Nucleophilic Addition Reactions of the Osmium−Antimony Cluster (μ-H)Os₃(CO)₉(μ₃-C₆H₄)(μ-SbPh₂): Orthometalation of Triphenylphosphine at Ambient Temperature

At ambient temperatures, the reaction of Os3(μ-H)(μ-SbPh2)(μ3,η2-C6H4)(CO)9, 1, with PPh3 proceeded via a nucleophilic addition product, Os3(μ-H)(μ-SbPh2)(μ2,η2-C6H4)(CO)9(PPh3), 2a. This can lose CO to give Os3(μ-H)(μ-SbPh2)(μ3,η2-C6H4)(CO)8(PPh3), 3a, isomerize, deorthometalate to Os3(μ-SbPh2)(C6H5)(CO)9(PPh3), 5a, or react with excess PPh3 to give an orthometalated product, Os3(μ-SbPh2)(CO)8(PPh2C6H4)(PPh3)2, 6a. The origin of the orthometalated phenyl ring in 6a has been established via the reaction of a p-tolyl analogue of 2a, viz., Os3(μ-H)(μ-SbPh2)(μ2,η2-C6H4)(CO)9{(p-tolyl)3P}, 2b, with PPh3.