Synthesis and Reactivity of Trigonal Copper(i) Compounds. Crystal Structure of Bis(tetrahydropyrimidine-2-Thione)copper(i) Bromide

Reaction of monovalent copper halides with excess tetrahydropyrimidine-2-thione (thpmtH2) in acetonitrile results in the formation of three-coordinate monomer products of formula Cu(thpmtH2)2X. The crystal and molecular structure of the bromo complex is reported and discussed with respect to analogous copper(I) complexes. The compound crystallizes in the tetragonal system, space group, P41212 with a = 8.005(1), c = 21.31(1) Å, and Z = 4. The two Cu-S bonds are 2.215(4) Å and the Cu-Br bond distance is 2.405(2) Å, the interbond angles around copper being exactly 360°. Reactivity of the title compound as well as of its iodo counterpart towards Lewis bases was also investigated; the two compounds react readily, in stoicheiometric amounts, with tertiary phosphine and arsine ligands forming monomeric four-coordinate Cu(I) species, the structures of which were deduced by spectroscopic measurements.