Magneto-structural studies on heterobimetallic malonate-bridged MIIReIV complexes (M = Mn, Co, Ni and Cu).

RENIO

QUIMICA INORGANICA

BIBLIOGRAFIA NACIONAL QUIMICA

2010

The mononuclear Re(IV) compound of formula (PPh4)2[ReBr4(mal)] (1) was used as a ligand to obtain the heterobimetallic species [ReBr4(m-mal)Co(dmphen)2]· MeCN (2), [ReBr4(m-mal)Ni(dmphen)2] (3), [ReBr4(m-mal)Mn(dmphen)2] (4a), [ReBr4(m-mal)Mn(dmphen)(H2O)2]·dmphen·MeCN·H2O (4b), [ReBr4(m-mal)Cu(phen)2]·1/4H2O (5) and [ReBr4(m-mal)Cu(bipy)2] (6) (mal = malonate dianion, dmphen = 2,9-dimethyl-1,10-phenanthroline, phen = 1,10-phenanthroline and bipy = 2,2¢-bipyridine). The structures of 2 and 5 (single-crystal X-ray diffraction) are made up of neutral [ReBr4(m-mal)M(AA)] dinuclear units [AA = dmphen with M = Co (2) andAA= phen with M = Cu (5)] where the metal ions are connected through a malonate ligand which exhibits simultaneously the bidentate [at the Re(IV)] and monodentate [at the M(II)] coordination modes. The carboxylate-malonate group in them adopts the anti-syn conformation with intramolecular Re ◊ ◊ ◊M separation of 5.098(8) (2) and 4.947(2)A˚ (5). The magnetic properties of 1–6 were investigated in the temperature range 1.9–295 K. The magnetic behaviour of 1 is the expected for a magnetically isolated Re(IV) complex with a large value of the zero-field splitting (2D ca. -70 cm-1) whereas weak antiferromagnetic interactions between Re(IV) and M(II) are observed in the heterobimetallic compounds 2 (J = -0.63 cm-1), 3 (J = -1.37 cm-1), 4a (J = -1.29 cm-1), 5 (J = -1.83 cm-1) and 6 (J = -0.26 cm-1). Remarkably, 4b behaves as a ferrimagnetic chain with regular alternating Re(IV) andMn(II) cations (J = -2.64 cm-1).

Dalton Transactions v. 39, 2010.-- p. 11403-11411

The Royal Society of Chemistry

2010

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DOI: 10.1039/c0dt00879f

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