Competition between NH center dot center dot center dot HIr intramolecular proton-hydride interactions and NH center dot center dot center dot FBF3- or NH center dot center dot center dot O intermolecular hydrogen bonds involving [IrH(2-thiazolidinethione)(4)(PCy(3))](BF4)(2) and related complexes

The reaction of IrH5(PCy(3))(2) in acetone with 2 equiv of HBF4 results in the formation of the air-stable complex [Ir(H)(2)(PCy(3))(2)(acetone)(2)]BF4, 1. The reaction of 1 with an excess of 2-thiazolidinethione or 2-benzothiazolethione in the presence of 2 equiv of HBF4 gives the complexes [Ir(H)(PCy(3))(L)(4)](BF4)(2) (2a, L = 2-thiazolidinethione; 2b, L = 2-benzothiazolethione). Complex 2a has an intramolecular NH ... H(Ir)... HN interaction both in the crystalline solid as determined by X-ray diffraction and in a CD2Cl2 solution as determined by the T-1 method. The d(HH) were determined to be 2.2 +/- 0.1 Angstrom in the solid state and 1.9 +/- 0.1 Angstrom in solution. The NH ... H(Ir)... HN interactions and NH ... F ... HN hydrogen bonds which involve FB3- form a four-member ring in a butterfly conformation. The nOe effect of the hydride on the NH proton is around 10%. A crystal of 2a is in the triclinic space group <P(1)over bar> with a = 11.426(3), b = 11.922(3), c = 19.734(4) Angstrom, alpha = 87.05(1)degrees, beta = 88.23(1)degrees, gamma = 75.50(1)degrees, V = 2599(1) Angstrom(3), and Z = 2 at T = 173 K; full-matrix least-squares refinement on F-2 was performed for 10 198 independent reflections; R[F-2>2 sigma(F-2)] = 0.0480, R(w)(F-2) = 0.099. The formation of the NH ... HIr proton-hydride interaction is as favorable as the formation of intermolecular hydrogen bonds NH ... FBF3- or NH ... O hydrogen bonds with OPPh(3) or H2O in CD2Cl2. A similar NH ... HIr interaction also has been observed in the complexes [Ir(H)(2)(PCy(3))(2)(L)(2)]BF4 (3a, L = 2-thiazolidinethione; 3b, L = 2-benzothiazolethione) but not in the complexes with L = NH2NH2 (3c) and L = NH3 (3d). Both the NH and IrH protons are deuterated when a solution of 2 or 3 in C6D6 is exposed to 1 atm of D-2 gas or D2O.