Reaction of H 2Ru 2(CO) 5( iPr-DAB{H,R}) (RH ( 1a); RMe ( 1b)), which contains one terminal and one bridging hydride, with CX 4 (XCl; XI) afforded HRu 2(X)(CO) 5( iPr-DAB{H,R}) (XCl, RH ( 3a); X= CI, R=Me ( 3b); XI, RH ( 3c)). As confirmed by a single crystal X-ray structure determination, complex 3a contains a bimetallic unit bridged by a hydride and a 6e σ-N,μ2-N′,η 2-CN′ bonded DAB ligand, whereas the chloride is terminally bonded. Crystals of 3a are monoclinic, space group P2 1/ c, a = 12.421(2), b = 12.003(2), c= 13.227(1) Å, β = 90.22(1)°, Z = 4. The structure was refined to R = 0.043 for 2947 observed reflections. Reaction of 3a with D 2 at 70 °C afforded DRu 2(Cl)(CO) 5( iPr-DAB) ( 3a′), whereas 3a′ could be reconverted to 3a by reaction with H 2. To rationalize these results it is suggested that in the first step of the reaction, e.g. of 3a with D 2, the D 2 molecule attacks the empty position created by rupture of the Ru-η 2-CN′ bond. Exchange of H by D may occur via an intermediate containing a HD 2 species coordinated to the bimetallic moiety. Raising the reaction temperature to 90 °C leads subsequently to the reduction of the coordinated DAB ligand, whereby 3a and 3c are converted to HRu 2(X)(CO) 5( iPr-N-CH 2 CH 2-N- ipr)(XCl ( 4a); XI ( 4c), together with small amounts of the side product Ru 2(CO) 6 ( iPr-N-CH 2CH 2-N- 1Pr) ( 5a). The latter was formed from 4a, as established by refluxing complexes 4 in toluene which yielded 5a. However, in contrast to 3a and 3c, reaction of 3b with hydrogen at 90 °C afforded only Ru 2(CO) 6( iPr-N-C(H)(Me)CH 2-N- ipr) ( 5b). Complexes 4 could also be prepared by reacting H 2Ru 2(CO) 5( iPr-N-CH 2CH 2-N- ipr) ( 2a) with CX 4. Interestingly, for example, reaction of DRu 2(Cl)(CO) 5( iPr- DAB{H,R}) with D 2 at 90 °C showed in the final product the presence of D at all sites of the reduced central CC bond of R-DAB with an average varying between 0.5 and 1 proton on this moiety, indicating the occurrence of intramolecular CH/CD bond making and bond breaking steps during the hydrogenation process. Reaction of 3a with AgOTF yielded [OTF][HRu 2(CO) 5( iPr-DAB)] ( 6), which subsequently could be converted to [OTF][HRu 2(CO) 5(L)( iPr-DAB)] (LCO ( 8); L=′Bu-NC ( 9)) and to [HRu 2(X)(CO) 5( iPr-DAB)] (XCo(CO) 4 ( 3d); XMn(CO) 5 ( 3e); XCN ( 3f)). Whereas the DAB ligand of 6 could be reduced, complexes 3d-f, 8 and 9 could not be hydrogenated.