Ruthenium nitrosyl complexes structures

Table 1.9 Ruthenium nitrosyl complexes structural and IR data ...

Table 1.9 summarizes structural data for a number of ruthenium nitrosyl complexes, along with IR data [121, 122],... 

Fig. 5.6 Structures of some typical ruthenium nitrosyl complexes.

Videla M, Jacinto JS et al (2006) New ruthenium nitrosyl complexes with tris(l-pyrazolyl) methane (tpm) and 2,2 -bipyridine (bpy) coligands. Structure, spectroscopy, and electrophilic and nucleophilic reactivities of bound nitrosyl. Inorg Chem 45 8608-8617... 

Tfouni E, Krieger M, McGarvey BR, Franco DW. Structure, chemical and photochemical reactivity and biological activity of some ruthenium amine nitrosyl complexes. Coord Chem Rev 2003 236 57-69. 

Miranda KM, Bu X, Lorkovic IM, Ford PC. Synthesis and structural characterization of several ruthenium porphyrin nitrosyl complexes. Inorg Chem 1997 36 4838. 

The normal classification of material by oxidation state is inappropriate for nitrosyl complexes because the oxidation state concept is very much a formalism for them. Instead we shall use the generally accepted [M(NO)x] + classification in which x is the number of coordinated NO groups and n the number of metal d electrons, the latter being calculated on the basis that NO+ is the coordinated moiety. As will be apparent, osmium complexes within each such category do in fact show considerable similarities of structure and reactivity, and also with their ruthenium analogues. Osmium is unusual in forming an [M(NO)]5 type of complex. 

Figure 1 Nitrosyl ruthenium complexes structures explored in this work.

Figure 2 Nitrosyl macrocyclic ruthenium complexes structure. (A) frans-[RuCI [15]ane4) NO] " and (B) frans-[RuCI cyclam)NO]. The colored circles represent atoms in the chemical structure (cyan (light gray in the print version) carbon blue (black in the print version) nitrogen green (gray in the print version) chlorine red (dark gray in the print version) oxygen white hydrogen, and gray ruthenium).

The structure of CpCr(NO)2 is remarkable in that it demonstrated unequivocally for the first time the existence of bent M—N—O bonds in a nitrosyl complex. Although bent M—N—O bonds have been claimed in Co(NO)(S2CNMe2)2 ( ) and in a number of ruthenium complexes (48) the evidence is not conclusive. Electron spin resonance measurements on... 

Besides ruthenium porphyrins (vide supra), several other ruthenium complexes were used as catalysts for asymmetric epoxidation and showed unique features 114,115 though enantioselectivity is moderate, some reactions are stereospecific and treats-olefins are better substrates for the epoxidation than are m-olcfins (Scheme 20).115 Epoxidation of conjugated olefins with the Ru (salen) (37) as catalyst was also found to proceed stereospecifically, with high enantioselectivity under photo-irradiation, irrespective of the olefmic substitution pattern (Scheme 21).116-118 Complex (37) itself is coordinatively saturated and catalytically inactive, but photo-irradiation promotes the dissociation of the apical nitrosyl ligand and makes the complex catalytically active. The wide scope of this epoxidation has been attributed to the unique structure of (37). Its salen ligand adopts a deeply folded and distorted conformation that allows the approach of an olefin of any substitution pattern to the intermediary oxo-Ru species.118 2,6-Dichloropyridine IV-oxide (DCPO) and tetramethylpyrazine /V. V -dioxide68 (TMPO) are oxidants of choice for this epoxidation. 

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