Synthesis, structure and reactivity of triosmium clusters derived from the reactions of [Os3(CO)10(µ-dppm)] (dppm = Ph2PCH2PPh2) and [Os3(µ-H)(CO)8{Ph2PCH2P(Ph)C6H4}] with PHPh2

Abstract

The reaction of [Os₃(CO)₁₀(µ-dppm)] 1 with diphenylphosphine in refluxing toluene led to the substituted cluster [Os₃(CO)₉(µ-dppm)(PHPh₂)] 3 and the phosphido-bridged dihydride [Os₃H(µ-H)(CO)₇(µ-dppm)(µ-PPh₂)₂] 4. The cluster 4 exists as three isomeric forms in solution. The 46-electron compound [Os₃(µ-H)(CO)₈{Ph₂PCH₂P(Ph)C₆H₄}] 2 reacted with an excess of PHPh₂ at room temperature to yield [Os₃(µ-H)(CO)₈{Ph₂PCH₂P(Ph)C₆H₄}(PHPh₂)] 5 and [Os₃(CO)₈(µ-dppm)(PHPh₂)₂] 6 in 16 and 62% yields respectively. Thermolysis of 6 in refluxing toluene gave 4 and two stereoisomeric compounds 7 and 8 with stoichiometry [Os₃(µ-H)₂(CO)₆(µ-dppm)(µ-PPh₂)₂]. The cluster 3 decarbonylated at 110 °C to give the phosphido-bridged monohydride cluster [Os₃(µ-H)(CO)₈(µ-dppm)(µ-PPh₂)] 9 which exists as two isomers in solution. Compound 4 converts into 7 and 8 on thermolysis in toluene. All the compounds have been characterized by infrared, ¹H and ³¹P-{¹H} NMR spectroscopy and elemental analysis and in the case of 3, 4, 6 and 7 also by X-ray crystallography.