Square-pyramidal five-coordinate

Spot tests, 1, 552 Square antiprisms dodecahedra, cubes and, 1, 84 eight-coordinate compounds, 1,83 repulsion energy coefficients, 1, 33, 34 Square planar complexes, 1,191, 204 structure, 1, 37 Square pyramids five-coordinate compounds, 1,39 repulsion energy coefficients. 1,34 Squares... 

The yellow Co(II)-cyanide solid complex contains square-pyramidal five-coordinated Co(CN). The green ion in solution is possibly Co(CN)5H20 with very weak H2O coordination in the sixth axial position. It is an important inner-sphere reductant (Prob. 8 of Chap. 5, and Tables 5.3 and 5.7). Generally... 

Hydrolysis of Pd(MeCOCHMe)2 in aqueous methanol is considered to involve Pd(0,0-MeCOCHCOMe)(0-MeCOCHCOMe)(MeOH) as an intermediate from which the monodentate acetylacetonate ligand is then solvolyzed.221 Subsequent studies on Lewis base complexes of palladium bis(diketonate) complexes provide ample support for the proposed intermediate. A pulse radiolysis study of the kinetics of aquation of M(MeCOCHCOMe) " (M = Cr, Co) indicates that an 17,-172 equilibrium involving one or more of the acetylacetonate ligands occurs, associated with an acid-catalyzed removal of the monodentate ligand.222 Treatment of Cu(MeCOCHCOMe)2 with picric acid in moist dichloromethane affords a partially hydrolyzed material, Cu(MeCOCHC-0Me)(H20)2[C6H2(N02)30], proposed to contain square pyramidal five-coordinate copper with the oxygen atom from the picrate moiety at the apex.223... 

Among the various structural types (Figure 4), square four-coordinate, square pyramidal five-coordinate and octahedral six-coordinate complexes are most commonly found in metallopor-phyrins, especially for the first row transition metal series. 

Loss of a ligand to form a square pyramidal, five-coordinate transition state (or possibly an intermediate if the compound is at a local minimum on the energy curve) ... 

Square Pyramidal Five-Coordinate SPY-5 Diastereomers of the SPY-5 complex with a four-legged piano stool geometry having an apical half-sandwich Cp were found for M(Cp)(CO)2(/V-A "), where N-N is a chiral unsymmetrical bidentate Schiff base of pyridine-2-aldehyde and (—)-a-phenylethyamine.57... 

The structure and chemistry of the square-pyramidal five-coordinate and pseudo-octahedral six-coordinate [TcvO]3+ complexes are dominated by the strong tetragonal distortion induced by the multiply bonded oxo ligand. The d orbital energy levels in C4u symmetry are in... 

Bidentate ligands containing OS donors, particularly in conjunction with carboxylate moieties, form strong complexes at pH values near the p/y, value for the thiol.584,602,687-689 The reduction of Viv to V111 by cysteine methyl ester in water has been found to be enhanced in the presence of amino polycarboxylates.690 The ligand 2-mercapto-4-methylphenol forms a square-pyramidal five-coordinate complex with the vanadyl cation (150) the reported crystal structure is of the cis isomer.691 The bidentate ligand 2-aminocyclopent-l-ene-l-carbodithioic acid forms non-oxo-Viv complexes based on spectroscopic studies and chemical precedence, an eight-coordinate vanadium atom is inferred.692... 

Complexes containing a TcO " core show an octahedral six-coordinated or a square pyramidal five-coordinated spatial configuration complexes containing a TcOj core form octahedral six-coordinated complexes. In the presence of suitable ligands, other cores and complexes of lower oxidation states (IV, III, I) may be achieved (Jones and Davison 1982). 

Galactose oxidase (GO) catalyses the two-electron oxidation of primary alcohols to aldehydes. It contains a single type II copper centre. The enzyme employs the metal and a protein radical cofactor to effect the chemistry. The crystal structure shows a square pyramidal five-coordinate copper site with the metal coordinated by two histidines, two tyrosines and a water or acetate ligand. The equatorial tyrosine, Tyr272, has an interesting crosslink to a cysteine group ortho to the tyrosine oxygen. 

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