Copper(I) complexes with a Cu4S6- and CuS4-type core obtained from the reaction of copper(0) with HN(SPPh2)(2)center dot I-2

The copper(I) compounds [CuI4(L)3]I3 (1) and [CuI(HL)2]- I3·CH3CN (2) [HL = HN(SPPh2)2] have been obtained from the reaction of the adduct HL·I2 with copper(0) powder in diethyl ether solution. Compound 1 contains a tetrahedron of Cu atoms with three anionic L ligands coordinated to the coppers through the sulfur atoms to build a Cu4S6 core. The mean Cu–Cu and Cu–S bond lengths related to the Cu4S6 core in copper-loaded transcription factors CuAce1 and Cu- Mac1, and in the model compound [Cu4(SPh)6]2–, have been compared with those of the [Cu4(L)3]+ cation, and the geo- metric volumes of the Cu4 cores have been evaluated. The results suggest that the cation [Cu4(L)3]+ is a possible struc- tural model compound for the metal site in Ace1 and Mac1 transcription factors. In compound 2, two neutral HL ligands bind a CuI ion in an S,S'-isobidentate chelating fashion toform a slightly distorted tetrahedral CuS4 core. The 31P NMR spectroscopic data of compound 1 are consistent with the maintenance of its structure in solution. Moreover, phospho- rus variable-temperature measurements indicate a change from a two-spin coupled AB system at 0 °C to an A2 spin system at 40 °C. The reaction of [Cu4(L)3]+ with HI, moni- tored by 31P NMR spectroscopy, leads to the protonation of the complexed ligands at the Cu4 core and formation of the cation [Cu4(HL)3]4+. The protonation reaction is reversible: increasing the amount of organic base 1,8-bis(dimethylam- ino)naphthalene (DMAN) regenerates the starting cation [Cu4(L)3]+.