Synthesis and characterisation of Polyoxometallate Organic Fragments (POMS), Manganese and Bimetallic complexes for industrial chemical catalysis

Abstract

This report contains synthesis and characterisation of polyoxometallate organic fragments, manganese and bimetallic complexes which can be used in heterogeneous catalysis. Polyoxometallate organic fragments were obtained by a conventional mixed-solvent solution method and found to be of the type Na1.5H4.5[CH3)4N]2{[M](LnX)}.9H2O} where {M=Mn(acac)3 or K4[Fe(CN)6 ] , L= As or Se or Si, X=Mo11O43or W11O43and n is a variable. The mangansese complexes prepared include potassium trioxalatotomanganese (III) which rapidly decomposes from the raddish needle shaped crystals to white crystals on exposure to light and black crystals of tris(acetylacetonato) manganese (III) which was later used in synthesis of polyoxometallate fragments. In addition to the above complexes, bimetallic complexes were also discussed i.e. thiocyanate bridged complexes of type[Ni(L)5][Co(NCS)4] with cation ML6[M=Ni, L=ethylenediamine] and anion [Co(NCS)4] 2-.Cyano bridged complexes from reactions between [M(L)]2+[M= Ni] and [Fe(CN)6]3-were also described. Characterisation of these complexes was achieved with the use of the UV-Vis spectroscopy and the spectrum of tris(acetylacetonate) manganese(III) had the main band peaks at 325 nm and 520 nm, Na1.5H4.5[CH3)4N]2{[Mn(acac)3](As2w11O43)}.9H2O} had main peaks at 520nm and 512nm,{[Fe(CN) 6]2[Ni (anil)2]3} had main peaks at 420nm and 620nm, etc.