A Tripodal Trisilanol Ligand and Its Complexation Behavior towards Cu^I, Cu^II, and Zn^II

Abstract

Abstract A three‐step synthetic route for a new tripodal branched trisilanol ligand PhSi(OSiPh 2 OH) 3 ( L H 3 ) was developed. X‐ray diffraction analysis revealed that the trisilanol crystallizes as a dimer with a cyclic hydrogen‐bonding network. The reaction of L H 3 with three equivalents of Cu n Mes n (Mes = mesityl) led to a hexanuclear compound [ L 2 Cu 6 ] ( 1 ), which was characterized by single‐crystal X‐ray diffraction analysis as well as by solution NMR spectroscopy. The crystal structure of 1 revealed that the compound features a hexagonal planar Cu I 6 ring, which is the first of its kind in an oxygen environment. Deprotonation of the ligand with n ‐butyllithium and subsequent reaction with CuBr 2 resulted in the dinuclear Cu II complex [ L′ 2 Cu 2 ][Li(THF 2 )] 2 ( 2 , THF = tetrahydrofuran), which contains a new siloxide ligand formed from L 3– by the elimination of a SiOPh 2 unit, as evidenced by X‐ray diffraction analysis. To check if the “Ph 2 SiO” elimination is a general behavior of this trisilanol, the reaction with ZnBr 2 was investigated under analogous conditions. However, this led to the isolation of [ L 2 Zn 2 ][Li(OEt)] 2 ( 3 ) without any rearrangement of the siloxide ligand.