A New Type of .mu.4-Oxo-Bridged Copper Tetramer: Synthesis, X-ray Molecular Structure, Magnetism and Spectral Properties of (.mu.4-Oxo)tetrakis(.mu.-bromo)bis(.mu.-2,6-bis(morpholinomethyl)-4-methylphenolato)tetracopper(II) and (.mu.4-Oxo)tetrakis(.mu.-benzoato)bis(.mu.-2,6-bis(morpholinomethyl)-4-m

Reaction of CuBr 2 or Cu(ClO 4 ) 2 .6H 2 O and sodium benzoate with the tridentate ligand 2,6-bis(morpholinomethyl)-4-methylphenol (Hbmmk) in methanol yields two copper complexes [Cu 4 OBr 4 (bmmk) 2 ].2MeOH (1) and [Cu 4 O-(OBz) 4 (bmmk) 2 ].H 2 O (2). The compounds were characterized by single-crystal X-ray diffraction studies and are shown to contain μ 4 -oxo-bridged cluster compounds of the new type [Cu 4 OX 4 L 6 ]. 1 crystallizes in the monoclinic space group P2 1 /c with a=12.693(2) A, b=12.378(2) A, c=29.293 (6), β=96.32(3) o , V=4574.4 A 3 , and Z=4