Polydentate N2S2O and N2S2O2 ligands as alcoholic derivatives of (N,N'-bis(2-mercaptoethyl)-1,5-diazacyclooctane)nickel(II) and (N,N'-bis(2-mercapto-2-methylpropane)-1,5-diazacyclooctane)nickel(II)

The synthesis, structural characterization, spectroscopic, and electrochemical properties of N2S2-ligated Ni-II complexes, (N,N'-bis(2-mercaptoethyl)-1,5-diazacyclooctane)nickel(II), (bme-daco)Ni-II, and (N,N'-bis(2-mercapto-2-methylpropane)1, ,5-diazacyclooctane)nickel(II), (bme*-daco)Ni-II, derivatized at S with alcohol-containing alkyl functionalities, are described. Reaction of (bme-daco)Ni-II with 2-iodoethanol afforded isomers, (N,N'-bis(5-hydroxy-3-thiapentyl)-1,5-diazacyclooctane-O,N,N' iodide (halo = chloro or iodo), 1, and (N,N'-bis(5-hydroxy-3-thiapentyl)-1,5-diazacyclooctane iodide, 2, which differ in the utilization of binding sites in a potentially hexadentate N2S2O2 ligand. Blue complex 1 contains nickel in an octahedral environment of N(2)S(2)OX donors; X is best modeled as Cl. It crystallizes in the monoclinic space group P2(1)/n with a = 12.580(6) Angstrom, b = 12.291(6) Angstrom, c = 13.090(7) Angstrom, beta = 97.36(4)degrees, and Z = 4. In contrast, red complex 2 binds only the N2S2 donor set forming a square planar nickel complex, leaving both -CH2CH2OH arms dangling; the iodide ions serve strictly as counterions. 2 crystallizes in the orthorhombic space group Pca2(1) with a = 15.822(2) Angstrom, b = 13.171(2) Angstrom, c = 10.0390(10) Angstrom, and Z = 4. Reaction of (bme-daco)Ni-II with 1,3-dibromo-2-propanol affords another octahedral Ni species with a N2S2OBr donor set, ((5-hydroxy-3,7-dithianonadiyl)-1,5-diazacyclooctane-O,N,N',S,S')bromonickel(II) bromide, 3. Complex 3 crystallizes in the orthorhombic space group Pca2(1) with a = 15.202(5) Angstrom, b = 7.735(2) Angstrom, c = 15.443(4) Angstrom, and Z = 4. Complex 4 . 2CH(3)CN was synthesized from the reaction of (bme*-daco)Ni-II with 1,3-dibromo-2-propanol. It crystallizes in the monoclinic space group P2/c with a = 20.348(5) Angstrom, b = 6.5120(1) Angstrom, c = 20.548(5) Angstrom, and Z = 4.