Manganese complexes coordination geometries

The characterization, redox properties, and pulse radiolysis study of manganese(III) complexes of type [MnLCy (where L = cyclam, meso-, and rac-5,7,7,12,14,14-hexamethylcyclam (tet a and tet b, respectively)) have been reported." An X-ray crystal structure of the meso-5,l,l, 2, A, A-hexamethyl-l,4,8,ll-tetraazacyclotetradecane complex shows that the coordination geometry of the tet a complex is close to octahedral with the macrocycle coordinated equatorially and the chlorides occupying irons axial sites. 

Mn Mn species [Mn(cyclam)(/.t-0)]2(C104)3. In this complex, the manganese ions are in fact crystallographically equivalent with each adopting a close to octahedral coordination geometry. 

In an analogous fashion complex 100 may be obtained by condensation of 2,6-diformylpyridine with 99 in the presence of manganese(II) or zinc(II). According to crystallographic data, the coordination geometry of 100 is distorted pentagonal bipyramidal97>. 

The simplest use of manganese is as part of a metal cofactor such as manganese(II) adenosine triphosphate, [Mn(II)ATP2-]. The metal complex is usually found as the bidentate [Mn(II)0,7-ATP2 ] (3, 4) as illustrated in Figure 1. Enzyme specificity for Mg(II), Mn(II), or Ca(II) ATP complexes is dependent on a variety of factors however, once selected, each metal apparently functions in an analogous manner. The metal ion serves two main purposes. First, based on the coordination geometry... 

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... 

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