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| Title: | Magnetic properties in high-spin mononuclear manganese(III) inverted N-confused porphyrin complexes: Antiferromagnetic interaction of Mn(2-NCH 2CH=CH 2NCTPP)Br versus ferromagnetic interaction of Mn(2-NCH 2-p-C 6H 4-CO 2CH 3NCTPP)Br |
| Authors: | Yang, C., Tsai, M.Y., Hung, S.-W., Chen, J.-H., Wang, S.-S., Tung, J.-Y. |
| Contributors: | Department of Chemistry, Tunghai University |
| Keywords: | Antiferromagnetic interaction;Ferromagnetic interaction;Manganese(III) N-confused porphyrin;SQUID;X-ray diffraction |
| Date: | 2012 |
| Issue Date: | 2013-05-14T09:02:28Z (UTC)
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| Abstract: | 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-NCH 2-p-C 6H 4-CO 2CH 3NCTPP); 5], paramagnetic bromo(2-aza-2-(4′- methyl methylbenzoate)-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N,N′, N?) manganese(III) [Mn(2-NCH 2-p-C 6H 4-CO 2CH 3NCTPP)Br; 7], and paramagnetic bromo(2-aza-2-allyl-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N,N′, N?) manganese(III) [Mn(2-NCH 2-CHCH 2NCTPP)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 (dz2) BrAA (p z) H(39D) (s) C(39B) N(4B) C(16B) C(17B) 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 (dz2) BrC (p z) ⊥ H(45B) (s) C(45A) N(4A) C(18A) C(17A) MnA superexchange pathway in 7. ? 2012 Elsevier Ltd. All rights reserved. |
| Relation: | Polyhedron 37 (1) , pp. 1-8 |
| Appears in Collections: | [化學系所] 期刊論文
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