Crystal structure and carrier transport properties of a new 3D mixed-valence Cu(i)–Cu(ii) coordination polymer including pyrrolidine dithiocarbamate ligand

Abstract

A novel mixed-valence Cu(I)–Cu(II) coordination polymer having an infinite three-dimensional (3D) structure, {[Cu^I₄Cu^II₂Br₄(Pyr-dtc)₄]·CHCl₃}_n (1) (Pyr-dtc⁻ = pyrrolidine dithiocarbamate), has been prepared and structurally characterized viaX-ray diffraction. This complex consists of 1D Cu(I)–Br chains and bridging mononuclear copper(II) units of Cu^II(Pyr–dtc)₂, which form an infinite 3D network. A magnetic study indicates that this complex includes copper(II) ions exhibiting a weak antiferromagnetic interaction (θ = −0.086 K) between the unpaired electrons of the copper(II) ions present in the diamagnetic Cu(I)–Br chains. The carrier transport properties of 1 are investigated using an impedance spectroscopy technique and flash-photolysis time-resolved microwave conductivity measurement (FP-TRMC). The impedance spectroscopy reveals that this complex exhibits intriguing semiconducting properties at a small activation energy (E_a = 0.29 eV (bulk)). The sum of the mobilities of the negative and positive carriers estimated via FP-TRMC is Σμ ∼ 0.4 cm² V⁻¹s⁻¹.