Nitrosyl complexes structures

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

Figure 11.13 Structures of polynuclear nitrosyl complexes (a) ((Cr( j -C5H5)(NO))2(M2-NH2)(M2-NO) showing linear-terminal and doubly bridging NO and (b) (Mn3( j -C5H5)3( 3-NO)3( 3-NO)] showing double-and triply-bridging NO the molecule has virtual symmetry and the average Mn-Mn distance is 250 pm (range 247-257 pm).

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

Table 2.14 Structural data for iridium nitrosyl complexes...

Principles of structure, bonding and reactivity for metal nitrosyl complexes. J. H. Enemark and R. D. Feltham, Coord. Chem. Rev., 1974,13, 339-406 (126). 

Carter, O. L., McPhail, A. T. Sim, G. A. (1967) Metal-carbonyl and metal-nitrosyl complexes. Part V. The crystal and molecular structure of the tricarbonylchromium derivative of methyl benzoate, J. Chem. Soc. A, 1619-1626. 

Surface nitrosyl complexes of TMI have been thoroughly investigated by the computational spectroscopy [22,23,32,33,36,49], and their molecular structure has been ascertained by a remarkable agreement between the theory and experiment of both vibrational (oscillation frequencies and intensities) and magnetic (g and A tensors) parameters. The calculated pNO values for the examined mononitrosyls along with the experimental frequencies are listed in Table 2.6. Analogous collation of the IR data for dinitrosyl species is shown in Table 2.7. 

In contrast, for the NO8- species the N—O bond is elongated, only slightly polarized, and the stretching frequency, vNO, decreases below 1850 cm-1. Such changes indicate that the activation consists in redistribution of the electron and spin densities within the M—NO unit, which accumulates on the nitrogen atom. Among the first series TMI, the oxidative adsorption is less common and includes only the tj1 CuNO] 11 and 171 3CrNO 6 adducts. The mechanistic implications of the electronic structures for both type of the nitrosyl complexes are discussed in the next section. 

The syntheses, structures and properties of wide varieties of metal nitrosyl complexes have been well documented [4, 5, 20-23]. However, the bulk of the complexes reviewed previously are of academic interest and only a few of these metal nitrosyl complexes have been considered as biologically effective NO donors. It was observed that the metal nitrosyls with significant NO+ character are subject to attack from a variety of nucleophiles and have hypertensive properties. This could be due to the strong trans- labilizing effect of NO. In contrast, the metal nitrosyl compounds with the general formula [M(CN)5NO]n, where the NO ligand was either neutral (for M = Co) or anionic (for M = Cr) showed no vasodilatory effect [24]. 

Fig. 5.6 Structures of some typical ruthenium nitrosyl complexes.

In this paper author reported the reactivity of newly synthesized Co(III)-nitrosyls complexes with superoxide radical to follow nitric oxide dioxygenation. Two new Co(III)-nitrosyl complexes bearing N-tetramethylated cyclam (TMC) ligands, [(12-TMC)-Com(NO)]2+ (1) and [(13-TMC)Coin(NO)]2+ (2), were synthesized via [(TMC)Con(CH3CN)]2+ + NO(g) reactions. Spectroscopic and structural characterization showed that these compounds bind the nitrosyl moiety in a bent end-on fashion. Complexes 1 and 2 reacted with K02/2.2.2-ciyptand to produce [(12-TMC)Con(N02)]+ (3) and [(13-TMC)Con(N02)]+ (4), respectively these possess 0,0 -chelated nitrito ligands. 

Osterloh, F., Saak, W, Haase, D. and Pohl, S. (1997) Synthesis, X-ray structure and electrochemical characterization of a binuclear thiolate bridged Ni-Fe-nitrosyl complex, related to the active site of NiFe hydrogenase. Chem. Commun. (Cambridge), 1997, 979-80. 

Thionitrosyl compounds are less common, but the few structurally characterized representatives suggest a close similarity to the chemistry of nitrosyl complexes. 

Several hundred crystal structures of iron porphyrin complexes have been solved and published in the past two decades. Interest has centered on nitrosyl complexes, on iron-porphyrin tt radical... 

Nitrosyl complexes of formula [Ru(NO)Cl3(diphos)] in which diphos = dppm, dppe, dppp, or (Z)-l,2-bis(diphenylphosphino)ethene have been synthesized. Although P NMR spectroscopic data are consistent with a fac isomer in each case, the solid-state structure of [Ru(NO)Cl3(dppp)]... 

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