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A Ferromagnetic Methoxido-Bridged Mn(III) Dimer and a Spin-Canted Metamagnetic μ1,3-Azido-Bridged Chain
journal contribution
posted on 2012-05-07, 00:00 authored by Subrata Naiya, Saptarshi Biswas, Michael G. B. Drew, Carlos J. Gómez-García, Ashutosh GhoshTwo new Mn(III) complexes of formulas [MnL1(N3)(OMe)]2 (1) and [MnL2(N3)2]n (2) have
been synthesized by using two tridentate NNO-donor Schiff base ligands
HL1{(2-[(3-methylaminoethylimino)-methyl]-phenol)} and
HL2 {(2-[1-(2-dimethylaminoethylimino)methyl]phenol)},
respectively. Substitution of the H atom on the secondary amine group
of the N-methyldiamine fragment of the Schiff base by a methyl group
leads to a drastic structural change from a methoxido-bridged dimer
(1) to a single μ1,3-azido-bridged 1D
helical polymer (2). Both complexes were characterized
by single-crystal X-ray structural analyses and variable-temperature
magnetic susceptibility measurements. The magnetic properties of compound 1 show the presence of weak ferromagnetic exchange interactions
mediated by double methoxido bridges (J = 0.95 cm–1). Compound 2 shows the existence of
a weak antiferromangetic coupling along the chain (J = −8.5 cm–1) through the single μ1,3-N3 bridge with a spin canting that leads to
a long-range antiferromagnetic order at Tc ≈ 9.3 K and a canting leading to a weak ferromagnetic long-range
order at Tc ≈ 8.5 K. It also exibits
metamagnetic behavior at low temperatures with a critical field of
ca.1.2 T due to the weak antiferromagnetic interchain interactions
that appear in the canted ordered phase.
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methoxido bridgesH atomligandpresenceSubstitutionexibits metamagnetic behaviorfragmentSchiff basecompound 1 showantiferromangeticDimerdimethylaminoethyliminoamine groupdimer.1.2 Tmethyl groupHLformulaexchange interactionsMnMnLanalysescmhelicalMetamagnetic8.59.3antiferromagnetic interchain interactionsantiferromagnetic order0.95polymerTctridentatecomplexsusceptibility measurementsFerromagneticphaseChainTwo
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