On the role of anion templates for the self-assembly of octanuclear copper(I) dichalcogenophosph(in)ate clusters

Abstract

The octanuclear Cu I cubic clusters [Cu 8(S 2PPh 2) 6] 2+ ( 1) and [Cu 8(μ 8-Cl)(S 2PPh 2) 6] + ( 2) have been prepared and crystallographically characterized, and their cluster bonding modes investigated with density functional theory (DFT) calculations. Both are rare examples of metal dithiophosphinate clusters and 1 is the first example of a non anion-centered or ‘empty’ dithiophosph(in)ate Cu I 8 cube. DFT calculations indicate that the stability of the empty cluster 1 can be attributed to its strong metal–ligand interactions, with no significant Cu⋯Cu bonding interactions present. Comparison of the solid-state structures of 1, 2 and the analogous sulfide centered cluster [Cu 8(μ 8-S)(S 2PPh 2) 6] ( 3) reveals a significant contraction of the octanuclear Cu I 8 cube upon anion encapsulation. This contraction is shown, using DFT calculations, to be predominately assignable to the ionic interaction between the Cu I cations and the encapsulated anion center.