Poly borate complexes, group

Properties of nickel poly(pyrazol-l-yl)borate complexes such as solubility, coordination geometry, etc., can be controlled by appropriate substituent groups on the pyrazol rings, in particular in the 3- and 5-positions. Typical complexes are those of octahedral C symmetry (192)°02-604 and tetrahedral species (193). In the former case, two different tris(pyrazolyl)borate ligands may be involved to give heteroleptic compounds.602,603 Substituents in the 5-position mainly provide protection of the BH group. Only few representative examples are discussed here. 

The Organometallic Chemistry of Group 10 Poly(pyrazolyl) borate Complexes... 

It is perhaps unsurprising that the role of phosphane ligands in group 10 poly(pyrazolyl)borate complexes can often be summarized as "spectator-ial," and in many instances is incidental in respect of chemistry. Indeed, the dominant utility of these ligands is as donors with which to trap or stabilize coordinately unsaturated materials. 

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