141344-08-3Relevant academic research and scientific papers
Iron carbonyl complexes of 2-(phenylazo)pyridines. The first example of a six-electron, bridging 2-(phenylazo)pyridine ligand
Ackermann, Martin N.,Naylor, Jerome W.,Smith, Eric J.,Mines, Gary A.,Amin, Neelam S.,Kerns, Michael L.,Woods, Clifton
, p. 1919 - 1926 (1992)
2-(Phenylazo)pyridines (1a-c) react with Fe2(CO)9 in THF to produce two major products, red brown Fe(CO)3(L-L′) (2a-c) and green Fe2(CO)2(L-L′)3 (3a-c), where L-L′ = 1a-c. A minor product with 3c is the lavender nitrene-capped complex Fe3(CO)9(μ3-N(C6H 5)(μ3-N(2-(5-CF3C5H 4N))) (4c). 3a also is obtained from the reaction of Fe(1a)3(PF6)2 and Na2Fe(CO)4 in THF. Hence, it is proposed that the first step in the formation of 3 from Fe2(CO)9 and 1 involves the disproportionation reaction Fe2(CO)9 + 31 → Fe(1)32+ + Fe(CO)42- + 5CO. When 3c is chromatographed, it decomposes in part to 2-(2-phenylhydrazmo)-5-(trifluoromethyl)pyridine, (5-CF3C5H3N)NHNHC6H5, in which the azo bond in 1c has been reduced to a hydrazine. Comparison of the infrared and visible spectra of 2 with those of analogous complexes of α-diimines indicates that the 2-PAP ligands are substantially better π acceptors than the α-diimines and that there is extensive mixing of the metal and ligand orbitals in the LUMO/HOMO orbitale of 2. 1H, 13C, and 19F NMR data show that the three 2-PAP ligands in 3 are inequivalent. The diiron complex 3b crystallizes in the monoclinic space group P21/n with a = 9.904 (2) A?, b = 19.069 (4) A?, c = 18.606 (2) A?, β = 101.82 (2)°, V = 3439.4 (15) A?3, and Z = 4. The two iron atoms are in different environments. One iron atom occupies an approximate octahedral environment that consists of three pyridine nitrogen atoms and three azo nitrogen atoms from three 4-CH3-2-PAP (1b) ligands. The second iron atom occupies a severely distorted octahedral environment that consists of two carbon monoxide carbon atoms and the four azo nitrogen atoms from two of the 4-CH3-2-PAP ligands. Two of the 4-CH3-2-PAP ligands bridge the two iron atoms with their azo linkages and serve as six-electron donors overall, while the other 4-CH3-2-PAP ligand acts as a conventional nonbridging four-electron donor. The azo bond lengths of the bridging ligands are comparable to those of an N-N single bond.
