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Structural studies on products of reduction of a nitro-Ni1C3N2-metallocene |
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| Authors: | R Kent Murmann Elmer O Schlemper Charles Barnes Edwin G Vassian |
| Institution: | a Department of Chemistry, University of Missouri, Columbia, MO 65211, USA b Department of Chemistry, Western Carolina University, Cullowhee, NC 28723, USA |
| Abstract: | The reduction of 12-nitro-(1,1,2,8,9,9-hexamethyl-3,7,10-14-tetraaza-4,6-oxa-5-hydra-tetradeca-2,7,10-12-tetrene)nickel(II) (Nioyl-NO2), with Zn(s) and NaOH or HCl solution or utilizing Pd-H2 under most conditions produces an intensely purplee complex ion ε(max) at 552 nm which is not the expected amine. This product was found to be a conjugated dimer ion with two Nioyls multiply bonded to a single nitrogen atom. It was shown that the initial reduction produces the amine or amine hydrochloride which oxidizes rapidly in the presence of traces of O2 under low acidity conditions to the dimer. Under high acidity conditions the amine salt is isolated. The X-ray crystal structures of three complexes are described: (Nioyl)2NH](ClO4)2·2.5CCl4, (Nioyl-NH3)2H]ZnCl4Cl·3H2O, Nioyl-NH3]H0.5(ClO4)1.5·2CH3CN·2H2O and structural differences are discussed. The 2e? reduction of (Nioyl)2N]+ with dithionite ion reversibly gives the yellow (Nioyl)2NH]+ which is extremely sensitive to air oxidation. A postulated reaction sequence is presented and discussed to explain the formation of the highly stable conjugated dimeric purple product. |
| Keywords: | Crystal structures Reduction Nickel complexes Nitro-metallocene complexes |
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