Spectroscopy and structures of two complete families, one mononuclear, the other binuclear, of 1 : 2 CuX : dptu stoichiometry (X = Cl, Br, I; ‘dptu’ = N,N′-diphenylthiourea)

Abstract

Crystallization of the copper(I) halides (CuX; X = Cl, Br, I) with N,N′-diphenylthiourea (‘dptu’ = (PhNH)₂CS) in 1 : 2 ratio from acetonitrile solution in ambient conditions yields a mononuclear isomorphous series of complexes of the form [XCu(dptu)₂]·H₂O, an unusually complete array, with the central copper atoms in quasi-trigonal planar environments, as shown by single crystal X-ray studies, in turn providing a platform for comparative spectroscopic studies. Under anhydrous conditions, anhydrous compounds may be obtained, a full series again being accessible, but now of the binuclear form [(dptu)XCu(μ-S-dptu)₂CuX(dptu)], the chloride being a bis(acetonitrile) solvate, the isomorphous bromide and iodide pair being unsolvated. A (solvated) sulfate salt is found to be of the form [Cu(dptu)₂]₂(SO₄), providing a novel example of a copper(I) atom being (quasi-)linearly coordinated by the pair of unidentate (dptu) sulfur ligands, Cu–S 2.1770(5), 2.1811(5) Å, S–Cu–S 162.18(2)°. The ν(CuX) vibrational frequencies are assigned in the far-IR spectra of [XCu(dptu)₂]·H₂O (X = Cl, Br, I) at 274, 207, and 190 cm⁻¹ respectively. The broadline static ⁶⁵Cu NMR spectra of [Cl₂Cu₂(dptu)₄]·2CH₃CN and [X₂Cu₂(dptu)₄] (X = Br, I) have been recorded at 9.4 and 7.05 T, and the spectra have been analysed to yield the ⁶⁵Cu nuclear quadrupole coupling and chemical shift parameters. The ^63,65Cu nuclear quadrupole resonance frequencies of [XCu(dptu)₂]·H₂O (X = Cl, Br, I) have also been measured, and the resulting ⁶⁵Cu quadrupole coupling constants are ca. 4× those of the dimeric [X₂Cu₂(dptu)₄] compounds.