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Structural Elucidation of tmeda‐Solvated Alkali Metal Diphenylamide Complexes
Author(s) -
Kennedy Alan R.,
Klett Jan,
O'Hara Charles T.,
Mulvey Robert E.,
Robertson Gemma M.
Publication year - 2009
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200900782
Subject(s) - chemistry , denticity , isostructural , crystallography , coordination sphere , tetramethylethylenediamine , molecule , ligand (biochemistry) , alkali metal , amide , lithium atom , coordination complex , metal , stereochemistry , crystal structure , medicinal chemistry , organic chemistry , ion , biochemistry , receptor , ionization
Lithium, sodium and potassium salts of diphenylamine have been prepared by using a deprotonative route and characterised in both, solid state (by X‐ray crystallography) and solution (by NMR spectroscopic studies). In each case the metal atom's coordination sphere is completed by coordination to the synthetically important co‐ligand N , N , N′ , N′ ‐tetramethylethylenediamine (tmeda). Complexes 1 and 2 [{(tmeda)M(NPh 2 )} 2 ] (M = Li for 1 , Na for 2 ) can be prepared by treating 1 mol.‐equiv. of the parent amine with an equimolar quantity of n BuM and tmeda in hexane solution. In the solid state, 1 and 2 are essentially isostructural, being dimeric with a four‐atom M–N–M–N framework. The coordination sphere of each M atom is completed by a bidentate tmeda molecule. Complex 3 [{(tmeda) 3/2 K(NPh 2 )} 2 ] has been prepared in a similar way to 1 and 2 except that benzylpotassium has been utilised as the metallating agent. In addition, 4 mol‐equiv. of tmeda is required to fully solubilise the heavy alkali metal amide mixture. In the solid state, 3 exists as a polymeric array of dinuclear K–N–K–N rings. Akin to 1 and 2 , the K atom is coordinated to a bidentate tmeda molecule; however, each K atom is also bound to another tmeda molecule that acts as a monodentate bridge, thus producing the coordination polymer. Crystalline 1 and 2 are soluble in C 6 D 6 ; hence, NMR spectroscopic studies could be performed. These show that the solid‐state structure appears to stay intact in arene solution. On the other hand, 3 is not soluble in C 6 D 6 ; so solution studies have been performed in [D 8 ]thf. These studies reveal that 3 readily looses tmeda during in‐vacuo isolation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)