Edwards, KJ; Field, JS; Haines, RJ; Homann, BD; Stewart, MW; Sundermeyer, J; Woollam, SF
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; HBF4 . OEt(2), produced [R(u)(mu-H>(mu-Co)(Co)(3)(mu-etipdp)(2)](+) which, as established X-ray crystallographically for the PF6- salt, contains both a bridging carbonyl and a bridging hydride ligand. This cationic species is very susceptible to attack by both neutral and anionic nucleophiles affording a range of product types. For instance, its reactions with anions X(-) which are capable of functioning as monodentate bridging ligands and which preferentially adopt the closed bridging co-ordination mode, e.g. halide and hydrogensulfide ions, afforded products of the type [Ru-2(mu-X)H(mu(sb)-CO)(CO)(2)(mu-etipdp)(2)] (X = Cl, Pr, I, SH, etc.), resulting from the substitution of a carbonyl group 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-etipdp)(2)] (X = H, CN, etc;) in which the hydride and the X(-) ligand occupy equatorial sites trans disposed with respect to each other, as established 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 studied, particularly the unsaturated systems, yielded products resulting from formal insertion of the nucleophile into the Ru-H bond, Thus sulfur 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 type [Ru-2{mu-eta(2)-X'Y'(H)}(CO)(4)(mu-etipdp)(2)](+), e.g. [Ru-2(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 general formula [Ru-2{mu-eta(2)-X '' Y ''(H)Z ''}(CO)(4)(mu-etipdp)(2)](+) containing 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)]PF6 on reaction with systems of the type X'=Y' and X '' Y '' Z '' except that, for terminal alkynes such as PhC=CH, alkenylcarbonyl-bridged products, e.g. [Ru-2(mu-eta(2)-OC(CH=CHPh>)(CO)(4)(mu-etipdp)(2)]PF6, are produced.
The crystal structures of the following compounds were determined: [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, [Ru-2(mu-eta(1):eta(2)-CHCH2)(Co)(4)(mu-etipdp)(2)]PF6, [Ru-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.