Preparation of Cyclopentadienyl Bisphosphine Ruthenium Complexes

In 1971, a preparation of 1 from 2 using thallium cyclopentadienide was reported (I) but the toxicity of thallium and the mass of the reagent needed render this procedure unsuitable for large-scale preparations. An improved method was reported by Bruce et al. (3,4), using cyclopentadiene, ruthenium trichloride hydrate (3), and triphenylphosphine, which gives the desired complex in high yield [Eq. (2)]. The primary advantage of this latter method is formation of the complex in one pot. 

An interesting synthesis of the cyclopentadienyl bisphosphine ruthenium nitrosyl complex 9 involves the thermal displacement of both phenyl groups from (i75-C5H5)Ru(NC))PIi2 (8) with a chelating diphosphine [Eq. (6)] (72). Infrared data indicate that the nitrosyl ligand is linear (3 e  

TABLEi Bond Angles in ( -C5H5)(PMe3)2RuCl] (11)  

Sterically bulky chelating diphosphines such as (/ )-Ph2PCHMeCH2PPh2 [(/ )-PROPHOS] form ruthenium complexes with P—Ru—P bond angles considerably smaller than those exhibited for the analogous triphenyl-phosphine complexes, often less than the idealized 90°. This is a consequence of constraints on the bite angle of the two phosphorus atoms 

TABLE II Bond Angles in [(T)5-C5H5)(PPhj)2RuCI] (1)  

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