Tetraphosphine chelates

The chelating tertiary diphosphines 43) and arsines 43, 149) give dicarbonyl compounds easily. Analogous to this is the behavior of the tetraphosphine, C(CH2-PR2)4, which gives the disubstitution compound and forms two chelate rings giving a carbonylated spiro nickel (0) derivative ( ). 

Our work into bimetallic cooperativity in homogeneous catalysis has concentrated on the binucleating tetraphosphine ligands meso- and racemic-et,ph-P4, shown in Scheme 3 [25, 26]. These ligands are designed to chelate two metal centers via a single, conformationally flexible, methylene bridge. 

Scheme 2.25 Multiple chelation modes in rhodium complexes with biaryl tetraphosphines. 2.1.5...

Scheme 12.16). This finding had been ascribed to the steric protection and chelate effect of the tetraphosphine macrocyclic ligand [55]. 

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