Synthesis and thermal decomposition of copper(I) silyloxide complexes. X-ray crystal structures of [Cu(OSiPh3)]4 and [Cu(OSiPh3)(PMe2Ph)]2

Abstract Homoleptic copper(I) silyloxide complexes [Cu(OSiR 3 )] 4 [SiR 3 = SiPh 3 ( 2 ), SiPh 3 ·toluene ( 1 ) SiMe 2 Bu t ( 3 ), SiEt 3 ( 4 )] were prepared by reaction of copper(I) mesityl with equivalent amounts of silanol. Reaction of [Cu(OSiR 3 )] 4 with phosphine donors gave adduct complexes featuring lower aggregation numbers: [Cu(OSiPh 3 )(PEt 3 )] 2 ( 5 ); [Cu(OSiPh 3 ) (PMe 2 Ph)] 2 ( 6 ); [Cu(OSiMe 2 Bu t )(PPh 3 ) 2 ] ( 7 ). No reaction was observed between [Cu(OSiPh 3 )] 4 ·toluene and either sulphur donors (1,3,5-trithiane) or hard Lewis donors (THF, TMEDA). Potassium-sequestered complexes, [K(crown)][Cu(OSiPh 3 ) 2 ]· 1/2 toluene ( 8 ) and [K(crown)][Cu(OSiMe 2 Bu t ) 2 ] ( 9 ), were prepared by reaction of [Cu(OSiR 3 )] 4 with equivalent amounts of [K(crown)][OSiR 3 ]. The following complexes were characterized by single-crystal X-ray diffraction: [Cu(OSiPh 3 )] 4 ( 2 ): a tetramer featuring: (1) linear copper centres linked by bridging OSiPh 3 ligands; (2) a planar Cu 4 O 4 core with a crystallographically-imposed centre of inversion; and (3) no CuCu or CuC bonding interactions. [Cu(OSiPh 3 )(PMe 2 Ph)] 2 ( 6 ): a dimer featuring: (1) trigonal planar copper centres linked by bridging OSiPh 3 groups; (2) a planar Cu 2 O 2 P 2 core with a crystallographically-imposed centre of inversion; and (3) unsymmetrical OSiPh 3 bridging between copper centres with CuO distances differing by 0.1 A. The thermal decomposition of the [Cu(OSiR 3 )] 4 series was investigated through bulk thermolysis studies, thermal gravimetric analysis and differential scanning calorimetry. Decomposition pathways involved CuO bond homolysis leading to elemental copper.