Nonbonded metal

An extended Hiickel MO calculation supports the assumptions made in the above analysis in that the three t2g orbitals are indeed close together in energy and remain nearly nonbonding metal-based d-orbitals. The detailed agreement is less satisfactory the SOMO is predicted to be primarily dx2 y2 with a small dxz admixture (hybrid 6 of Table 4.13), a result that can be ruled out from our analysis of the ESR results. The EHMO overlap matrix based on the X-ray structure suggests that the molecule is much closer to C2 symmetry than to Cs. If we accept that conclusion, then dxzjdxy hybridization is less likely than dyjdxy, as we tacitly assumed above. 

It is not surprising that NO+ is so effective in accepting electron density because it not only has tt orbitals of correct symmetry, but it also has a positive charge, which makes it have a great attraction for electrons in the nonbonding metal d orbitals. 

Metal-to-ligand charge transfer (MLCT) transitions between the nonbonding metal-centred MOs and antibonding ligand-centred MOs. Such transitions are found where a metal is easily oxidised and the ligand is easily reduced. 

The orbitals which are principally nonbonding metal 3d in character are split into an e set and a /, set. The latter splitting will be discussed at some length in Chapter 11 and need not concern us too much at present. Finally, there are the a and ij anlibonding orbitals. 

A 7r-donor ligand possesses a high-lying filled orbital that can serve to interact with and destabilize a member of the nonbonding metal d set. As an iUnstrative example we present the trans and cis dioxo problem. Fignre 11(a) constmcts the n orbitals for a trans dioxo ML4 complex. Two of the three members of the t2g set can interact with two of the fonr SALCs of oxygen p AOs. Thus, one metal d and two 0x0 orbitals are left nonbonding. The orientation... 

A new bonding mode between the Cp ring and Zn has been observed for [CpZn(/u,-Cp) /u.-N(TMS)2 ZnCp]. This compound is the first example of a Cp group that bridges between nonbonded metal atoms located on the same side of the ring plane (Figure 12). 

Consideration of molecular orbital interactions suggests that it would be ideal to use a transition metal complex having at least two empty and one filled nonbonding metal valence shell orbital, i.e. a 14-elec-tion species, for observing facile bicyclization reactions shown in equations (2)-(4). This is based on assumptions that effective ir-complexation of an alkyne or an alkene with a metal complex requires the... 

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