The facile reaction of water with a bimetallic nickel tetrachloride tetraphosphine: A tale of two chelates

The bis(phosphino)ethane chelate demonstrates remarkable coordination weakness in a series of dinickel(II) tetrachloride complexes based on a binucleating racemic- and meso-tetraphosphine ligands. Addition of water to these complexes results in loss of chloride and formation of a hydroxide-bridged dinickel species. This is followed by facile loss of one nickel center at room temperature for the meso-P4 diastereomer forming several monometallic complexes that ultimately dimerize to form a new tricationic dinickel(II) species with a bridging chloride and two coordinated tetraphosphine ligands. This new bimetallic complex is also quite susceptible to fragmentation reactions. Comparisons with a far more strongly chelating P4 ligand are presented.