Hydrido platinum metal macrocyclic complexes: the synthesis and single-crystal X-ray structure of cis-[IrCl(H)L1]PF6{L1=7-methyl-3,7,11,17-tetrazabicyclo[11.3.1]heptadeca-1(17),13,15-triene}

Abstract

Reaction of IrCl₃·3H₂O with one equivalent of 7-methyl-3,7,11,17-tetra-azabicyclo[11.3.1]heptadeca-1(17),13,15-triene (L¹) in refluxing aqueous EtOH for 72 h affords the hydridoiridium(III) complex [IrCl(H)L¹]PF₆. This crystallises in the monoclinic space group P2₁/c, with a= 10.028(4), b= 11.926(6), c= 16.539(9)Å, β= 99.23(4)°, and Z= 4. A single-crystal X-ray structure shows octahedral Ir^III bound to the folded pyridine-2,6-diyl macrocycle L¹[Ir–N(3) 2.080(11), Ir–N(11) 2.083(11), and Ir–N(17) 1.952(10)Å] with the fourth N donor, N(7), bent away to bind at an axial position [Ir–N(7) 2.266(11)Å]. The Ir atom lies 0.09 Å out of the triaza plane defined by N(3), N(11), and N(17). Chloro and hydrido ligands complete the octahedral co-ordination around the metal centre. The former [Ir–Cl 2.393(4)Å] lies trans to the pyridyl N(17) donor, with the latter trans to N(7);N(17)IrCl 175.7(3), HlrN(7) 172(5)°. The mechanism of formation of the complex, and the role of hydrido species as intermediates in the insertion of platinum metal ions into macrocyclic ligands, are discussed.