Thursday, November 29, 2012

Poker de Mn, Ni, Fe, Co, Fe

Structural and Spectroscopic Trends in a Series of Half-Sandwich Scorpionate Complexes

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Paulina Levario

Fifteen half-sandwich scorpionate complexes [(L)M(NCMe)3](BF4)n (L = tris(3,5-dimethylpyrazol-1-yl)methane, TpmMe,Men = 2, 1M, M = Mn, Fe, Co, Ni; L = tris(3-phenylpyrazol-1-yl)methane, TpmPhn = 2, 2M, M = Mn, Fe, Co, Ni; L = hydrotris(3,5-dimethylpyrazol-1-yl)borate, [TpMe,Me]n = 1, 3M, M = Fe, Co, Ni; L = hydrotris(3-phenyl-5-methylpyrazol-1-yl)borate, [TpPh,Me]n = 1, 4M, M = Mn, Fe, Co, Ni) were prepared by addition of the tripodal ligands to solvated [M(NCMe)x]2+ (M = Mn, x = 4; M = Fe, Co, Ni, x = 6) precursor complexes. The product complexes were characterized by 1H NMR (except M = Mn), UV–vis–NIR, and FTIR spectroscopy. The structures of 2Mn2Ni3Fe3Co, and 4Fe were determined by X-ray crystallography. The data were consistent with complexes of high-spin divalent metal ions in idealized piano-stool geometries in all cases. Consequent lability of the acetonitrile ligands will enable use of these complexes as synthetic precursors and as catalysts. Comparison to previously reported structures of 1Fe1Co2Fe, and 2Co, the triflate salt analogues of 4Co and 4Ni, as well as related sandwich complexes (e.g., [(TpMe,Me)2M]) and solvated metal dications [M(NCMe)6]2+ reveals numerous trends in M–N bond lengths. Primary among these are the Irving–Williams series, with significant structural effects also arising from ligand charge and sterics. Systematic trends in spectroscopic data were also observed which further elucidate these issues.

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Structural and Spectroscopic Trends in a Series of Half-Sandwich Scorpionate Complexes

Shengwen Liang, Haoshuang Wang, Tapash Deb, Jeffrey L. Petersen, Gordon T. Yee, and Michael P. Jensen
Inorganic Chemistry Article ASAP
DOI: 10.1021/ic301409s
Publication Date (Web): November 19, 2012
Copyright © 2012 American Chemical Society

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