Reactivity of 2?mercaptopyridines with Iridium(I)?Tris(pyrazolyl) borate complexes

Reaction of of the Ir(I) complex [TpMe2Ir?(C2H4)2] (1) with a variety of mercaptopyridines produces in good yields the Ir(III)?metallacycles 2?4 with the general formula [TpMe2Ir(C2H5)(k2?(N,S)?mercaptopyridine)]. Complexes 2?4 are proposed to take place by the initial formation of the 16 electron intermediate [TpMe2Ir(CH=CH2)(C2H5)] which then coordinates the nitrogen atom of the mercaptopyridine and promotes the deprotonation of the SH group via the elimination of an ethylene molecule. Heating of complex [TpMe2Ir(?4?CH2=C(Me)C(Me)=CH2)] (5) at 100?C with the substituted mercaptopyridines results in the formation of the Ir(III) complexes 6?8 with the general formula [TpMe2Ir(C6H5)(?2?(N,S)?mercaptopyridine)]. Generation of complexes 6?8 is proposed to take place by the initial formation of the [TpMe2Ir(C6H5)2N2] complex which after releasing nitrogen coordinates the mercaptopyridine in a ?1?fashion and favour the SH moiety deprotonation with the release of a benzene molecule. All complexes have been fully characterized by NMR spectroscopy, FT?IR, elemental analysis and in the case of 2, 4, and 8 by X?ray crystallography. Details of the reaction conditions, characterization and isolation of the products will be discussed.