Imido complexes Ru

A mono(imido) complex Ru (TBPPXNR) (R = p-XCeH where X = Me, H, Cl, 1) (analogous to Ru (porp)0) has been prepared via reaction... 

A further mthenium(IV) complex, [Ru(ti -TsN—N=N-NTs)(S2CNEt2)2] (270), has been prepared in 35% yield from the reaction of excess tosylazide and ciJ-[Ru(PPh3)2(S2CNEt2)2] (268) (287). The structure is confirmed crystal-lographically and the authors speculate that it results from initial formation of a ruthenium(IV) imido complex, [Ru(NTs)(S2CNEt2)2] (269), which reacts further with a second equivalent of azide (Eq. 123). 

Imidazolium ligands, in Rh complexes, 7, 126 Imidazolium salts iridium binding, 7, 349 in silver(I) carbene synthesis, 2, 206 Imidazol-2-ylidene carbenes, with tungsten carbonyls, 5, 678 (Imidazol-2-ylidene)gold(I) complexes, preparation, 2, 289 Imidazopyridine, in trinuclear Ru and Os clusters, 6, 727 Imidazo[l,2-a]-pyridines, iodo-substituted, in Grignard reagent preparation, 9, 37—38 Imido alkyl complexes, with tantalum, 5, 118—120 Imido-amido half-sandwich compounds, with tantalum, 5,183 /13-Imido clusters, with trinuclear Ru clusters, 6, 733 Imido complexes with bis-Gp Ti, 4, 579 with monoalkyl Ti(IV), 4, 336 with mono-Gp Ti(IV), 4, 419 with Ru half-sandwiches, 6, 519—520 with tantalum, 5, 110 with titanium(IV) dialkyls, 4, 352 with titanocenes, 4, 566 with tungsten... 

No mononuclear imido complexes of Ru(IV) have yet been isolated. The recently reported imido-bridged dimer [Ru(t)-C6H6)(2V-2,6-Pr2 C6H3)]22 has ruthenium in an oxidation state of +11 (98). 

No imido complexes of Ru(VIII) have yet been reported. 

Reaction of [Ru(TPP)(CO)] (TPP = tetraphenylporphyrin) with PhI=NTs generates a Ru(VI) bis-imido complex, which has been crystallographically characterized [62]. This species is chemically competent as an N-centered oxidant, and will react with olefin, benzylic, and adamantyl substrates to form sulfonylaziridine and sulfonamide products, respectively (Fig. 11). The availability of this meta-stable adduct has offered a unique opportunity to study directly the mechanism of the C-H... 

Fig. 11 An isolable Ru(VI) bis-imido complex competent for N-atom transfer...

A fluorinated tetraphenylporphyrm-Ru(II) complex, [Ru(F20-TPP)(CO)], reacts with TcesN=IPh to generate a bis-imido Ru(VI) adduct (eq 7)7 This complex oxidizes benzylic (fluorene, cumene, toluene) and allylic (cyclohexene) hydrocarbons to give the corresponding Tces-amide products. The solid iodoitnine oxidant is prepared from TcesNH2, PhI(OAc)2, and KOH. 

By reaction of Fe3(CO)i2 with aromatic nitro compounds in benzene, derivatives such as 1 and 3 (R = Aryl) have been obtained [59, 60]. Similarly, nitrobenzene reacts with Ruj(CO)i2 in boiling benzene to give the ruthenium homologues of 1 and 5 [61]. The ruthenium imido complex 5 (M = Ru, R = Ph) gives the bis-imido complex 1 (M = Ru, R = Ph) by reaction with excess nitrobenzene in boiling benzene [61]. On the other hand, even the thermal disproportionation of 5 under an inert atmosphere and in solution leads to the formation of 1 and other uncharacterised products [62]. It has been proposed that the complexes 1-5 are connected via the sequence of reactions reported in Scheme 9 [56] ... 

Application of the more electron deficient complex Ru(TPFPP)CO as a catalyst for such imido transfer reactions with PhINTs as donor, in the absence of pyrazole, led to reasonable yields of the corresponding aziridines and amides ". For example, aziridination of allylbenzene, cyclooctene and... 

The reaction of [Ru3(GO)n] dianion with molybdenum bis(imido) complexes [Mo(NAr)2Gl2(dme)] led to the isolation of new high-low valent clusters Ru3(GO)i2 Mo(NAr)2 (Ar = G6H3Me2-2,6 163). These compounds are unstable in polar solvents, such as THF, which may reflect the strong polarization of the Ru-Mo bonds and the electron deficiency at the molybdenum center. 

The ruthenium complex [Ru(NH3)5NH] + is not considered to be a nitrene complex but rather a species where an imido-group is co-ordinated. The mechanism accounts for the fact that no free ammonia was observed, so that N—N bond cleavage must have occurred after the Ru—N bond was formed. 

The reaction of [Ru(NH3)s(OHa)] + with hydrazoic acid has as its first step an easy substitution at ruthenium to give [Ru(NH3)5(N3H)] +. This decomposes to [Ru(NH3)6(NH)] + plus dinitrogen. The main interest here, and in other similar cases, is whether this species behaves as an imido (19) or a nitrene (20) derivative. The chemical characteristics of the present intermediate indicate that it acts as an imido-complex. ... 

---