Synthesis and Structures of d10–d10M2(μ‐dppm)2 Complexes with Sensitive Metal–Metal Distances in Response to the Binding of Sigma Donors

Abstract

Diphosphine‐bridged dicopper(I) acetate complexes [Cu2(μ‐dppm)2(μ‐OAc)]X ( 2X; X− = , ) and [Cu2(μ‐dppm)2(μ‐OAc)(MeCN)]X ( 4X) were prepared and the structures of 2(PF6 ) and 4(PF6 ) determined by X‐ray crystallography. The ground‐state geometries of [Cu2(μ‐dppm)2(μ‐OAc)]+ and [Cu2(μ‐dppm)2(μ‐OAc)(L)]+ (L = py, MeCN, THF, acetone, MeOH) were also obtained using density functional theory (DFT). The increased Cu–Cu distances found experimentally and theoretically by comparing the structures of cation [Cu2(μ‐dppm)2(μ‐OAc)]+ and its derivatives [Cu2(μ‐dppm)2(μ‐OAc)(L)]+ reflect the binding of various sigma donors (L). When using [Cu2(μ‐dppm)2(μ‐OAc)]+ as a structure sensor, the electron‐donating strength of a sigma donor can be quantitatively expressed as a DFT‐calculated Cu–Cu distance with the relative strength in the order py > MeCN > THF > acetone > MeOH, as determined.