Zirconium complexes pyridine oxide

The [2+2] reactions of the zirconium-imido compounds with alkynes and alkenes occurs by a mechanism similar to that for the [2+2] reactions of carbenes with alkynes and alkenes. The alkene or alkyne first binds to an open coordination site at the metal, and this coordination is followed by conversion of the alkyne or alkene complex to the metallacyhc product (e.g. Equation 13.76). Thus, the [2+2] reaction requires a 16-electron intermediate to bind the olefin or alkyne, even though the metallacyHc product and the imido complex have the same overall electron count. In support of the coordination of alkyne or alkene, albeit weakly, to the d° metal center, the rate of the reaction of alkynes with the 18-electron zirconocene-imido compound containing bound pyridine-N-oxide was inhibited by added pyridine-N-oxide (Equation 13.76). ... 

Intercalation of ruthenium poly(pyridine) complexes into other layered materials has been reported (95-106). The intercalation is not as facile as in smectite systems, which is partly due to the higher charge densities of these host materials. Consequently, quantitative ion exchange of ruthenium complexes with the interlayer cations is difficult. Synthetic efforts have been made to introduce ruthenium polypyridine chelate complexes into magadiite, zirconium phosphate and phos-phonates, LDH, MnPSs, and a transition metal oxide and to control the adsorption states. 

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