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|標題:||Magnetic properties in high-spin mononuclear manganese(III) inverted N-confused porphyrin complexes: Antiferromagnetic interaction of Mn(2-NCH2CH=CH2NCTPP)Br versus ferromagnetic interaction of Mn(2-NCH2-p-C6H4-CO2CH3NCTPP)Br||作者:||Yang, C.
|關鍵字:||X-ray diffraction;Manganese(III N-confused porphyrin;Ferromagnetic;interaction;Antiferromagnetic interaction;SQUID;epr-spectra;paramagnetic resonance;trivalent manganese;tetraphenylporphyrin;activation;isomer;states||Project:||Polyhedron||期刊/報告no：:||Polyhedron, Volume 37, Issue 1, Page(s) 1-8.||摘要:||
The crystal structures of diamagnetic (2-aza-2-(4'-methyl methylbenzoate)-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N,N',N '') nickel(II) [Ni(2-NCH2-p-C6H4-CO2CH3NCTPP); 5], paramagnetic bromo (2-aza-2-(4'-methyl methylbenzoate)-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N,N',N '') manganese (III) [Mn(2-NCH2-p-C6H4-CO2CH3NCTPP)Br; 7], and paramagnetic bromo(2-aza-2-allyl-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N,N',N") manganese(III) [Mn(2-NCH2-CH=CH2NCTPP)Br; 6] were determined. The coordination sphere around Ni(II) in 5 is described as four-coordinate square-planar, whereas for Mn(III) in 6 and 7, it is a five-coordinate square pyramid (SPY-5) in which the unidentate Br- ligand occupies the axial site. The g(eff) value of 10.7 (or 11.1) measured from the parallel polarization of the X-band EPR spectra at 4 K is consistent with a high spin mononuclear manganese(III) centre (S = 2) in 6 (or 7). The magnitude of the axial (D) zero-field splitting (ZFS) for the mononuclear Mn(III) centre in 6 (or 7) was determined approximately as -3.3 cm(-1) (or -0.92 cm(-1)) by paramagnetic susceptibility measurements. Owing to the weak C(39A)-H(39B)...BrBA [or C(45A)-H(45B)...BrC] intermolecular hydrogen bonds, the mononuclear Mn(III) neutral molecules of 6 (or 7) are arranged in a dimeric network. A weak Mn(III)...Mn(III) antiferromagnetic interaction (J(AF) = -0.02 cm(-1)) operates via a MnAA (d(2)(2)) parallel to BrAA ((P)z) parallel to H(39D) (s) parallel to C(39B) parallel to N(4B) parallel to C(16B) parallel to C(17B) parallel to MnBA superexchange pathway in complex 6. Moreover, a weak Mn(III)...Mn(III) ferromagnetic interaction (J(F) = 0.58 cm(-1)) operates via a MnC (d(2)(2)) parallel to BrC (p(z)) perpendicular to H(45B) (s) parallel to C(45A) parallel to N(4A) parallel to C(18A) parallel to C(17A) parallel to MnA superexchange pathway in 7. (C) 2012 Elsevier Ltd. All rights reserved.
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