SYNTHESIS AND REACTIVITY OF THE FORMALLY COORDINATIVELY UNSATURATED DIRUTHENIUM HYDRIDE P(OPRI)(2))(2)](-(PRIO)(2)PNETP(OPRI)(2))(2)](+)() AND ITS COORDINATIVELY SATURATED PARENT [RU2H(CO)(5)(MU)

Protonation of the co-ordinatively unsaturated species [Ru-2(mu(sb)-CO )(2)(CO)(2)(mu-etipdp)(2)] [sb = semi-bridging, etipdp = ((PrO)-O-t)(2 )PNEtP(OPrt)(2)] by acids of non-co-ordinating conjugate bases, e.g; H BF4 . OEt(2), produced [R(u)(mu-H>(mu-Co)(Co)(3)(mu-etipdp)(2)](+) whi ch, as established X-ray crystallographically for the PF6- salt, conta ins both a bridging carbonyl and a bridging hydride ligand. This catio nic species is very susceptible to attack by both neutral and anionic nucleophiles affording a range of product types. For instance, its rea ctions with anions X(-) which are capable of functioning as monodentat e bridging ligands and which preferentially adopt the closed bridging co-ordination mode, e.g. halide and hydrogensulfide ions, afforded pro ducts of the type [Ru-2(mu-X)H(mu(sb)-CO)(CO)(2)(mu-etipdp)(2)] (X = C l, Pr, I, SH, etc.), resulting from the substitution of a carbonyl gro up by the nucleophile. On the other hand, anionic nucleophiles such as H- and CN- gave addition products of the type [Ru(2)HX(CO)(4)(mu-etip dp)(2)] (X = H, CN, etc;) in which the hydride and the X(-) ligand occ upy equatorial sites trans disposed with respect to each other, as est ablished in a separate study for [Ru2H2(CO)(4)(mu-etipdp)(2)]. Carbon monoxide also afforded a simple addition product, viz. [Ru2H(CO)(5)(mu -etipdp)(2)](+), but the majority of the other neutral nucleophiles st udied, particularly the unsaturated systems, yielded products resultin g from formal insertion of the nucleophile into the Ru-H bond, Thus su lfur produced [Ru-2(mu-SH)(CO)(4)(mu-etipdp)(2)](+) while unsaturated nucleophiles of general formula X'=Y', e.g. PhC=N and RC=CH (R = H, Ph , etc.), gave products of the type [Ru-2{mu-X'Y'(H)}(CO)(4)(mu-etipdp) (2)](+), e.g. [Ru-2{mu-NC(H)Ph}(CO)(4)(mu-etipdp)(2)](+) + or of the t ype [Ru-2{mu-eta(2)-X'Y'(H)}(CO)(4)(mu-etipdp)(2)](+), e.g. (mu-eta(1) :eta(2)-CHCHR)(CO)(4)(mu-etipdp)(2)](+). Heterocumulenes X '' Y '' Z ' ' such as CS2 and PhNCS behaved similarly affording products of genera l formula [Ru-2{mu-eta(2)-X '' Y ''(H)Z ''}(CO)(4)(mu-etipdp)(2)](+) c ontaining five-membered RuX '' Y '' Z '' Ru rings. The co-ordinatively saturated pentacarbonyl [Ru2H(CO)(5)(mu-etipdp)(2)]PF6 gave products similar to those afforded by [Ru-2(mu-H)(mu-CO)(CO)(3)(mu-etipdp)(2)]P F6 on reaction with systems of the type X'=Y' and X '' Y '' Z '' excep t that, for terminal alkynes such as PhC=CH, alkenylcarbonyl-bridged p roducts, e.g. 2(mu-eta(2)-OC(CH=CHPh>)(CO)(4)(mu-etipdp)(2)]PF6, are p roduced. The crystal structures of the following compounds were determ ined: [Ru-2(mu-H)(mu-CO)(CO)(3)(mu-etipdp)(2)]PF6, [Ru-2(mu-I)H(mu(sb) -CO)(CO)(2)(mu-etipdp)(2)], [Ru-2{mu-N(CHPh)}(CO)(4)(mu-etipdp)(2)]PF6 , (mu-eta(1):eta(2)-CHCH2)(Co)(4)(mu-etipdp)(2)]PF6, u-2{mu-eta(2)-OC( CHCHPh)}(Co)(4)(mu-etipdp)(2)]PF6 and Ru-2{mu-eta(2)-SC(H)NPh}(CO)(4)( mu-etipdp)(2)]PF6.