Structures and luminescence properties of diethyldithiocarbamate-bridged polynuclear gold(i) cluster complexes with diphosphine/triphosphine

Abstract

A series of polynuclear gold(I) complexes with bridging diethyldithiocarbamate (Et₂dtc) and diphosphine/triphosphine were synthesized, including [{Au₂(μ-dpb)(μ-Et₂dtc)}SbF₆]_n (1, dpb = 1,4-bis(diphenylphosphino)benzene), [Au₂(μ-dpb)(Et₂dtc)₂] (2), [Au₄(μ-dpn)(μ-Et₂dtc)₃](SbF₆) (3, dpn = 1,4-bis(diphenylphosphino)naphthalene), [Au₄(μ-dpn)(μ-Et₂dtc)₃][Au(Et₂dtc)₂](SbF₆)₂ (4), [Au₄(μ-dpa)(Et₂dtc)₃](SbF₆) (5, dpa = 9,10-bis(diphenylphosphino)anthracene) and [{Au₆(dpep)₂(Et₂dtc)₃}{(SbF₆)₃}]_n (6, dpep = bis(2-diphenylphosphinoethyl)phenylphosphine). The structures of 3·CH₂Cl₂, 4·2CH₂Cl₂, 5·2CH₂Cl₂·H₂O and 6 were characterized by X-ray crystallography. The intramolecular Au⋯Au distances across bridging Et₂dtc are 2.9376(7)–2.9725(8) Å in 3·CH₂Cl₂, 2.9762(16)–3.1078(14) Å in 4·2CH₂Cl₂, 2.9288(9)–3.0514(10) Å in 5·2CH₂Cl₂·H₂O, and 2.9236(12)–3.1914(17) Å in 6, implying significant aurophilic interactions. These gold(I) complexes exhibit intense photoluminescence properties in solid state. Upon lowering the temperature from 298 to 77 K, complexes 5 and 6 exhibit an obvious red-shift from 536 nm to 589 nm for 5 and from 538 nm to 564 nm for 6, implying significant luminescence thermochromism due to thermal contraction upon cooling.