Molecular and Electronic Structure of Cyclic Trinuclear Gold(I) Carbeniate Complexes: Insights for Structure/Luminescence/Conductivity Relationships

An experimental and computational study of correlations between solid-state structure and optical/electronic properties of cyclotrimeric gold­(I) carbeniates, [Au₃(RNCOR′)₃] (R, R′ = H, Me, ⁿBu, or ^cPe), is reported. Synthesis and structural and photophysical characterization of novel complexes [Au₃(MeNCOⁿBu)₃], [Au₃(ⁿBuNCOMe)₃], [Au₃(ⁿBuNCOⁿBu)₃], and [Au₃(^cPeNCOMe)₃] are presented. Changes in R and R′ lead to distinctive variations in solid-state stacking, luminescence spectra, and conductive properties. Solid-state emission and excitation spectra for each complex display a remarkable dependence on the solid-state packing of the cyclotrimers. The electronic structure of [Au₃(RNCOR′)₃] was investigated via molecular and solid-state simulations. Calculations on [Au₃(HNCOH)₃] models indicate that the infinitely extended chain of eclipsed structures with equidistant Au--Au intertrimer aurophilic bonding can have lower band gaps, smaller Stokes shifts, and reduced reorganization energies (λ). The action of one cyclotrimer as a molecular nanowire is demonstrated via fabrication of an organic field effect transistor and shown to produce a p-type field effect. Hole transport for the same cyclotrimerdoped within a poly­(9-vinylcarbazole) hostproduced a colossal increase in current density from ∼1 to ∼1000 mA/cm². Computations and experiments thus delineate the complex relationships between solid-state morphologies, electronic structures, and optoelectronic properties of gold­(I) carbeniates