Synthesis and coordination chemistry of 2-(di-2-pyridylamino)pyrimidine: structural aspects of spin crossover in an Fe-II complex

Rachel S Crees, Boujemaa Moubaraki, Keith Spencer Murray, Christopher James Sumby

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Abstract

2-(Di-2-pyridylamino)pyrimidine (L), a potentially ditopic tetradentate ligand, was synthesized from commercially available di-2-pyridylamine and 2- chloropyrimidine. Despite being capable of bridging two metal atoms with bidentate chelation of both metal centres, L prefers to chelate or bridge through the more basic pyridyl donors of the di-2-pyridylamine moiety. Mononuclear trans-[Fe(NCS)(2)(L)(2)] and [Cu(L)(2)(H2O)](BF4)(2)center dot H2O complexes, and a discrete [Ag-2(L)(4)](PF6)(2) metallo-macrocycle, were isolated and structurally characterized by X-ray crystallography. A mononuclear palladium complex [PdCl2(L)]center dot(solvate), where solvate = 1/2H(2)O or CH2Cl2, was also readily obtained in 71 yield. One example of the ligand acting as a bis(bidentate) bridging ligand was observed in a dinuclear [(PdCl2)(2)(L)]center dot 3/4H(2)O complex that was obtained only in very low yield (similar to 3 ) from the reaction that produced [PdCl2(L)]center dot 1/2H(2)O. trans-[Fe(NCS)(2)(L)(2)] undergoes a temperature-dependent high-spin-low-spin crossover at similar to 205 K that was observed by X-ray crystallography and magnetic measurements, and attempts were made to understand the structural basis of this process. Despite efforts to isolate examples of L bridging two iron(II) centres, only the mononuclear trans-[Fe(NCS)(2)(L)(2)] species could be obtained.
Original languageEnglish
Pages (from-to)842 - 850
Number of pages9
JournalAustralian Journal of Chemistry
Volume65
Issue number7
DOIs
Publication statusPublished - 2012

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