Synthesis and reactivities of a bis(cyanamido)-capped triruthenium complex

The tetraruthenium complex Cp*RuCl]4 (Cp* = eta(5)-C(5)Me(5)) reacts with Na(2)NCN to afford the anionic bis(cyanamido)-capped triruthenium complex (Cp*Ru)3(micro(3)-NCN)(2)]- ((2-)), which undergoes single electron oxidation to form (Cp*Ru)3(micro(3)-NCN)2] upon workup with 1 equiv. of Cp(2)Fe](PF(6)) (Cp = eta(5)-C(5)H(5)). Treatment of (2-) with 1 equiv. of HCl at room temperature leads to the protonation of one of the Ru-Ru edges to give the hydrido-bridged complex (Cp*Ru)3(micro-H)(micro-NCN)2], while the cationic side-on NCNH(2) complex (Cp*Ru)3(micro-Cl)(micro(3)-NCN)(micro(3)-NCNH(2)-1kappaC,N:2kappaC:3kappaN)]Cl (5) is obtained by the reaction of (2-) with an excess amount of HCl at -78 degrees C. On the other hand, the reaction of (2-) with BR(3) (R = Et, Ph) results in the ligation of two BR(3) molecules to the terminal nitrogen atoms of the cyanamido ligands to yield the bis(borane) adduct (PPN)(Cp*Ru)(3){(micro(4)-NCN)(BR(3))}(2)] (6, PPN = Ph(3)PNPPPh(3)). 6b (R = Et) slowly liberates one BEt(3) molecule in acetone to give the mono(borane) adduct (PPN)(Cp*Ru)3(micro(3)-NCN){(micro(4)-NCN)(BEt(3))}] (7). (2-) is also shown to react with AuCl(PPh(3))] or PhCOCl to afford the tetranuclear heterometallic complex (Cp*Ru)3(micro(3)-NCN){(micro(4)-NCN)(AuPPh(3))}] (8) or the benzoylcyanamido complex (Cp*Ru)3(micro(3)-NCN)(micro(3)-NCNCOPh)] in which the Au(PPh(3))+ or benzoyl fragment is bound to the terminal nitrogen atom of a cyanamido ligand. The molecular structures of PPN+(2-), 5.C(6)H(6), 7 and 8.C(6)H(6) have been determined by single-crystal X-ray analyses.