Syntheses, Characterization, and Reactivities of (μ‐η2:η2‐Disulfido)dicopper(II) Complexes with N‐Alkylated cis,cis‐1,3,5‐Triaminocyclohexane Derivatives

Abstract

AbstractThree novel (disulfido)dicopper(II) complexes with N‐alkylated cis,cis‐1,3,5‐triaminocyclohexane derivatives, [Cu2(S2)(R3TACH)]X2 [(R, X) = (Et, CF3SO3) (1), (iBu, SbF6) (2), and (Bn, SbF6) (3)], have been synthesized and characterized by elemental, electrochemical, and X‐ray structure analyses, and electronic absorption, IR, ESI mass, and resonance Raman spectroscopic methods. The X‐ray crystal structures indicate that the two sulfur and two copper atoms of these complexes form a Cu2(S2) structure with slight bending of the two planes defined by the CuS2 plane at angles of 166.12° (the individual bending angles are 175.56° for 1a and 156.67° for 1b), 154.74°, and 180° for 1, 2, and 3, respectively. The UV/Vis absorption spectra of 1, 2, and 3 have a sharp band at ca. 360 nm with a broadened shoulder at 400–480 nm and low intensity d–d bands in the range 666–671 nm. The resonance Raman spectra of the complexes have peaks assignable to a ν(S–S) band at 483–484 cm–1. The complexes have reduction waves at –974 to –946 vs. [Fe(C5H5)2]/[Fe(C5H5)2]+ for 1, –993 to –976 for 2, and –948 to –928 mV for 3. These values are in a low‐potential region relative to bis(μ‐OH)dicopper complexes with R3TACH. This may be explained by the occurrence of strong π‐donation from the disulfide ligands as observed for previously reported (disulfido)Ru complexes. Compounds 1, 2, and 3 react with PPh3 to give S=PPh3 in yields of 65 ± 3.5, 76 ± 1, and 50 ± 2 %, respectively. These results are discussed in terms of the relationship between the dihedral angles in the Cu2(S2) core and the reactivity of S22–. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)