Crystal Structures and Vibrational Spectroscopy of Copper(I) Thiourea Complexes

G.A. Bowmaker, J.V. Hanna, C. Pakawatchai, Brian Skelton, Y. Thanyasirkul, Allan White

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82 Citations (Scopus)

Abstract

Several synthetic strategies using copper(I) starting materials or copper(II) compounds and an in situ sulfite reductant have been used to systematically explore the chemistry of copper(I) complexes with thiourea and substituted thiourea ligands. This has resulted in the discovery of several new complexes and methods for the bulk synthesis of some previously reported complexes that had been prepared adventitiously in small quantity. The new complexes are (tu = thiourea, dmtu = N,N′-dimethylthiourea, etu = ethylenethiourea): [I4Cu4(tu)6]·H2O, [Cu4(tu)10](NO3)·tu·3H2O, [BrCu(dmtu)3], [ICu(dmtu)3]2, [BrCu(etu)2]2, [ICu(etu)2], [ICu(etu)2]3. [I4Cu4(tu)6]·H2O has an adamantanoid structure, with four terminal iodide ligands and six doubly bridging tu ligands. In contrast to this, [Cu4(tu)10](NO3)·tu·3H2O contains a tetranuclear cluster in which four of the tu ligands are terminal and the other six are doubly bridging. [BrCu(dmtu)3] is a mononuclear complex with tetrahedral coordination of copper by one bromide and three dmtu ligands, whereas [Cu(dmtu)3]2I2 has a centrosymmetric dimeric cation with two uncoordinated iodides, four terminal dmtu and two doubly bridging dmtu ligands, [(dmtu)2Cu(μ-S-dmtu)2Cu(dmtu)2]I2. A reversal of this monomer to dimer trend from bromide to iodide is seen for the etu counterparts: [BrCu(etu)2]2 is a centrosymmetric dimer with two doubly bridging etu ligands, [(etu)BrCu(μ-S-etu)2CuBr(etu)], whereas [ICu(etu)2] is a trigonal planar monomer, although the novel [I3Cu3(etu)6] is also defined. Infrared and Raman spectra of the synthesized complexes were recorded and the metal−ligand vibrational frequencies have been assigned in many cases. The results confirm previously observed correlations between the vibrational frequencies and the corresponding bond lengths for complexes of the unsubstituted tu ligand. A mechanochemical/infrared method was used to synthesize [I3Cu3(etu)6] from CuI and etu, and to demonstrate the polymorphic transition from [ICu(etu)2] to [I3Cu3(etu)6].
Original languageEnglish
Pages (from-to)350-368
JournalInorganic Chemistry
Volume48
Issue number1
DOIs
Publication statusPublished - 2009

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