Isomerisation in Bis(diethyltriamine)nickel(II) Thiocyanate: Synthesis, Solid-state Interconversion and X-Ray Crystallographic Study of syn-fac and mer Isomers

Alok K. Mukherjee, Subratanath Koner, Ashutosh Ghosh, Nirmalendu Ray Chaudhuri, Monika Mukherjee, Alan J. Welch

Research output: Contribution to journalArticle

Abstract

Bis(diethylenetriamine)nickel(II) thiocyanate has been found to undergo a phase transition (162-180 °C, ΔH = 29.4 kJ mol-1) involving a low-temperature ordered system (sym-fac isomer 1) and a high-temperature disordered system (mer isomer 2). Both isomers have been synthesised and characterized by X-ray crystallography. Isomer 2 is metastable and reverts to 1 in the presence of a humid atmosphere (relative humidity ca. 60% or more) as heterogeneous catalyst. Isomer 1 crystallizes in the triclinic system, space group P1̄, with a = 7.240(2), b = 8.225(3), c = 8.766(3) Å, α = 63.27(2), β = 74.07(4), γ = 65.56(2)°, Z = 1, R = 0.024. In the cationic unit, the ligand geometry around nickel(II) is nearly octahedral. Two chelating tridentate diethylenetriamine (dien) molecules with terminal amino groups in cis and secondary amino groups in trans position define the sym-fac geometry. Isomer 2 crystallizes in the cubic system, space group F4̄3m, with a = b = c = 12.373(3) Å, Z = 4, R = 0.112. The cation [Ni(dien)2]2+ is three-fold disordered about the [111] direction and the two tridentate dien molecules are co-ordinated meridionally.

Original languageEnglish
Pages (from-to)2367-2371
Number of pages5
JournalJournal of the Chemical Society, Dalton Transactions
Issue number16
DOIs
Publication statusPublished - 21 Aug 1994

ASJC Scopus subject areas

  • Chemistry(all)

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