Crystal structure of [Zr(dmpe){CH2Si(CH3)3}4](dmpe = PMe2CH2CH2PMe2). Evidence in support of the postulation for the presence of an agostic hydrogen

Abstract

[Zr{CH2Si(CH3)3}4] reacts with PMe2CH2CH2PMe2(dmpe) to form the title compound, [Zr(dmpe){CH2Si(CH3)3}4]. The complex belongs to the triclinic space group P, with cell constants a= 9.999(6), b= 10.638(7), c= 19.927(6)Å, α= 76.54(4), β= 83.05(4), γ= 62.29(4)°, and Z= 2. Least-squares refinement based on 3 421 observed reflections led to a final R of 0.063. There is direct evidence for a significant interaction of an α-hydrogen with the zirconium atom. The four Zr–C lengths fall in the pattern: very short [2.215(9)Å], short [2.27(1)Å], and normal [2.312(8), 2.322(8)Å]. The Zr–C–Si angles also reflect the trend in bond lengths with values of 141.5(6), 137.8(6), 130.0(4), and 128.6(4)°, respectively. The hydrogen atoms were located, and the closest Zr ⋯ H approach, 2.48 Å, is for a hydrogen atom bonded to the carbon nearest the zirconium.