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 (Me2pzCH2)2NC2H3RNHC5H6CSSCH3 (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 P1h with a ) 10.4886(5) Å, b ) 10.706(1) Å, c ) 11.487(1) Å, R ) 108.784(4)°, â ) 108.887(6)°, γ ) 95.139(6)°, V ) 1128.0(4) Å3, and Z ) 2; while [Ni(N3S)′-CH2 OPr]ClO4 4 has the monoclinic space group P21/n with a ) 8.875(2) Å, b ) 18.629(2) Å, c ) 15.399(2) Å, â ) 91.37(2)°, V ) 2545(1) Å3, 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, E1/2 ca. -1.0 V, and a Ni(II)/Ni(III) irreversible oxidation, Epa 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 g1 ) 2.217, g2 ) 2.170, and g3 ) 2.054.