title: Formation of bis(μ-tetrazolato)dinickel(II) complexes with N,N,O-donor Schiff bases via in situ 1,3-dipolar cyclo-additions: isolation of a novel bi-cyclic trinuclear nickel(II)-sodium(I)-nickel(II) complex.
abstract: A dinuclear and a novel bi-cyclic hetero trinuclear bis(μ-tetrazolato) bridged nickel(II) Schiff base complexes [Ni2(L(1))2(PTZ)2] (1) and [Ni2(L(2))2(PTZ)2Na(H2O)]ClO4·H2O (2) {where HL(1) = 2-((2-(dimethylamino)ethylimino)methyl)-6-methoxyphenol, HL(2) = 2-((2-(methylamino)ethylimino)methyl)-6-methoxyphenol and HPTZ = 5-(2-pyridyl)tetrazole} have been synthesized by in situ 1,3-dipolar cyclo-addition and characterized by spectral analysis, X-ray crystallography, and variable-temperature magnetic susceptibility measurements. Both the complexes crystallize in monoclinic space group P2(1)/c. Both the complexes feature double μ-NN'-tetrazolato bridged dinickel(II) structures, in which each nickel(II) is coordinated meridionally by a depronated terdentate Schiff base [(L(1))(-) for 1 and (L(2))(-) for 2] and two nitrogen atoms of the (PTZ)(-). A nitrogen atom from a symmetry related bridging (PTZ)(-) coordinates to complete the distorted octahedral geometry of nickel(II). The phenoxo and methoxo oxygen atoms from two [NiL(2)] units and a water molecule coordinate to a sodium(I) to form the unique bi-cyclic trinuclear nickel(II)-sodium(I)-nickel(II) core in complex 2. Very strong π···π stacking is observed in complex 2 to form a supramolecular chain. The variable-temperature (1.8-300 K) magnetic susceptibility measurements show the presence of anti-ferromagnetic coupling between two nickel(II) centers for both complexes with J = -2.14(1) cm(-1) (for 1) and J = -1.20(2) cm(-1) (for 2). To obtain a better understanding of the magnetic exchange mechanism, quantum mechanical (DFT) calculations have been performed. The calculated J values [J(theo) = -4.53 cm(-1) (for 1) and J(theo) = -2.48 cm(-1) (for 2)] are in agreement with the values obtained experimentally.
authors.affiliation: Department of Chemistry, Inorganic Section, Jadavpur University, Kolkata - 700 032, India. shouvik.chem@gmail.com.
authors.forename: Mithun
authors.initials: M
authors.lastname: Das
authors.forename: Sudipta
authors.initials: S
authors.lastname: Chatterjee
authors.forename: Klaus
authors.initials: K
authors.lastname: Harms
authors.forename: Tapan Kumar
authors.initials: TK
authors.lastname: Mondal
authors.forename: Shouvik
authors.initials: S
authors.lastname: Chattopadhyay
mesh_terms: D004563:Electrochemistry; D060328:Magnetic Phenomena; D008958:Models, Molecular; D008968:Molecular Conformation; D009532:Nickel / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011789:Quantum Theory; D012545:Schiff Bases / Q000737:chemistry; D012964:Sodium / Q000737:chemistry*; D013057:Spectrum Analysis
chemical_list: D009942:Organometallic Compounds; D012545:Schiff Bases; D009532:Nickel; D012964:Sodium