Complexes with coordination number seven

A nomenclature which is sometimes used to distinguish these three forms of seven-coordination is to proceed down the axes indicated by arrows in Figs. 3.14-3.16 (these are the axes of highest symmetry) and to list the number of ligands lying in planes perpendicular to those axes. In this nomenclature the geometries are called the 1 5 1 (Fig. 3.14), 1 4 2 (Fig. 3.15) and 1 3 3 (Fig. 3.16) modes of seven-coordination. 

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Following Co(II) complexes, the most frequently found hepta-coordinate structures among 3d metals are those of Mn(II) complexes. Based on literature data, 21 X-ray analyses of Mn(II) complexes with coordination number seven have been reported so far. They include... 

Complexes of 3d Metals with Coordination Number Seven and Macrocyclic 2,6-Diacetylpyridine and Some Related... 

Most of the nickel compounds in the solid state and almost all in aqueous solution contain the metal in the oxidation state +2, which, by consequence, can be considered the ordinary oxidation state for nickel in its compounds. The electronic structure and stereochemistry of nickel(II) were reviewed in 1968.6 The most stable electronic configuration of the free Ni ion is [Ar]3d8 which is also the ground state configuration in its complexes. The overwhelming majority of nickel(II) complexes have coordination numbers of four, five and six. Complexes with coordination numbers of three, seven and eight are still quite rare. 

Stereochemical non-rigidity, especially if of fluxional character, seems likely to be consistently characteristic of complexes with coordination numbers of seven or greater. All seven-coordinate complexes so far investigated by nmr techniques have shown ligand-atom equivalence even though there is no plausible structure for a seven-coordinate complex that would give static or instantaneous equivalence. Thus, ReF7 and IF7, for example, are presumed to be fluxional. 

Complexes oe 3d Metaes with Coordination Number Seven and Macrocyceic 2,6-Diacetyepyridine and Some Reeated... 

The most common coordination numbers for transition metal complexes of relevance in catalysis are four, five, and six. However, a few metal complexes with coordination numbers two, three, and seven are also of relevance. Structures 2.3-2.8 show the common coordination geometries for coordination numbers four, five, and six. 

Until several years ago, most of the known compounds of Wn were monomeric complexes, which exhibit mainly coordination number seven, and cluster compounds containing the octahedral W6 nucleus with W—W single bonds. The most important advance in the chemistry of W11 has undoubtedly been the preparation and characterization of dinuclear compounds containing W—W quadruple bonds. 

Iridium(III) complexes (d6) are diamagnetic and low-spin ((f,). The coordination number of most known iridium(III) complexes is six, though a few five- and seven-coordinate complexes have been reported. Iridium(III) forms complexes with soft ligands. The [Ir(H20)6]3+ ion is unknown no solid iridium(III) complexes with coordinated H20 groups are known with the exception of a few aquachloro complexes.197... 

Coordination number seven. The seven-coordinate polyhedron of maximum symmetry is the pentagonal bipyramid (Figure 1) with sp d (xy,x y, z ) hybridization. This polyhedron is commonly found in seven-coordinate complexes. Other polyhedra found in seven-coordinate complexes include the capped octahedron with sp d z, xz,yz) or sp d (z, xy,x - y ) hybridization and the 4-capped trigonal prism with sp d (z, xy,xz) or sp d (x - y, .yy,j z) hybridization. Note that the choice... 

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