Synthesis, Molecular Structure, and CC Coupling Reactions of Carbeneruthenium(II) Complexes with C₅H₅Ru(CRR′) and C₅Me₅Ru(CRR′) as Molecular Units

Abstract

The ethene derivatives [(eta(5)-C(5)R(5))RuX(C(2)H(4))(PPh(3))] with R=H and Me, which have been prepared from the eta(3)-allylic compounds [(eta(5)-C(5)R(5))Ru(eta(3)-2-MeC(3)H(4))(PPh(3))] (1, 2) and acids HX under an ethene atmosphere, are excellent starting materials for the synthesis of a series of new halfsandwich-type ruthenium(II) complexes. The olefinic ligand is replaced not only by CO and pyridine, but also by internal and terminal alkynes to give (for X=Cl) alkyne, vinylidene, and allene compounds of the general composition [(eta(5)-C(5)R(5))RuCl(L)(PPh(3))] with L=C(2)(CO(2)Me)(2), Me(3)SiC(2)CO(2)Et, C=CHCO(2)R, and C(3)H(4). The allenylidene complex [(eta(5)-C(5)H(5))RuCl(=C=C=CPh(2))(PPh(3))] is directly accessible from 1 (R=H) in two steps with the propargylic alcohol HC triple bond CC(OH)Ph(2) as the precursor. The reactions of the ethene derivatives [(eta(5)-C(5)H(5))RuX(C(2)H(4))(PPh(3))] (X=Cl, CF(3)CO(2)) with diazo compounds RR'CN(2) yield the corresponding carbene complexes [(eta(5)-C(5)R(5))RuX(=CRR')(PPh(3))], while with ethyl diazoacetate (for X=Cl) the diethyl maleate compound [(eta(5)-C(5)H(5))RuCl[eta(2)-Z-C(2)H(2)(CO(2)Et)(2)](PPh(3))] is obtained. Halfsandwich-type ruthenium(II) complexes [(eta(5)-C(5)R(5))RuCl(=CHR')(PPh(3))] with secondary carbenes as ligands, as well as cationic species [(eta(5)-C(5)H(5))Ru(=CPh(2))(L)(PPh(3))]X with L=CO and CNtBu and X=AlCl(4) and PF(6), have also been prepared. The neutral compounds [(eta(5)-C(5)H(5))RuCl(=CRR')(PPh(3))] react with phenyllithium, methyllithium, and the vinyl Grignard reagent CH(2)=CHMgBr by displacement of the chloride and subsequent C-C coupling to generate halfsandwich-type ruthenium(II) complexes with eta(3)-benzyl, eta(3)-allyl, and substituted olefins as ligands. Protolytic cleavage of the metal-allylic bond in [(eta(5)-C(5)H(5))Ru(eta(3)-CH(2)CHCR(2))(PPh(3))] with acetic acid affords the corresponding olefins R(2)C=CHCH(3). The by-product of this process is the acetato derivative [(eta(5)-C(5)H(5))Ru(kappa(2)-O(2)CCH(3))(PPh(3))], which can be reconverted to the carbene complexes [(eta(5)-C(5)H(5))RuCl(=CR(2))(PPh(3))] in a one-pot reaction with R(2)CN(2) and Et(3)NHCl.

Ruthenium vs. Osmium Complexes as Catalysts for Atom Transfer Radical Addition Reactions

“…[8] A likely candidate for the active Ru II catalyst is the 16e -complex [Cp*RuCl(PPh 3 )], but attempts to prepare this complex on a preparative scale have failed. [9] However, it was possible to stabilize a structurally related complex by using a sterically very demanding cyclopentadienyl ligand. [10] In the case of Os, the synthesis and the structure of the 16e -complex [Cp*OsBr(PiPr 3 )] has been reported, [11] but, to the best of our knowledge, an analogous PPh 3 complex is not known.…”

Atom‐Transfer Radical Addition Reactions Catalyzed by RuCp* Complexes: A Mechanistic Study

“…It should be noted that previous attempts to make complex 3 on a preparative scale have failed. [12] However, a structurally related complex with a sterically demanding cyclopentadienyl ligand has recently been characterized crystallographically. [13] For reactions with the catalyst precursor 2, the active intermediate 3 can be accessed by loss of one phosphine ligand.…”

Organometallic Chemistry of Ga+: Formation of an Unusual Gallium Dimer in the Coordination Sphere of Ruthenium

“…The methylallyl ligand is characterized by a typical h 3 coordination mode with CÀC and Ru À C bond lengths similar to those of reported ruthenium allyl complexes. [32][33][34][35][36][37] In analogy to the addition of H + , we treated of 1 with one molar equivalent of the Ga + transfer reagent [Ga 2 Cp*]-…”