Issue 5, 2001

First report on thermally induced nitro → nitrito(O,O) linkage isomerization in diamine complexes of nickel(II) in the solid state: X-ray single crystal structural analyses of nitro and nitrito isomers

Abstract

The brown nitro isomer, trans-[NiL2(NO2)2], 1 (L =  N,N′-dipropyl-1,2-diaminoethane), was synthesized by adding L to a suspension of K4[Ni(NO2)6]·H2O in methanol. Complex 1 is metastable at ca. 298 K and transforms slowly to the greenish blue nitrito(O,O) isomer, cis-[NiL2(O2N)](NO2), 2. This transformation is accelerated with increasing temperature and slowed down on lowering the temperature (< 283 K). Complex 2 shows a reversible phase transition, 23 (cooling: ΔH  = 8.150 ± 0.004 kJ mol−1; 266–255 K; heating: ΔH  =  −7.960 ± 0.003 kJ mol−1; 257–268 K), whereas complex 1 does not exhibit any such transition. The structures of 1, 2 and 3 have been characterized by X-ray single crystal structure analyses, which reveal that 1 and 2/3 are nitro and nitrito(O,O) linkage isomers, respectively. Complexes 2 and 3 have essentially similar structures and their reversible transformation is supposed to be due to the change in thermal motion of the side chains on variation of temperature.

Supplementary files

Article information

Article type
Paper
Submitted
09 Oct 2000
Accepted
26 Jan 2001
First published
12 Apr 2001

New J. Chem., 2001,25, 764-768

First report on thermally induced nitro → nitrito(O,O) linkage isomerization in diamine complexes of nickel(II) in the solid state: X-ray single crystal structural analyses of nitro and nitrito isomers

I. R. Laskar, D. Das, G. Mostafa, T. Lu, T. Keng, J. Wang, A. Ghosh and N. R. Chaudhuri, New J. Chem., 2001, 25, 764 DOI: 10.1039/B008254F

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