Heteroleptic catalytic complexes

Fig. 16.5 Structure of representative heteroleptic catalytic complexes for RCM reaction...

Heteroleptic organolanthanide complexes containing reactive Ln-X bonds and stabilizing ancillary ligands are key precursor compounds in catalytic transformations. Mononuclearity is usually a prerequisite for both good solubility and reactivity. Utilization of bulky ligands, ate complexation, and donor functionalization are applicable procedures for generating mononuclear complexes. 

This review deals with the chemistry and coordination complexes of isoelectronic analogues of common oxo-anions of phosphorus such as PO3, POl", RPOl" and R2POy. The article begins with a discussion of homoleptic systems in which all of the 0x0 ligands are replaced by imido (NR) groups. This is followed by an account of heteroleptic phosphorus-centered anions, including [RN(E)P(/<-NR )2P(E)NR]2-, [EP(NR)3]3-, [RP(E)(NR)2] and [R2P(E)(NR )] (E=0,S, Se, Te). The emphasis is on the wide variety of coordination modes exhibited by these poly-dentate ligands, which have both hard (NR) and soft (S, Se or Te) centers. Possible applications of their metal complexes include new catalytic systems, coordination polymers with unique properties, and novel porous materials. 

Building on this concept, Takacs et al. have reported the construction of a chiral bidentate phosphate ligand by assembly via a heteroleptic complex thus, it was proposed that if a supramolecular polymer could be prepared around a structural metal atom (Ms), then a second metal can be coordinated that acts as the catalytically active site (Meat, Scheme 6). 

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