Diamagnetic complexes, reactivity

Mixed O- and N-donor ligands. Studies of the reactivities of co-ordinated ligands have shown that bis-salicylaldoxime chelates of Ni, Pd, and Cu react with AlPh3 in benzene to yield grey diamagnetic complexes (12).35 Dimethylglyoxime complexes undergo similar reactions (see below). 

The number of electrons in the valence shell of each complex or intermediate is shown. This illustrates the important rule that diamagnetic complexes of the transition metals from Groups IV—VIII have either sixteen or e hteen electrons in their outer shell. This rule is well known for stable complexes, being a modification of the inert gas rule. In addition Tolman 38) has recently pointed out that it works quite well for reactive intermediates or transition states. Exceptions are known, however. 

These compounds perform a dual function in synthesis procedures. The introduction of a complex anion assists in the stabilization of the desired product and the generation of unique intermediates by chloride displacement, eg, silver hexafluorophosphate, AgPF, forms adducts with neutral diamagnetic organometaHics which can act as controUed sources of highly reactive cations (29). Silver hexafluoroantimonate, AgSbF, is an electrophilic... 

Most of the studies of the reactivity of this oxidation state have been carried out with these types of complexes. The low spin d Ni(IV) resembles Co(III) in being diamagnetic, substitution inert and capable of resolution into optical isomers. Reductions are outer-sphere when Co(edta), ascorbate and Co(phen)3+ Ref. 269 are used, intermediate Ni(III) species are detected and characterized. Oxidation of Co(edta) by Ni (S-Me2L) + or Ni (S-MejL), L = 12, R = R]=CH3i R2 = H, produces a =10% excess of (+)-... 

The titanium complex is diamagnetic which, if the titanium is present as Tin, indicates a strong exchange interaction. It reacts with C02 forming THF.Ti(OOCH)2MgCl15, which yields formic acid on hydrolysis and ethyl formate with C2H5I. This indicates that the hydrogen is bound to the carbon atom of the co-ordinated C02 molecule as in (7) or (8). The formation of C—H bonds implies the presence of reactive metal-hydride intermediates.76... 

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