Diazo ligands

For example, the substituted aniline Ar-NH2 (Ar = />-CH3OC6H4) reacts with the ruthenium nitrosyl complex Ru(bpy)2(Cl)(NO)2+ (bpy = 2,2 -bipyridine) to give a complex of the diazo ligand, namely Ru(bpy)2(Cl)(NNAr)2+ (57). Upon employing the 15N labeled nitrosyl complex Ru(bpy)2Cl(15NO)2+ this reaction resulted in the 15N coordinated product, Ru(bpy)2Cl(15NNAr)2+, demonstrating that the reaction occurs within the metal complex coordination sphere. When the reactions were conducted in non-protic solvents, these nucleophile-nitrosyl adducts could be isolated. 

X-ray photoelectron spectroscopy, 139 Diazo ligands, 100 Dicarbonyl compounds reaction with amines aza macrocycles from, 902... 

Complexes which probably contain a diazo ligand coordinated in an end-on fashion were obtained via displacement reactions of Cp Mn(CO)2(THF)114 Note that the organic by-product is not the expected tetra-(ethoxycarbonyl)ethylene but its hydrogenated derivative 47. 

Herrmann s group (Bell et al., 1982 Herrmann et al., 1983 Herrmann and Ihl, 1983) as well as Curtis et al. (1986) reported on similar reactions that result in more complex products. These authors investigated the reactions of molybdenum- and tungsten-containing carbonyl and pentamethylcyclopentadienyl ligands with dialkyldiazomethanes in which the diazo ligands were found to be bonded at both N-atoms and to be asymmetrical, as shown in 10.71. 

Diazo ligands will also form jr-bonded complexes to platinum(O). ... 

Square-planar trans-[ vC (N2C5CI4) (PPh3)2] reacts with phosphines, phosphites, isocyanides, nitrosyl, and diazonium to form five-co-ordinate species, whereas CO and SO2 displace the diazo-ligand, giving square-planar products. ... 

Ru(OAr)Br(PPh3)2] cyclometallated diazo ligand, trans P OC6H4Me-4-N=NC6H4 2.112 (5) 113 xiii... 

Cyano-de-diazoniations of the Sandmeyer type have been used for the synthesis of aromatic nitriles for many decades (example Clarke and Reed, 1964), as cyanide ions are comparable to bromide and iodide in many respects. A homolytic cyano-de-diazo-niation that does not use metal ions as reductant or ligand transfer reagent was described by Petrillo et al. (1987). They showed that substituted diazosulfides (XC6H4 — N2 — SC6H5), either isolated or generated in situ from arenediazonium tetrafluoroborates and sodium benzenethiolate, react with tetrabutylammonium cyanide in dimethylsulfoxide under photon stimulation, leading to nitriles (XC6H4CN). The method worked well with eleven benzenediazonium ions substituted in the 3- or 4-position, and was also used for the synthesis of phthalo-, isophthalo-, and tere-... 

Abstract The dirhodium(II) core is a template onto which both achiral and chiral ligands are placed so that four exist in a paddle wheel fashion around the core. The resulting structures are effective electrophilic catalysts for diazo decomposition in reactions that involve metal carbene intermediates. High selectivities are achieved in transformations ranging from addition to insertion and association. The syntheses of natural products and compounds of biological interest have employed these catalysts and methods with increasing frequency. 

Afonso, Gois, and co-workers followed this report with an unexpected decarbonylation of diazo-acetamides (Scheme 9.14) using 43-NHC (Fig. 9.8) [58]. The reaction generated three different products, with low selectivity for the decarbonylated product. The authors tested other substrates with different R groups and bulk at the amine position but found no correlation to the amount of decarbonylation product formed. However, 43-IPr was more selective than 43-SIPr for the decarbonylation product. The authors attributed the decarbonylation to the axial coordination of the NHC ligand to the dirhodium (11) complexes. 

Scheme 10.74 Rh-catalysed intramolecular C-H insertions of y-alkoxy-a-diazo-P-keto esters with sulfonamide ligands.

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