PREPARATION AND CHARACTERIZATION OF COBALT(II) COMPLEXES DERIVED FROMHEXADENTATE TRIPOD LIGAND AND THEIR POTENTIALS AS EPOXIDATION CATALYSTS

The ligand N,N,N',N'-tetrakis (1-hydroxymethyl-2-benzimidazolymethyl)- 1,2- ethanediamine (HMEDTB) (L) has been prepared and characterized by elemental analyses and spectral data. Its reaction with cobalt(II) ch loride hexahydrate, or cobalt(II) nitrate hexahydrate in the molar rat io of 1:2 in acetonitrile afforded the complexes [Co(L)](2+) 2NO(3)(-) (1), and [Co-2(L)Cl-2](2+) 2Cl(-) (2), respectively. Elemental analys es and spectral data on compound (1) show it to be a mononuclear catio nic cobalt(Il) complex in an octahedral geometry, with two nitrate ion s as counterions. Similar data on compound (2) reveal the presence of a cationic dicobalt complex with bridging hydroxide in possibly a trig onal bipyramidal geometry. Compounds(1) and (2) catalysed the epoxidat ion of styrene in 53.8 and 34.3% yields, respectively.