Nickel(II)-induced activation of a carbon–nitrogen single bond(s) of a co-ordinated ligand by hydroxylated substrates: generation of mono- and bi-nuclear complexes with modified ligand frameworks†

Content Provider	Semantic Scholar
Author	Bhattacharyya, Sudeep Ghosh, Dipesh Endo, Akira Shimizu, Kunio Weakley, Timothy J. R. Chaudhury, Muktimoy
Copyright Year	1999
Abstract	In the presence of some hydroxylated compounds as substrates, complexations of nickel(II) with the pentadentate N4S ligand methyl 2-{2-bis[(3,5-dimethylpyrazol-1-ylmethyl)amino]propylamino}cyclopent-1-ene-1-carbodithioate (Hmmpcd) having a pair of flexible pyrazolyl arms proceeded through unusual reaction paths involving C–N bond cleavage process. For example, the product 1 obtained in methanol as substrate is a square planar compound with a modified ligand structure that includes a methoxy group provided by the solvent. With an acidic substrate viz. phenol the product is also a square planar compound 2 with one of the pendant arms of Hmmpcd being replaced by a hydrogen atom. On the other hand, in the presence of a basic substrate viz. ethanolamine the ligand undergoes more extensive breakdown to generate a binuclear complex 3 with a bridging pyrazolyl group. These complexes 1–3 were characterised by X-ray crystallography and 1H NMR spectroscopy. Compound 1 displayed a reversible one-electron NiII → NiI reduction at E½ ≈ –1.0 V vs. Ag–AgCl reference as established by cyclic voltammetry and combined coulometry/EPR experiments. Such reversibility of electron transfer is unusual for a square-planar nickel(II) compound in an acyclic ligand environment. Stabilisation of the reduced nickel(I) species by methoxy group co-ordination provides a probable explanation for this reversible electron transfer.
Starting Page	3859
Ending Page	3865
Page Count	7
File Format	PDF HTM / HTML
DOI	10.1039/A905268B
Alternate Webpage(s)	https://people.uwec.edu/bhattas/nickel_N4S_2.pdf
Alternate Webpage(s)	https://doi.org/10.1039/A905268B
Language	English
Access Restriction	Open
Content Type	Text
Resource Type	Article