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Abstract
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Two mononuclear rhenium coordination compounds with hydrazone ligand, [ReOBr2(PPh3)(HL)]⋅(CH3CN) (1)
and [ReCl2(PPh3)2(HL)]⋅(CH3CN) (2), were synthesized by the reaction of ReOBr3(PPh3)2 or ReOCl3(PPh3)2 with
H2L in acetonitrile (H2L = (E)-N’-(1-(4‑hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)ethylidene)picolinohydrazide).
Compounds 1 and 2 were characterized by spectroscopic methods and their structures were determined by single
crystal X-ray analysis. Structural studies indicated that despite the similarity of the reactions and structures, the
oxidation state of rhenium ion in 1 is mainly Re(V) but, in compound 2 it is reduced to Re(III) during the
synthesis procedure. The hydrazone ligand in these compounds has similar coordination mode and it is coordinated
as a bidentate N- and O-donor mononegative ligand, HL-1. TGA analysis showed that these compounds
are stable up to 200 ◦C and they decompose in two steps in the range of 200–700 ◦C. The intermolecular interactions
in these compounds were investigated by Hirshfeld surface analysis which revealed there are several
intermolecular C H⋅⋅⋅N, C H⋅⋅⋅X (X = Br and Cl) and C H⋅⋅⋅π interactions which contribute in the stabilization
of the crystal structures.
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