A Comparison of the Reactivity of Ni Atoms Toward CH₄, SiH₄, and SnH₄: A Combined Matrix Isolation and Quantum‐Chemical Study

Nickel atoms are shown to react spontaneously with SiH(4) and SnH(4) to give the insertion products HNiSiH(3) and HNiSnH(3). With CH(4), however, no spontaneous reaction occurs, in agreement with earlier reports; HNiCH(3) can be formed only on photolytic activation of the Ni atom. The reaction products were characterized experimentally by IR spectroscopy, including the effect of isotopic substitution (H/D), and by quantum-chemical calculations. They all have C(s) symmetry with a terminal Ni--H bond and three terminal E--H bonds (E=Si, Sn). Strikingly, the H-Ni-E bond angles are less than 90 degrees, and there is a weak interaction between the H atom bound to Ni and the E atom. The structures are compared with those of other molecules of general formula MSiH(4) that have been characterized recently in our group (M=Ti, Ni, Ga). While TiSiH(4) has three Ti-H-Si bridges, both NiSiH(4) and GaSiH(4) exhibit only terminal Ni--H and E--H bonds, but with the difference that there is no interaction between the H atom bound to Ga and the Si atom.