Insertion of CS2 into one of the Ir-H bonds of [Ir(H)5(PCy3)2] takes place to afford the dihydrido dithioformate complex cis-[Ir(H)2(eta2-S2CH)(PCy3)2] accompanied by the elimination of H2. Protonation of the dithioformate complex using HBF4.Et2O gives cis-[Ir(H)(eta2-H2)(eta2-S2CH)(PCy3)2][BF4] wherein the H atom undergoes site exchange between the dihydrogen and the hydride ligands. The dynamics was found to be so extremely rapid with respect to the NMR time scale that the barrier to exchange could not be measured. Partial deuteration of the hydride ligands resulted in a J(H,D) of 6.5 and 7.7 Hz for the H2D and the HD2 isotopomers of cis-[Ir(H)(eta2-H2)(eta2-S2CH)(PCy3)2][BF4], respectively. The H-H distance (d(HH)) for this complex has been calculated to be 1.05 A, which can be categorized under the class of elongated dihydrogen complexes. The cis-[Ir(H)(eta2-H2)(eta2-S2CH)(PCy3)2][BF4] complex undergoes substitution of the bound H2 moiety with CH(3)CN and CO resulting in new hydride derivatives, cis-[Ir(H)(L)(eta2-S2CH)(PCy3)2][BF4] (L = CH3CN, CO). Reaction of cis-[Ir(H)2(eta2-S2CH)(PCy3)2] with electrophilic reagents such as MeOTf and Me3SiOTf afforded a new hydride aquo complex cis-[Ir(H)(H2O)(eta2-S2CH)(PCy3)2][OTf] via the elimination of CH4 and Me3SiH, respectively, followed by the binding of a water molecule (present in trace quantities in the solvent) to the iridium center. The X-ray crystal structures of cis-[Ir(H)2(eta2-S2CH)(PCy3)2] and cis-[Ir(H)(H2O)(eta2-S2CH)(PCy3)2][OTf] have been determined.

N] have been prepared by the protonation reaction of the precursor hydrides, trans-[(dppe) 2 Ru(H)(RCN)][BF 4 ] using HBF 4 ·OEt 2 .The variable temperature spin-lattice relaxation times (T 1 , ms) and the H, D coupling constants of the η 2 -HD isotopo- [a]

New dicationic dihydrogen complexes of the type trans‐[M(η2‐H2)(PF3)(diphosphane)2]2+ [M = Ru, diphosphane = dppm (Ph2PCH2PPh2); M = Fe, Ru, diphosphane = dppe (Ph2PCH2CH2PPh2)] have been prepared from the precursor hydrides trans‐[M(H)(PF3)(diphosphane)2]+ upon reaction with HOTf. In the case of dppm, in addition to the trans‐dihydrogen complex cis‐[Ru(η2‐H2)(PF3)(dppm)2]2+ was also obtained in the protonation reaction. The intact nature of the H−H bond in these derivatives has been established using the spin−lattice relaxation time measurements (short T1 values) and the large JH,D coupling constant of the H−D isotopomers. The H−H bond lengths and the stabilities of the dihydrogen complexes are discussed in terms of the π‐acidity of the PF3 ligand and compared with other systems possessing trans CO and CNH ligands. The trans‐[Ru(η2‐H2)(PF3)(dppe)2]2+ complex was found to be remarkably stable with respect to the loss of bound H2 for a period of about 16 h. The H−D isotopomer of this complex exhibits small temperature variations in the JH,D coupling constant. The X‐ray crystal structure of trans‐[Ru(H)(PF3)(dppm)2][BF4] has been determined. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)