Versatile Reactivity of MnII Complexes in Reactions with N-Donor Heterocycles: Metamorphosis of Labile Homometallic Pivalates vs. Assembling of Endurable Heterometallic Acetates

Reaction of 2,2′-bipyridine (2,2′-bipy) or 1,10-phenantroline (phen) with [Mn(Piv)2(EtOH)]n led to the formation of binuclear complexes [Mn2(Piv)4L2] (L = 2,2′-bipy (1), phen (2); Piv− is the anion of pivalic acid). Oxidation of 1 or 2 by air oxygen resulted in the formation of tetranuclear MnII/III complexes [Mn4O2(Piv)6L2] (L = 2,2′-bipy (3), phen (4)). The hexanuclear complex [Mn6(OH)2(Piv)10(pym)4] (5) was formed in the reaction of [Mn(Piv)2(EtOH)]n with pyrimidine (pym), while oxidation of 5 produced the coordination polymer [Mn6O2(Piv)10(pym)2]n (6). Use of pyrazine (pz) instead of pyrimidine led to the 2D-coordination polymer [Mn4(OH)(Piv)7(µ2-pz)2]n (7). Interaction of [Mn(Piv)2(EtOH)]n with FeCl3 resulted in the formation of the hexanuclear complex [MnII4FeIII2O2(Piv)10(MeCN)2(HPiv)2] (8). The reactions of [MnFe2O(OAc)6(H2O)3] with 4,4′-bipyridine (4,4′-bipy) or trans-1,2-(4-pyridyl)ethylene (bpe) led to the formation of 1D-polymers [MnFe2O(OAc)6L2]n·2nDMF, where L = 4,4′-bipy (9·2DMF), bpe (10·2DMF) and [MnFe2O(OAc)6(bpe)(DMF)]n·3.5nDMF (11·3.5DMF). All complexes were characterized by single-crystal X-ray diffraction. Desolvation of 11·3.5DMF led to a collapse of the porous crystal lattice that was confirmed by PXRD and N2 sorption measurements, while alcohol adsorption led to porous structure restoration. Weak antiferromagnetic exchange was found in the case of binuclear MnII complexes (JMn-Mn = −1.03 cm−1 for 1 and 2). According to magnetic data analysis (JMn-Mn = −(2.69 ÷ 0.42) cm−1) and DFT calculations (JMn-Mn = −(6.9 ÷ 0.9) cm−1) weak antiferromagnetic coupling between MnII ions also occurred in the tetranuclear {Mn4(OH)(Piv)7} unit of the 2D polymer 7. In contrast, strong antiferromagnetic coupling was found in oxo-bridged trinuclear fragment {MnFe2O(OAc)6} in 11·3.5DMF (JFe-Fe = −57.8 cm−1, JFe-Mn = −20.12 cm−1).

Bovine Serum Albumin Interactive One Dimensional Hexanuclear Manganese (III) Complex: Synthesis, Structure, Binding and Molecular Docking Studies

The reaction of MeO-salox (4-methoxy salicylaldehyde-oxime) with Mn(OAc)2.4H2O in methanol medium in 1:1 molar ratio and in the presence of tetra-butyl ammonium hydroxide affords a hexanuclear Complex [Mn6O2(4-MeO-salox)6(N3)2(MeOH)2(H2O)2.2H2O]n (1). Single...

Synthesis and Structural Characterisation of Lithium, Zinc, and Aluminium Pyrazolate Complexes

The reaction of nBuLi with 3,5-dimethylpyrazole (Me2pzH) in Et2O or tmeda/hexane (tmeda=N,N,N′,N′-tetramethylethane-1,2-diamine) and with 3,5-dimethyl-4-nitropyrazolate (Me2pzHNO2) in THF results in the formation of three structurally diverse lithium pyrazolates: namely an Et2O-solvated tetrameric complex [Li4(Me2pz)4(OEt2)4], bridged entirely with μ-η2:η1-pyrazolate bonding, a hexanuclear complex [Li6(Me2pz)6(tmeda)2] with four different coordination modes (μ-η1:η1, μ-η2:η1, μ3-η1:η2:η1 and μ3-η2:η2:η1), and a new polymeric compound [Li2(Me2pzNO2)2(thf)2]n, with [Li2(Me2pzNO2)2(thf)2] groups linked by –NO2 coordination. A mononuclear zinc complex [Zn(tBu2pz)2(tBu2pzH)2].1/2THF (tBu2pzH=3,5-di-tert-butylpyrazole) was prepared by reaction of tBu2pzH with ZnEt2, unidentate tBu2pz groups being stabilised by N–H⋯N hydrogen bonding. Treatment of 3,5-diphenylpyrazole (Ph2pzH) with trimethylaluminium (mole ratio 3:1) in THF led to the formation of dinuclear [AlMe2(μ-Ph2pz)]2.1/2THF.

Electrochemical sensing of nitrite using a copper–titanium oxide composite derived from a hexanuclear complex

An electrochemical nitrite ions sensor electrode, CuO–2TiO2, has been developed using single molecular precursor [Cu2Ti4(O)2(OH)4(TF)8(THF)6]·THF in aerosol assisted chemical vapour deposition technique.

Crystal structures of bis- and hexakis[(6,6′-dihydroxybipyridine)copper(II)] nitrate coordination complexes

Two multinuclear complexes synthesized from Cu(NO3)2and 6,6′-dihydroxybipyridine (dhbp) exhibit bridging nitrate and hydroxide ligands. The dinuclear complex (6,6′-dihydroxybipyridine-2κ2N,N′)[μ-6-(6-hydroxypyridin-2-yl)pyridin-2-olato-1:2κ3N,N′:O2](μ-hydroxido-1:2κ2O:O′)(μ-nitrato-1:2κ2O:O′)(nitrato-1κO)dicopper(II), [Cu2(C10H7N2O2)(OH)(NO3)2(C10H8N2O2)] or [Cu(6-OH-6′-O-bpy)(NO3)(μ-OH)(μ-NO3)Cu(6,6′-dhbp)], (I), with a 2:1 ratio of nitrate to hydroxide anions and one partially deprotonated dhbp ligand, forms from a water–ethanol mixture at neutral pH. The hexanuclear complex bis(μ3-bipyridine-2,2′-diolato-κ3O:N,N′:O′)tetrakis(6,6′-dihydroxybipyridine-κ2N,N′)tetrakis(μ-hydroxido-κ2O:O′)bis(methanol-κO)tetrakis(μ-nitrato-κ2O:O′)hexacopper(II), [Cu6(C10H6N2O2)2(CH4O)2(OH)4(NO3)4(C10H8N2O2)4] or [Cu(6,6′-dhbp)(μ-NO3)2(μ-OH)Cu(6,6′-O-bpy)(μ-OH)Cu(6,6′dhbp)(CH3OH)]2, (II), with a 1:1 NO3–OH ratio and two fully protonated and fully deprotonated dhbp ligands, was obtained by methanol recrystallization of material obtained at pH 3. Complex (II) lies across an inversion center. Complexes (I) and (II) both display intramolecular O—H...O hydrogen bonding. Intermolecular O—H...O hydrogen bonding links symmetry-related molecules forming chains along [100] for complex (I) with π-stacking along [010] and [001]. Complex (II) forms intermolecular O—H...O hydrogen-bonded chains along [010] with π-stacking along [100] and [001].