Manganese complexes octahedral compounds

In the cobalt complex, each cobalt atom has a trigonal bipyramidal coordination geometry, whereas, in the manganese complex, each manganese atom is octahedrally coordinated. In both cases, the equatorial carbonyl groups are bent towards the central mercury atom. The structures of the related compounds... 

Unfortunately, ( PDI)Mn(THF)2 exhibited little activity for the hydrogenation of alkenes or [2 + 2] cyclization of dienes. In an attempt to synthesize an active bis(imino)pyridine manganese precatalyst, alternative reduction conditions were explored. Sodium amalgam reduction of ( PDI)MnCl2 in pentane yielded the red bis(chelate) complex ( PDI)2Mn. X-ray diffraction established a cis-divacant octahedral compound where one imine arm on each of the chelates is dissociated from the metal center. The metrical parameters from X-ray diffraction in conjunction with SQUID magnetic and EPR spectroscopic data established that the overall S = 3/2 compound is best described as a high-spin Mn(II) species (Sy = 5/2) with two bis(imino)pyridine radical anions. 

In general, manganese(III) compounds are coloured, and the complexes are octahedral in shape with four d electrons, the colour is attributable in part to d-d transitions. 

The structure of the active component, manganese pyrophosphate, has been reported in the literature (24). It is layer like with planes of octahedrally coordinated Hn ions being separated by planes of pyrophosphate anions (P20y ). Examination of models of this compound gave calculated Hn-Hn thru space distances of 3.26 and 3.45 angstroms, a metal-metal distance close to that found for binuclear dibridged peroxo- and superoxo- complexes of cobalt ( ). 

Tetrahedral [Mn(NCSe)4] and octahedral [Mn(NCSe)g] anions are known (162, 295, 6i7, 655, 656), and [Re2(NCSe)8] has been tentatively identified (377). There seem to be no reports of similar Tc compounds, nor indeed of any mixed-ligand selenocyanate complexes of either technetium or rhenium. Some mixed-ligand complexes of manganese(II) selenocyanate have been prepared, and in every case so far described the selenocyanate is N-bonded. Analogous to the thio-... 

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