title: Reversible switching of electronic ground state in a pentacoordinated Cu(II) 1D cationic polymer and structural diversity.
abstract: Two copper(II) polymeric complexes {[Cu(HPymat)(MeOH)](NO3)}n (1) and {[Cu4(Pymab)4(H2O)4](NO3)4} (2) were synthesized with the carboxylate-containing Schiff-base ligands HPymat(-) and Pymab(-) [H2Pymat = (E)-2-(1-(pyridin-2-yl)methyleneamino)terephthalic acid, HPymab = (E)-2-((pyridine-2-yl)methyleneamino)benzoic acid]. Complex 1 is a one-dimensional Cu(II) cationic polymeric complex containing free protonated carboxylic groups and nitrate anions as counterions. Complex 2 is a zero-dimensional tetranuclear cationic Cu(II) complex containing nitrate anions as counterions. Complex 1 shows rhombic electron paramagnetic resonance (EPR) spectra in the solid state at room temperature (RT) and 77 K and tetragonal EPR spectra in dimethyl sulfoxide (DMSO) and dimethylformamide (DMF) and "inverse" EPR spectrum in CH3CN. Complex 2 shows rhombic EPR spectra in the solid state at RT and 77 K. But complex 2 shows tetragonal spectra in DMSO, DMF, and CH3CN. Thermogravimetric analysis was also performed for both complexes 1 and 2. Mean-square displacement amplitude analysis was carried out to detect librational disorder along the metal-ligand bonds in crystal structures.
authors.affiliation: Department of Chemistry, Jadavpur University , Raja S.C. Mullick Road, Kolkata-700032, West Bengal, India.
authors.forename: Ashok
authors.initials: A
authors.lastname: Sasmal
authors.forename: Eugenio
authors.initials: E
authors.lastname: Garribba
authors.forename: Corrado
authors.initials: C
authors.lastname: Rizzoli
authors.forename: Samiran
authors.initials: S
authors.lastname: Mitra
mesh_terms: D002264:Carboxylic Acids / Q000737:chemistry; D002412:Cations; D003300:Copper / Q000737:chemistry*; D008958:Models, Molecular; D009566:Nitrates / Q000737:chemistry; D011108:Polymers / Q000737:chemistry
chemical_list: D002264:Carboxylic Acids; D002412:Cations; D009566:Nitrates; D011108:Polymers; D003300:Copper