Reactions of [ReO X 3 (PPh 3 ) 2 ] Complexes ( X = Cl, Br) with Phenylacetylene and the Structures of the Products

Oxorhenium(V) complexes [ReO X 3 (PPh 3 ) 2 ] ( X = Cl, Br) react with phenylacetylene under formation of complexes with ylide‐type ligands. Compounds of the compositions [ReOCl 3 (PPh 3 ){C(Ph)C(H)(PPh 3 )}] ( 1 ), [ReOBr 3 (OPPh 3 ){C(Ph)C(H)(PPh 3 )}] ( 2 ), and [ReOBr 3 (OPPh 3 ){C(H)C(Ph)(PPh 3 )}] ( 3 ) were isolated and characterized by X‐ray diffraction. They contain a ligand, which was formed by a nucleophilic attack of released PPh 3 at coordinated phenylacetylene. The structures of the products show that there is no preferable position for this attack. Cleavage of the Re–C bond in 3 and dimerization of the organic ligand resulted in the formation of the [{(PPh 3 )(H)CC(Ph)} 2 ] 2+ cation, which crystallized as its [(ReOBr 4 )(OReO 3 )] 2– salt.