Five-coordinate metal(II) complexes based pyrazolyl ligands. (18th April 2015)

• Record Type: Journal Article
• Authors: Massoud, Salah S.; Louka, Febee R.; David, Regan N.; Dartez, Merlin J.; Nguyn, Quang L.; Labry, Nicholas J.; Fischer, Roland C.; Mautner, Franz A.
• Is Part Of: Polyhedron. Volume 90(2015)
• Page Start: 258
• Page End: 265
• Publication Date: 2015-04-18
• Subjects: Cobalt -- Nickel -- Copper -- Thiocyanato -- Crystal structure; Chemistry, Inorganic -- Periodicals; Chimie inorganique -- Périodiques; Organometaalverbindingen; Anorganische chemie; 546.05
• DOI: 10.1016/j.poly.2015.02.014
• Languages: English
• ISSNs: 0277-5387

Abstract

Graphical abstract: Five new mononuclear five-coordinate N -thiocyanato and azido Co(II), Cu(II) and Ni(II) complexes based on pyrazolyl ligands are synthesized and structurally characterized. The role of metal ion and structural parameters of the amine coligands in stabilizing the square pyramidal versus trigonal bipyramidal geometry are discussed. Abstract: The reactions of pyrazole based ligands with M(II) perchlorate hexahydrate in the presence of NH4 NCS afforded the mononuclear complexes [Co(Bzbedmpza)(NCS)2 ]·¾CH3 COCH3 (1 ), [Ni(Bzbedmpza)(NCS)2 ] (2 ), [Cu(Bzbedmpza)(NCS)2 ] (3 ) and [Cu(Mebedmpza)(NCS)2 ] (4 ), and in the presence of NaN3, the complex [Cu(tedmpza)(N3 )]ClO4 (5 ) was isolated where Bzbedmpza = N -benzyl-bis(3, 5-dimethyl-2-(pyrazol-1H-yl)ethyl)amine, Mebedmpza = N -methyl-bis(3, 5-dimethyl-2-(pyrazol-1H-yl)ethyl)amine and tedmpza = tris(2, 5-dimethyl-ethyl-pyrazol-1H-yl)amine. The complexes were structurally characterized by elemental microanalyses, IR and UV–Vis spectroscopy and by single crystal X-ray crystallography. The complexes2 –5 display distorted SP geometry, whereas the cobalt(II) complex1 has a distorted TBP. Also, all the thiocyanato complexes1 –4 are coordinated to the central metal ions through N -terminal thiocyanate. The stability of any of the two possible limiting geometries (SP versus TBP) including nature of the central metal ion and the structural parameters of the amine coligands (steric effect, nature of chelate ring sizes and skeleton of the coligand) are analyzed as a function of τ values.