DIOXOMOLYBDENUM(VI) COMPLEXES OF NEW BINUCLEATING SCHIFF-BASES DERIVED FROM METHYLENE-BIS(SALICYLALDEHYDE) OR DITHIO-BIS(SALICYLALDEHYDE) AND VARIOUS AMINES
Mr. Maurya et al., DIOXOMOLYBDENUM(VI) COMPLEXES OF NEW BINUCLEATING SCHIFF-BASES DERIVED FROM METHYLENE-BIS(SALICYLALDEHYDE) OR DITHIO-BIS(SALICYLALDEHYDE) AND VARIOUS AMINES, Polyhedron, 12(22), 1993, pp. 2731-2736
The syntheses of binuclear dioxomolybdenum(VI) complexes of the type [
(MoO2)2L], where L is a flexibly-bridged hexadentate tetraanionic Schi
ff base derived from the condensation of methylene- or dithio-bis(sali
cylaldehyde) with o-aminophenol, 2-aminoethanol, 2-amino-2-methyl prop
anol or 1-amino-2-propanol, are reported. The IR and NMR spectral data
suggest an oligomeric structure in which each molybdenum ion achieves
a pseudo-octahedral structure via Mo=O---Mo bridging. Treatment of [(
MoO2)2L] with pyridine leads to the formation of [MoO2)2L(py)2] in whi
ch pyridine binds at the sixth labile binding sites in both [MoO2]2+ u
nits. [(MoO2)2L(py)2] is readily convertable into [(MoO2)2L] at ca 180
-degrees-C in a single endothermic step, as seen from their DTA analys
is. The pyridine adducts show two IR absorptions at ca 900 cm-1, attri
butable to a cis-MoO2 structure, whereas the oligomeric complexes usua
lly show one intense nu(Mo=O) band at 910-938 cm-1 and a broad but str
ong band at ca 820 cm-1 due to a weakened nu(Mo=O) band as a result of
Mo=O --> Mo interactions.