Nickel(II) in an N4S donor environment:: An unprecedented alcoholysis reaction through the activation of a carbon-nitrogen single bond

Pentadentate N4S ligands based on methyl 2-aminocyclopent-1-ene-1-dithiocarboxylate with flexible pyrazolyl arms (Me(2)pzCH(2))(2)NC2H3RNHC5H6CSSCH3 (R = H, Hmmecd and R = CH3, Hmmpcd) undergo a nickel(II)induced alcoholysis reaction through the activation of a saturated C-N bond linkage. The products obtained are square-planar complexes 1-4 containing a modified ligand structure possessing an N3S donor set and a pendant arm that holds the alkoxy group provided by the solvent. [Ni(N3S)-CH2OMe]ClO4 1 crystallizes in the triclinic space group P (1) over bar with a = 10.4886(5) Angstrom, b = 10.706(1) Angstrom, c = 11.487(1) Angstrom, alpha = 108.784(4)degrees, beta = 108.887(6)degrees, gamma = 95.139(6)degrees, V = 1128.0(4) Angstrom(3), and Z = 2; while [Ni(N3S)'-CH2 OPrn]ClO4 4 has the monoclinic space group P2(1)/n with a = 8.875(2) Angstrom, b = 18.629(2) Angstrom, c = 15.399(2) Angstrom, beta = 91.37(2)degrees, V = 2545(1) Angstrom(3), and Z = 4 per unit cell. Complexes 1-4 with acyclic ligand environments have interesting electrochemical behavior in acetonitrile, involving a reversible Ni(II)/Ni(I) reduction, E-1/2 Ca -1.0 V, and a Ni(II)/Ni(III) irreversible oxidation, E-pa ca. 1.0 V vs Ag/AgCl as the reference. The coulometrically reduced solution of 2 displays a rhombic EPR spectrum at 77 K characteristic of nickel(I) with g(1) = 2.217, g(2) = 2.170, and g(3) = 2.054.