Reactivity of diynes with a 1-azavinylidene-bridged triruthenium carbonyl cluster. Insertion reactions of diynes into Ru-H, Ru-C, and Ru-N bonds

The reactivity of the 1-azavinylidene cluster complex [Ru-3(mu -H)(mu -N=CPh2)(CO)(10)] (1) with diynes has been studied. The nonconjugated diyne l-trimethylsilyl-l,4-pentadiyne affords the binuclear ynenyl derivative [Ru-2(mu -N=CPh2)(mu-eta (CH2)-C-2=CCH2C=CSiMe3)(CO)(6)] (2), which results from cluster fragmentation and from the insertion of the terminal alkyne fragment of the diyne into a Ru-H bond. The reactions of 1 with the internal conjugated diynes 1,6-diphenoxy-2,4-hexadiyne; 2,4-hexadiyne, and diphenylbutadiyne have allowed the isolation of the trinuclear derivatives [Ru-3{mu-eta (2)-N=CPh(C6H4)}(mu (3)-eta (4)-PhOCH2CH=C=C=CHCH2OPh)- (CO)(8)] (3), [Ru-3{mu (3)-eta (4)-N=CPh(C6H4)CH(Me)CH=C=CMe}(CO)(9)] (4), [Ru-3{mu-eta (2)-N=CPh-(C6H4)}(mu (3)-eta (4)-PhCH=CHC=CPh)(CO)(8)] (5), and [Ru-3{mu (3)-eta (4)-PhCHCH=C(CPh)N=CPh(C6H4)}-(CO)(9)] (6). The four compounds have been characterized by X-ray diffraction methods. They all arise from the orthometalation of a phenyl ring of the 1-azavinylidene ligand and from the transfer of two hydride ligands (the original plus that coming from the orthometalation) to the coordinated diyne. This hydrogenation process can proceed as a 1,4-addition to give a 1,2,3-triene fragment (as occurs in 3) or as a 1,2-addition to give an enyne fragment (as Occurs in 5). In the cases of 4 and 6, a 1,2-addition of hydrogen is accompanied by the insertion Of the unsaturated hydrocarbon fragment into the Ru-C bond associated with;the orthometalated ring (4, 6) and into a Ru-N bond (6). The precise order by which these processes lead to the corresponding products has not been established. The reactions involved in the formation of compounds 2-6 represent excellent examples of insertion of diynes into M-H, M-C, and M-N bonds of metal clusters and have allowed the characterization of substituted 1-yn-3-enyl (in 2), 1,2,3-triene (in 3), 1,2-dienyl (in 4), 1-en-3-yne (in 5), and 2-(N-imido)-1,2,3-allyl-1-yl (in 6) ligands.