Synthesis and characterization of dinuclear complexes : 1. dirhodium complexes; 2. platinum-rhodium complexes

PART I

Binuclear rhodiiiin(I) complexes containing terminal carbon monoxide (or terminal tertiarybutylisocyanide), bridging (diphenylarsino)- (diphenylphosphino)methane ligands, and a pyrazolate (pyz) derivative in the bridgehead position have been investigated. Air-stable, paramagnetic products of some of the t-butylisocyanide containing species have been prepared via electrochemical oxidation.

In solution these paramagnetic species exhibit a color change from green to red upon cooling to below room temperatures. Also, the ESR spectrum of [Rh₂(t-BuNC)₂(μ-dapm)₂(μ-345Bpyz)][PF₆]₂ in 4:1 methylene chloride/toluene solution at various temperatures (25°C to –150°C) revealed the existence of two isomers, an α isomer and a β isomer. The relative amounts of these isomers present varied with the temperature.

PART II

Novel heterobimetallic platinum(II)-rhodium(I) complexes employing either bis(diphenylphosphino)methane or (diphenylarsino)(diphenylphosphino)methane as the bridging transoid ligands and containing either a terminal carbon monoxide or a terminal t-butylisocyanide at the rhodium(I) atom, and containing either a cyano or a phenylacetylide ligand at the platinum(II) atom with a pyrazolate (pyz) derivative in the bridgehead position have been synthesized and characterized.

The novel heterobimetallic complex [cis-C1Pt(P:P') (μ-35dmpyz) (μdapm)₂-trans-Rh(As:As')(CO)]PF₆ has been synthesized and characterized. Refluxing a chloroform solution of this complex for several hours revealed the formation of a new compound which was formulated as [trans-C1Pt(P:P')(μ-35dmpyz)(&,u;-dapm)₂-trans-Rh(As:As')(CO)]PF₆. Thus, isomerization of the cis-P-Pt-P unit to a trans-P-Pt-P unit in this complex has been demonstrated.