THE BINDING OF SMALL NITROGEN-CONTAINING HETEROCYCLES TO NEUTRAL AND CATIONIC (PENTAMETHYLCYCLOPENTADIENYL) IR(III) COMPLEXES AND THE X-RAY CRYSTAL-STRUCTURE OF AN UNEXPECTED DIAQUO COMPLEX, [(CP(ASTERISK))IRCL(H2O)(2)][PF6]

Cleavage of the chloro-bridged [Cp*IrCl2](2) dimer by halide abstraction using [NH4][PF6] leads to the formation of the [Cp*IrCl](+) cation which reacts with 2-picoline, 2,6-lutidine, and 2-methylquinoline to form stable N-bound complexes of the type [Cp*Ir(L)(2)Cl](+). Halide abstraction using AgBF4 results in complete removal of all halides from the dimer to produce the [(Cp*)Ir](2+) dication. Both N and pi-bound complexes can be obtained, depending on the nature of the nitrogen-containing heterocycle. Direct reaction of the [(Cp*)IrCl2](2) dimer with 2,6-lutidine results in cleavage of the dimer to form a Cp*Ir(L)Cl-2 complex containing one N-bound 2,6-lutidine ligand. An iridium complex having the formula [(Cp*)IrCl(H2O)(2)][PF6] was obtained fortuitously during the course of attempts to grow crystals of the cationic 2-picoline complex. The presence of two molecules of water in the coordination sphere of the Ir(III) ion was verified crystallographically. The complex crystallizes in the orthorhombic Pnma space group with a = 20.260(7) Angstrom, b = 8.700(2) Angstrom, c = 9.656(3) Angstrom and V = 1702.0(9) Angstrom(3). Convergence to conventional R values of R = 0.0417 and R(W) = 0.0560 with a goodness-of-fit of 0.72 was obtained for 110 variable parameters and 1205 reflections with I > 0 sigma(I).