The first structurally authenticated divalent lanthanide siloxide derivative, [Yb(OSiMe 2tBu) ( η2-dme) (μ-OSiMe 2tBu)] 2

Abstract

The reaction between Yb metal and Si(OH)Me 2 tBu in liquid ammonia affords, in high yield, the diamagnetic ytterbium siloxide derivative [Yb(OSiMe 2 tBu)(η 2-OSiMe 2 tBu)] 2, ( 1), (where Me = -CH 3, tBu = -C(CH 3) 3 and the dme = 1,1,2,2,-dimethoxyethane) which has been characterised by multinuclear nmr ( 29Si, 171Yb and 13C) and X-ray crystallography. The X-ray structure of crystalline ( 1) shows a distorted trigonal bipyramidal environment at each Yb centre with both bridging and terminal −OSiMe 2 tBu groups present. Exchange of these groups, at room temperature, is fast relative to the nmr time scale, with a calculated activation energy of 44 kJ mol −1 measured by 29Si NMR and a measurement of the first YbSi coupling constant.