Copper(I) tert-butylthiolato clusters as single-source precursors for high-quality chalcocite thin films: Precursor chemistry in solution and the solid state

Polymeric (CuS^tBu)_∞ (1) undergoes reaction with trialkylphosphines to form the cuprous thiolato phosphine complexes [(CuS ^tBu)₄(PR₃)₂] (R = Me (2a), Et (2b)) in high yield. In contrast to 2b, in polar solvents (CH₂Cl ₂, tetrahydrofuran), complex 2a is in equilibrium with the ion pair Cu(PMe₃)₄⁺Cu₅(S^tBu) ₆^- (3) and other species such as (CuS^tBu) _x(PMe₃)₂ (x = 6 (4), 8 (5)). Clusters 2-4 were isolated analytically pure and fully characterized in solution by multinuclear nuclear magnetic resonance (NMR) spectroscopy and in the solid state by single-crystal X-ray diffraction and ³¹P magic angle spinning NMR spectroscopy, while the structure of compound 5 was determined by single-crystal X-ray diffraction. Thermal analysis (TGA/DTA) and examination of the volatile byproducts suggest stepwise phosphine loss and C-S bond cleavage by isobutene elimination as the predominant thermolysis pathways of this new Cu₂S precursor class.