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 [CU4I(L)(3)]I-3 (1) and [Cu-I(HL)(2)]-I-3-CH3CN (2) [HL= HN(SPPh2)(2)] have been obtained from the reaction of the adduct (HLI2)-I-. with copper(O) powder in diethyl ether solution. Compound I 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 CuMac1, and in the model compound [Cu-4(SPh)(6)](2-), have been compared with those of the [Cu-4(L)(3)](+) cation, and the geometric volumes of the Cu-4 cores have been evaluated. The results suggest that the cation [Cu-4(L)31' is a possible structural model compound for the metal site in Ace1 and Mac1 transcription factors. In compound 2, two neutral HL ligands bind a Cu-I ion in an S,S'-isobidentate chelating fashion to form a slightly distorted tetrahedral CuS4 core. The P-31 NMR spectroscopic data of compound 1 are consistent with the maintenance of its structure in solution. Moreover, phosphorus variable-temperature measurements indicate a change from a two-spin coupled AB system at 0 degrees C to an A(2) spin system at 40 degrees C. The reaction of [Cu-4(L)(3)](+) with HI, monitored by P-31 NMR spectroscopy, leads to the protonation of the complexed ligands at the CU4 core and formation of the cation [Cu-4(HL)(3)](4+). The protonation reaction is reversible: increasing the amount of organic base 1,8-bis(dimethylamino)naphthalene (DMAN) regenerates the starting cation [CU4(L)(3)](+).