Copper(I) Siloxides – Aggregated Solid‐State Structures, Cu–Cu Interactions and Dynamic Solution Behavior

Reaction of the siloxane‐diols HO(Ph 2 SiO) 2 H, 1,1,3,3‐tetraphenyldisiloxane‐1,3‐diol (L 1 H 2 ), HO( i Pr 2 SiO) 2 H, 1,1,3,3‐tetraisopropyldisiloxane‐1,3‐diol (L 2 H 2 ), and HO(Ph 2 SiO) 3 H, 1,1,3,3,5,5‐hexaphenyltrisiloxane‐1,5‐diol (L 3 H 2 ) with two equivalents of Cu n Mes n led to octanuclear compounds [Cu 8 L 1 4 ] ( 1 ), [Cu 8 L 2 4 ] ( 2 ), and [Cu 8 L 1 2 L* 2 ] [L* = O(Ph 2 SiO) 4 ] ( 3 ), which were characterized by single‐crystal X‐ray diffraction analysis as well as by solution NMR spectroscopy. The crystal structures revealed that all the compounds are composed of Cu 4 O 4 moieties featuring short Cu–Cu distances that can be discussed in terms of cuprophilic interactions. Two such units are linked via four disiloxane units in 1 and 2 , in 3 they are connected by two equivalents of (L 1 ) 2– . Formation of 3 required disproportion of a trisiloxane‐1,5‐diolate to give a disiloxane‐1,3‐diolate and a tetrasiloxane‐1,7‐diolate, and thus indicates that siloxane units are not inert under the synthetic conditions employed. NMR spectroscopic investigations of the structure of 1 in solution revealed an equilibrium, presumably with [Cu 4 L 2 2 ] fragments. Crystallization of a structural isomer of 3 indicates a shallow potential energy surface for this compound.