Contrasting Nonclassical Silicon−Hydrogen Interactions in Niobium and Tantalum Half-Sandwich Complexes: Si−H···M Agostic versus M−H···Si−Cl Interligand Hypervalent Interactions

Reactions of Hydrosilanes with Transition Metal Complexes and Characterization of the Products

“…Data are given for the major isomer. 146 2 ] occurs with the following silanes: HClSi i Pr 2 , ClSiMe 3 , Cl 2 SiMe 2 or HSiMe 2 Ph under conditions comparable to those that gave 3-17. 147a 3-18 is believed to be an isomer of 3-17 with the phosphine trans to Si-H and the Cl atom cis to Si-H. 147a 120 X-ray structure was only of sufficient quality to establish overall geometry.…”

“…Table 7), and the Si-Cl distance is slightly shorter than that observed in the complexes listed in Table 13. 146 A minor change in the NAr group to 2,6-(Me) 2 C 6 H 3 in the Nb precursor produced the complex 3-19, an isomer of 3-17a in which the phosphine and the chloride exchanged places. 147a However, changing the silane from HSiMe 2 Cl to HSiPh 2 Cl resulted in formation of the classical silylhydrido complex Cp(ArN)(Me 3 P)-Nb(H)SiPh 2 Cl, 3-21, 149 as was the case for the SiPhMeCl, SiMeCl 2 , SiCl 3 complexes, although the DFT calculations for both 3-21 and the corresponding SiCl 3 complex ( Table 3, footnote 33) suggested IHI character in contrast to the X-ray data.…”

“…Data are given for the major isomer 3-17. 146 2 ] occurred with the following silanes: HClSi i Pr 2 , ClSiMe 3 , Cl 2 SiMe 2 , or HSiMe 2 Ph under conditions comparable to those that gave 3-17. 147a 3-17 and 3-18 are isomers that differ in position of the Me 3 P and Cl ligands.…”