Structure and magnetic properties of carbonate-bridged five-coordinate nickel(ii) complexes controlled by solvent effect

Abstract

CO2 and HCO3- react with the dinuclear hydroxo-complex [Ni(mcN3)(mu-OH)]2(PF6)2 (mcN3 = 2,4,4,9-tetramethyl-1,5,9-triazacyclododec-1-ene) to form micro-CO3 bridged nickel(II) complexes, [{Ni(mcN3)}2(mu-CO3)](PF6)2 (1a) with a symmetric core in which both nickel atoms are five-coordinate and [Ni(mcN3)(mu-CO3)Ni(mcN3)(MeCN)](PF6)2 (1b) with an asymmetric dinuclear core containing five- and six-coordinate nickel atoms. The magnetic behaviour indicates the existence of antiferromagnetic coupling between the metallic centres. A substantial increase in the value of J occurs when the symmetric five-coordinate nickel species transforms to an asymmetric five- and six-coordinate species by axial coordination of acetonitrile.

Reactions of the Terminal NiII−OH Group in Substitution and Electrophilic Reactions with Carbon Dioxide and Other Substrates: Structural Definition of Binding Modes in an Intramolecular NiII···FeIIBridged Site

“…Prior reactions of Ni II with CO 2 have involved only binuclear hydroxo-bridged complexes, which lead to binuclear products containing µ 2 :η 3 -CO 3 bridges with one or two chelate rings 30,31,49. In another case, reaction in methanol affords a µ 2 :η 2 methylcarbonate bridge 33.…”

Magneto-structural properties of carbonato-bridged copper(ii) complexes: fixation of atmospheric CO2

“…35,36 The chemical fixation and activation of CO 2 by metal complexes may lead to the development of certain devices that can eliminate the CO 2 present in the air and hence control its concentration and reduce environmental problems due to the greenhouse effect. 6,17,18,25,38 The bonding modes of the carbonato bridging ligand include complexes with dinuclear m 2 -CO 3 , 2-4,6,10,12-18 trinuclear m 3 -CO 3 , 5,[7][8][9]11,16,[18][19][20][21][22][23][24]38,39 and tetranuclear m 4 -CO 3 24-27 coordination modes, as well as 1D, 2D and 3D-dimensional structures. 37 The coordination chemistry of the carbonato ligand in transition metal complexes is very rich due to the versatility of the planar carbonate anion to act as a bridging ligand and hence bind more than one metal ion simultaneously.…”

Carbonato-bridged heteronuclear NiII2LnIII2 (Ln=Tb, Dy, Ho, Er, Tm, Yb, Lu) complexes synthesized by fixation of atmospheric CO2 – Structural and magnetic studies

“…Moreover, on complexation the strong phenolic stretching vibration m(C-O) presents at 1252 cm À1 in H 2 L was shifted to lower frequencies in heteronuclear compounds and appeared at 1218-1216 cm À1 confirming the involvement of the phenolic oxygen in the metal-ligand bonding. In the FTIR spectra of complexes 1-7 the characteristic frequencies of coordinating carbonato groups m asym (CO 2 ) and m sym (CO 2 ), as well as, carboxylate groups m asym (OCO) and m sym (OCO) overlapped and appeared at about 1548 and 1304 cm À1 , respectively [57][58][59][60]. In the low frequency regions the new band observed at around 572 cm À1 can be attributed to m(M-O) vibration.…”