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

A series of polynuclear gold(I) complexes with bridging diethyldithiocarbamate (Et(2)dtc) and diphosphine/triphosphine were synthesized, including [{Au-2(mu-dpb)(mu-Et(2)dtc)}SbF6](n) (1, dpb = 1,4-bis(diphenylphosphino) benzene), [Au-2(mu-dpb)(Et(2)dtc)(2)] (2), [Au-4(mu-dpn)(mu-Et(2)dtc)(3)](SbF6) (3, dpn = 1,4-bis(diphenylphosphino) naphthalene), [Au-4(mu-dpn)(mu-Et(2)dtc)(3)][Au(Et(2)dtc)(2)](SbF6)(2) (4), [Au-4(mu-dpa)(Et(2)dtc)(3)](SbF6) (5, dpa = 9,10-is(diphenylphosphino) anthracene) and [{Au-6(dpep)(2)(Et(2)dtc)(3)}{(SbF6)(3)}](n) (6, dpep = bis(2-diphenylphosphinoethyl) phenylphosphine). The structures of 3.CH2Cl2, 4.2CH(2)Cl(2), 5.2CH(2)Cl(2).H2O and 6 were characterized by X-ray crystallography. The intramolecular Au...Au distances across bridging Et(2)dtc are 2.9376(7)-2.9725(8) angstrom in 3.CH2Cl2, 2.9762(16)-3.1078(14) angstrom in 4.2CH(2)Cl(2), 2.9288(9)-3.0514(10) angstrom in 5.2CH(2)Cl(2).H2O, and 2.9236(12)-3.1914(17) angstrom 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.