Transition Metal Chemistry of a Novel and Versatile Heterodifunctional Phosphorus-Nitrogen Ligand System

Abstract

There is considerable current interest in the chemistry of transition metal complexes containing ligands with distinctly different heteroatomic donor atoms because of the key role that such systems are likely to play in the development of useful catalysts for specific chemical transformations.¹ Use of heterodifunctional ligands: R₂P₆H₄-CO₂ ^-2, R₂P-C₆H₄-SO₃ ^-3 R₂P-CH˭C(R)OH⁴ and R₂P-CH₂) _n -P(O)R₂ ¹⁰ or functionalized substituents such as O-CH₂PR₂ ^Ih are but a few examples of a laree class of heterodifunctional phosphines, the metal complexes of which have found important industrial applications as useful homogeneous catalysts and catalyst precursors. Despite the importance of heterofunctional phosphine ligands in general. efforts to develop the chemistry of this class of main group systems and also to develop directed synthetic strategies which can be applied to the synthesis of a series of ligands in which the structure and suhstituents may be varied to “tune” the reactivity of one or more of the heteroatoms has been spotty. A unified and systematic approach to the synthesis of carefully designed heterodifunctional ligands would therefore present considerable opportunities for the formation of a variety of metal complexes with useful chemical and stereochemical catalytic properties. Herein we describe our development of a novel and unified approach to the synthesis of heterodifunctional phosphines (and arsines) and the new transition metal organometallic and coordination chemistry that has emerged from the use of this lizand system.

Key Words:

• ligands
• heterobifunctional
• phosphorus nitrogen
• imine
• phosphine
• transition metal
• chelate
• bimetallic