“…[10] Therefore, this base-promoted splitting of dihydrogen through formation of a (ligandϪH ϩ )Ϫ(metalϪH Ϫ ) intermediate is of great significance with regard to catalytic ionic hydrogenations, as recently described by Noyori. [11,12] In order to design such a bifunctional system, we set out to prepare a series of cationic nitrosyltungsten and nitrosyltungsten hydride species having basic pyridyl substituents present in their coordinatrans-HW(CO) 2 (NO)(Ph 2 Ppy) 2 (10), trans,trans-HW(CO) 2 (N-O)(Ph 2 Ppic) 2 (12), trans,trans-HW(CO) 2 (NO)(Ph 2 -tBupy) 2 (15), cis/trans-HW(CO) 2 (NO)(Me 2 Ppy) 2 (17), and cis/trans-HW(CO) 2 (NO)(Me 2 P-tert-Bupy) 2 (19), respectively. Reactivity experiments with acetic acid, hydroiodic acid, carbon dioxide, and acetylenedicarboxylic acid were performed, and were found to afford trans-W(CO)(NO)(Ph 2 Ppy) 2 (η 2 -CH 3 CO 2 ) (24), trans,trans-IW(CO) 2 (NO)(Ph 2 Ppy) 2 (25), trans-W(HCO 2 )(CO) 2 (NO)(Ph 2 Ppy) 2 (26), and trans-W{η 2 -(Z)-C(CO 2 Me)=CH[C(O)OMe]}(CO)(NO)(Ph 2 Ppic) 2 (27), respectively.…”