Theoretical study of tungsten η3-Silaallyl/η3-Vinylsilyl and vinyl silylene complexes:: Interesting bonding nature and relative stability

被引:22
作者
Ray, Mausumi
Nakao, Yoshihide
Sato, Hirofumi
Sakaki, Shigeyoshi [1 ]
机构
[1] Kyoto Univ, Grad Sch Engn, Div Mol Engn, Nishikyo Ku, Kyoto 6158510, Japan
[2] Fukui Inst Fundamental Chem, Kyoto 6068103, Japan
关键词
D O I
10.1021/om7005563
中图分类号
O61 [无机化学];
学科分类号
070301 ; 081704 ;
摘要
The geometries and bonding nature of interesting new tungsten eta(3)-silaallyl/eta(3)-vinylsilyl complex Cp(CO)(2)W(eta(3)-H2SiCHCH2) (1) and tungsten vinyl silylene complex Cp(CO)(2)W(CHCH2)(SiH2) (2) and the conversion reaction of 1 to 2 were theoretically investigated with the density functional theory (DFT) and CCSD(T) methods, where 1 was adopted as a model of Cp*(CO)(2)W(eta(3)-Me2SiCHCMe2). The nonbonding pi orbital (phi(n pi)) of the eta(3)-H2SiCHCH2 group is similar to that of the eta(3)-allyl group except that the Si p orbital more contributes to phi(n pi) than the C p orbital. On the other hand, the pi orbital (phi(pi)) of the eta(3)-H2SiCHCH2 group is considerably different from that of the eta(3)-allyl group; the pi-conjugation between the Si and C atoms is very weak, unlike that of the eta(3)-allyl group in which pi-conjugation is considerably strong. Thus, 1 can be understood to be a species between tungsten eta(3)-vinylsilyl and tungsten eta(3)-silaallyl complexes. From the geometry and frontier orbitals, 2 can be understood to be a tungsten vinyl silylene complex in which charge transfer interaction between the silylene and vinyl groups is very weak. Complex 1 is much more stable than 2 by 21.0 (20.9) kcal/mol, but Cp(CO)(2)W(eta(3)-H2SiCCH) (3) is less stable than Cp(CO)(2)W(CCH)(SiH2) (4) by 0.7 (4.9) kcal/mol, where the CCSD(T)- and DFT-calculated values are given without and in parentheses, respectively. This means that the tungsten eta(3)-silaallyl/eta(3)-vinylsilyl complex can be isolated but the tungsten vinyl silylene complex cannot, unlike the tungsten acetylide silylene complex Cp*(CO)(2)W((CCBu)-Bu-t)(SiPh2) which was isolated recently. Complex 1 converts to 2 with a large activation barrier of 34.2 (33.2) kcal/mol, while 3 easily converts to 4 with a moderate activation barrier of 15.8 (15.3) kcal/mol. These differences between 1 and 3 can be interpreted as follows: Though the Si-C bond is weak in 1, the W-(eta(3)-H2SiCHCH2) interaction is considerably strong. Moreover, the W-vinyl and silylene-vinyl interactions are very weak in 2. On the other hand, the Si-C bond is strong but the W-(eta(3)-H2SiCCH) interaction is weak in 3. Moreover, the W-acetylide and silylene-acetylide interactions are very strong in 4. The reasons are discussed in detail.
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页码:4413 / 4423
页数:11
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共 37 条
[1]  
[Anonymous], GAUSSIAN 03 REVISION
[2]   A QUANTUM-THEORY OF MOLECULAR-STRUCTURE AND ITS APPLICATIONS [J].
BADER, RFW .
CHEMICAL REVIEWS, 1991, 91 (05) :893-928
[3]   DENSITY-FUNCTIONAL THERMOCHEMISTRY .3. THE ROLE OF EXACT EXCHANGE [J].
BECKE, AD .
JOURNAL OF CHEMICAL PHYSICS, 1993, 98 (07) :5648-5652
[4]   DENSITY-FUNCTIONAL EXCHANGE-ENERGY APPROXIMATION WITH CORRECT ASYMPTOTIC-BEHAVIOR [J].
BECKE, AD .
PHYSICAL REVIEW A, 1988, 38 (06) :3098-3100
[5]  
Couty M, 1996, J COMPUT CHEM, V17, P1359, DOI 10.1002/(SICI)1096-987X(199608)17:11<1359::AID-JCC9>3.0.CO
[6]  
2-L
[7]  
Dai XS, 1999, CHEM LETT, P717
[8]   SELF-CONSISTENT MOLECULAR-ORBITAL METHODS .9. EXTENDED GAUSSIAN-TYPE BASIS FOR MOLECULAR-ORBITAL STUDIES OF ORGANIC MOLECULES [J].
DITCHFIELD, R ;
HEHRE, WJ ;
POPLE, JA .
JOURNAL OF CHEMICAL PHYSICS, 1971, 54 (02) :724-+
[10]   Silabenzene and disilabenzene complexes of ruthenium [J].
Dysard, JM ;
Tilley, TD ;
Woo, TK .
ORGANOMETALLICS, 2001, 20 (06) :1195-1203