, d 0.51 (dd,
6H, Si–CH3), 1.16–1.91 (m, 44H, –Cy2P–), 2.26–2.36 (m, 4H, –
PCH2CH2P–), 5.69 (dd, 4H, SiH2), 7.04 (dd, 2H, aromatic-H), 7.64
(dd, 2H, aromatic-H). 29Si{1H} NMR (THF-d8, 99.1 MHz, DEPT): for
Synthesis
2
2
1
2, d-14.09 (dd, JP-Si = 149 Hz, JP-Si = 13 Hz, JPt-Si = 1097 Hz, SiH2).
Calcd. (%) Elemental analysis for C32H56P2PtSi2: C, 50.97; H, 7.49.
Found: C, 51.36; H, 7.78.
Preparation of 1,2-disilylbenzene complex (1)
To
a
solution of phenyltris(N,N,N0-Trimethyl ethylenedi-
amino)silane (20.4 g, 0.05 mol) in hexane (100 mL) was added a
pentane solution of tBuLi (1.7 M, 84 mL, 0.114 mol) over 30 min
at 0 °C under nitrogen. After stirring at rt for 3 h, the solution
was added by using polyethylene tube to a solution of SiC14
(61 g, 0.36 mol) in hexane (50 mL) at ꢁ75 °C over 1 h. After addi-
tion was completed, the mixture was allowed to warm to rt and
stirred for 3 h. The solvents and excess of SiC14 were removed
under reduced pressure at rt. After the addition of hexane
(50 mL) to the residue, iPrOH (90 mL) was added dropwise at
0 °C. The mixture was stirred at rt for 12 h. Volatiles were removed
under vacuum, hexane (140 mL) was added, and the mixture was
filtered through Celite. The filtrate was further filtered through a
Preparation of {1,2-C6H4[Si(OCH3)2Si(OCH3)2]}PtII(dcpe) complex (3)
In a Schlenk tube equipped with a magnetic stirrer bar,
{1,2-C6H4(SiH2) (SiH2)}PtII(dcpe) (377 mg, 0.5 mmol) and dry
methanol (6 mL) were placed. The mixture was stirred at room
temperature for 3 h under nitrogen, and then stirred at 60° for
about 10 h. Removal of volatiles under vacuum afforded a light yel-
low residue, which was washed with hexane (2 mL ⁄ 3) and dried
under vacuum to give the product 3 as a colorless solid, 284 mg
(65%). 31P{1H} NMR (C6D6, 202.0 MHz): for 3,
d 75.54 (s,
1JPt-P = 1411 Hz). 1H NMR (C6D6, 499.1 MHz): for 3, d 0.51 (dd,
6H, Si–CH3), 1.18–1.81 (m, 44H, –Cy2P–), 2.31–2.41 (m, 4H, –
PCH2CH2P–), 3.66 (s, 12H, OCH3), 7.47 (dd, 2H, aromatic-H), 8.18
(dd, 2H, aromatic-H). 29Si{1H} NMR (C6D6, 99.1 MHz, INEPT): for
2
2
3, d 27.58 (dd, JP-Si = 139 Hz, JP-Si = 10 Hz, SiMe2). Calcd. (%)
Elemental analysis for C36H64O2P2PtSi2: C, 51.35; H, 7.66. Found:
C, 51.76; H, 7.97.
X-ray crystallography
The diffraction data were collected at 293 K on a Bruker Smart
Scheme 2. The reaction of complex 2 with methanol affords a novel tetra-methoxy
substituted silyl platinum(II) compound 3.
APEX CCD diffractometer with Mo K
a radiation (k = 0.71073 Å),