Hydrido-clusters derived by protonation, hydrogenation, or photolytic decarbonylation of the chelating diphosphine compounds 1,1-[Os3(CO)10(diphosphine)] where diphosphine is Ph2PCH2CH2PPh2 or Ph2PCH2CH2CH2PPh2, and crystal structure of [OsH2{Ph2P(CH2)3PC6H4}(CO)8]·0.5CH2Cl2
Abstract
The hydrides 1,1-[Os3H(CO)10(diphosphine)]+ were formed by the addition of trifluoroacetic acid to the chelating diphosphine compounds 1,1-[Os3(CO)10(diphosphine)], where diphosphine = Ph2PCH2CH2PPh2(dppe) or Ph2PCH2CH2CH2PPh2(dppp) and were isolated as hexafluorophosphate salts. Reactions of the parent diphosphine compounds with H2 at atmospheric pressure in refluxing toluene do not lead to the simple dihydrides [Os3H2(CO)8(diphosphine)] as found for the corresponding 1,2 isomers. Instead the clusters [Os3H2{Ph2P(CH2)nPC6H4}(CO)8](n= 2 or 3) are obtained by loss of C6H6 and orthometallation. The X-ray structure when n= 3 establishes the presence of the six-electron donating ligand µ3-Ph2PCH2CH2CH2PC6H4. Orthometallation of the clusters 1,1-[Os3(CO)10(diphosphine)] occurs on u.v. photolysis to give [Os3H{Ph2P(CH2)nPPhC6H4}(CO)9](n= 2 or 3) which can be hydrogenated to give the clusters [Os3H2{Ph2P(CH2)nPC6H4}(CO)8]. This is evidence that decarbonylation and orthometallation could occur before hydrogenation in the initial thermal reaction of the diphosphine compounds with H2.