Nitrosyl metal complexes, organometallic

Few successful reactions are known by which an organometallic nitrosyl product has been formed from the condensation of mononuclear metal nitrosyl complexes. The unique cluster (Tj -C5H5)3Mn3(NO)4 (39), which contains the only i3-NO known (7) (40), is prepared using photochemical or thermal (41) decarbonylation of (Tj -C5H5)2Mn2(CO)2(NO)2 [Eq. (25)]. The use of the redox condensation of a nitrosyl carbonylmetallate with a neutral metal carbonyl cluster to produce a nitrosyl cluster has... 

Keeping our target of homogeneous catalysis in mind, we adopted a broad definition of organometallic complexes and included compounds without metal-carbon bonds (e. g., metal-phosphine and metal-nitrosyl complexes) as far as they retain the structural and reactivity features of typical organometallic compounds. Recent developments, e. g., the substitution of phosphine by carbene ligands (cf Section 3.1.1.1), support the validity of this view. 

The discovery that the nitrosyl ligand is capable of binding to transition metals in two isomeric valence forms1 is one of the most dramatic recent developments in organometallic chemistry. Since bent NO donates 2 fewer electrons to the metal than the linear isomer does, linear-bent tautomerism raises the possibility of coordinative unsaturation and catalysis.2 In fact, complexes of nitric oxide are receiving increasing attention as catalysts,3 since they are more reactive than the corresponding carbonyls.4... 

Apart from their natural biological functions various metal nitrosyls (including organometallic dinitrosyl complexes of Cr and Mo) proved to be very convenient carriers supplying nitric oxide to various biological targets and are presently widely introduced into the therapy as vasodilators and in cancer treatment [350-352], see the chapter by Morris et al. in this volume of S B. 

As yet there is little information available on the frequency of the metal-nitrogen stretching and M—N—O deformation modes in nitrosyl complexes. Such data as appertain to the organometallic species are listed in Table V. It should be noted that, with the possible exception of the data for Co(NO)(CO)3, for which isotopic substitution results are available, there is no certain way of distinguishing between the M—N stretch and the M—N—O bend in metal nitrosyls from infrared data alone, and this problem is likely to remain unresolved until Raman data are available on such complexes. 

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