CONDENSATION-REACTIONS OF COBALT AMINO-ACID COMPLEXES WITH FORMALDEHYDE - PREPARATION AND CRYSTAL-STRUCTURES OF COBALT COMPLEXES CONTAININGNEW HEXADENTATE, PENDANT-ARM MACROCYCLIC AND ACYCLIC LIGANDS

The reaction of cobalt(III) complexes alpha-cis-[Co(EDDA)L](+) contain ing both amino acid (EDDA, ethylenediamine: N,N'-diacetate) and bident ate amine ligands (L = en, ethylenediamine; Men, N-methylethylenediami ne; BEE N,N'-diethylethylenediamine; DEE, N,N-diethylethylenediamine) with formaldehyde under basic conditions has been investigated. For L = en, the product is [Co(L-1)](+), which contains a macrocyclic ligand (L-1 = 1,4-bis(carboxymethyl)-6,13-dioxacyclam) formed by linking the primary nitrogens on the en ligand with the secondary nitrogens on th e EDDA ligand through two CH2OCH2 bridges. For L = Men and DEE, which each contain only one primary nitrogen, the reaction gives complexes [ Co(L-2)](+) and [Co(L-3)](+) bearing hexadentate acyclic ligands (L-2 = methyl)-11-ethyl-6-oxa-1,4,8,11-tetraazatridecane; L-3 = is(carboxym ethyl)-6-oxa-1,4,8,11-tetraazadodecane) each resulting from formation of one new CH2OCH2 linkage. All complexes have been characterized by H -1 and C-13 NMR, IR, and UV-visible spectroscopy and cyclic voltammetr y. The X-ray crystal structures of [Co(L-1)]Cl . 3H(2)O and [Co(L-3)]P F6 . NH4PF6 . H2O have been determined. [Co(L-1)]Cl . 3H(2)O is monocl inic, P2(1)/n, with a = 14.792(3) Angstrom, b = 3.766(1) Angstrom, c = 16.520(4) Angstrom, beta = 99.54(2)degrees, V = 1871.5(6) Angstrom(3) , Z = 4, R = 0.042: [Co(L-3)]PF6 . NH4PF6 . H2O is monoclinic, P2(1)/n , with a 13.353(6) Angstrom, b = 11.595(2) Angstrom, c = 16.900(5) Ang strom, beta = 95.59(3)degrees, V = 2604(2) Angstrom(3), Z = 4, R = 0.1 07.