Rearrangement of a Ge(ii) aryloxide to yield a new Ge(ii) oxo-cluster [Ge6(μ3-O)4(μ2-OC6H2-2,4,6-Cy3)4](NH3)0.5: main group aryloxides of Ge(ii), Sn(ii), and Pb(ii) [M(OC6H2-2,4,6-Cy3)2]2 (Cy = cyclohexyl)

Abstract

The new Ge(II) cluster [Ge₆(μ₃-O)₄(μ₂-OC₆H₂-2,4,6-Cy₃)₄](NH₃)_0.5 (1) and three divalent Group 14 aryloxide derivatives [Ge(OC₆H₂-2,4,6-Cy₃)₂]₂ (2), [Sn(OC₆H₂-2,4,6-Cy₃)₂]₂ (3), and [Pb(OC₆H₂-2,4,6-Cy₃)₂]₂ (4) of the new tricyclohexylphenyloxo ligand, [(–OC₆H₂-2,4,6-Cy₃)₂]₂ (Cy = cyclohexyl), were synthesized and characterized. Complexes 1–4 were obtained by reaction of the metal bissilylamides M(N(SiMe₃)₂)₂ (M = Ge, Sn, Pb) with 2,4,6-tricyclohexylphenol in hexane at room temperature. If the freshly generated reaction mixture for the synthesis of 2 is stirred in solution for 12 h at room temperature, the cluster [Ge₆(μ₃-O)₄(μ₂-OC₆H₂-2,4,6-Cy₃)₄](NH₃)_0.5 (1), which features a rare Ge₆O₈ core that includes ammonia molecules in non-coordinating positions, is formed. Complexes 3 and 4 were also characterized via¹¹⁹Sn{¹H} NMR and ²⁰⁷Pb NMR spectroscopy and feature signals at −280.3 ppm (¹¹⁹Sn{¹H}, 25 °C) and 1541.0 ppm (²⁰⁷Pb, 37 °C), respectively. The spectroscopic characterization of 3 and 4 extends known ¹¹⁹Sn parameters for dimeric Sn(II) aryloxides, but data for ²⁰⁷Pb NMR spectra for Pb(II) aryloxides are rare. We present also a rare VT-NMR study of a homoleptic 3-coordinate Pb(II) aryloxide. The crystal structures of 2, 3, and 4 feature interligand H⋯H contacts that are similar in number to those of related transition metal derivatives despite the larger size of the group 14 elements.