Ruthenium complexes five-coordinate

The ruthenium(III) complex of edta in which the ligand acts only as a five-coordinate species and in which an acetate arm remains free, exists in three pH-related forms ... 

Whereas d ruthenium complexes add protic nucleophiles to the C3=C4 of the butatrienylidene ligand to give alkenylallenylidene complexes (see Scheme 3.22), iridium complex 11 adds trifluoroacetic add to the C2=C3 bond to form an alkenylvinylidene complex [2, 3]. The corresponding reaction of 11 with two equivalents of HCl yields, presumably again via an alkenylvinylidene complex, a five-coordinate alkenyl(dichloro) complex with a trigonal-bipyramidal coordination geometry (Scheme 3.29) [3]. 

Thermolysis of RuPh2(TPP) at 100 °C for 30 h in benzene produces a phenyl-ruthenium(III) complex, RuPh(TPP) [155] (see Table 2). In contrast to RuPh2(P) and FePh(P) [222] no N-arylation occurred on oxidation of the five-coordinate RuPh(P) [306]. 

P. Gonzalez-Herrero, B. Weberndorfer, K. Ilg, J. Wolf, and H. Werner, The Sensitive Balance Between Five-Coordinate Carbene Ruthenium Complexes and Six-Coordinate Carbyne Ruthenium Complexes Formed from Ruthenium Vinylidene Precursors, Organometallics 20, 3672-3685 (2001). 

The first examples of C-H activation of an NHC ligand by TMs were reported by Hitchcock and Lappert and centered on ruthenium and iridium. [RuCl2(PPh3)3] reacted with the dimeric carbene (217) in xylene at 140 °C to give the five-coordinate monocarbeneruthenium (II) complex (218),... 

Ruthenium bis (hydrogen dihydride), reacted with alkyl and aryl halides to form a five-coordinate complex ... 

Baiker and co-workers reported that the complex tranj-[Ru(Cl)2(dppe)2] (3) (dppe = l,2-bis(diphenylphosphino)ethane) catalyzes the formation of DMF very efficiently, despite the insolubility of the complex in SCCO2 [31]. They were even able to use a heterogenized silica-grafted ruthenium complex, which was obtained from the five-coordinated precursor 4 and tetraalkoxysi-lanes in a sol-gel process [32]. With these catalysts, the reaction occurs in the liquid dimcarb phase. The fact that high rates can be achieved with such heterogenized metal complexes makes them attractive materials for other processes involving SCFs or compressed gases. 

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