By using Vitamin B6 in its monodeprotonated pyridoxine form (PN-H) [PN = 3-hydroxy-4,5-bis-(hydroxymethyl)-2-methylpyridine], two tetranuclear compoundsof formula [Mn4(PN H)4(CH3CO2)3Cl2]Cl·2CH3OH·2H2O (1) and [Cu4(PN-H)4Cl2(H2O)2]Cl2 (2) have been synthesized and magneto-structurally characterized. 1 crystallizes in the triclinicsystem with space group P1̅ whereas 2 crystallizes in theorthorhombic system with Fdd2 as space group. They exhibitMnII2MnIII2 (1) and CuII4 (2) cubane cores containing four monodeprotonated pyridoxine groups simultaneously acting aschelating and bridging ligands (1 and 2), three bridging acetate ligands in the syn-syn conformation (1), and two terminally bound chloride anions (1 and 2) plus two coordinated water molecules(2). The electroneutrality is achieved by the presence of chloride counterions in both compounds. Tri- [Mn(1) and Mn(3)] and divalent [Mn(2) and Mn(4)] manganese centers coexist in 1, all being six-coordinate with distorted Mn(1/3)O6 and Mn(2/4)O5Cl octahedral surroundings, respectively, the equatorial Mn−O bonds being about 0.2 Å shorter at the former ones. Thetwo crystallographically independent copper(II) ions in 2 are five-coordinate in somewhat distorted CuO5 [Cu(1)] and CuO4Cl[Cu(2)] square pyramidal geometries. The values of the intracore metal−metal separation cover the ranges 3.144(1)−3.535(1)(1) and 2.922(6)−3.376(1) Å (2). The magnetic properties of 1 and 2 were investigated in the temperature range 1.9−300 K, and they correspond to an overall antiferromagnetic behavior with susceptibility maxima at 5.0 (1) and 65.0 K (2). The analysis of the magnetic susceptibility data showed the coexistence of intracore antiferro- and ferromagnetic interactions in the twocompounds. Their values compare well with those existing in the literature for the parent systems.
By using Vitamin B6 in its monodeprotonated pyridoxine form (PN-H) [PN = 3-hydroxy-4,5-bis-(hydroxymethyl)-2-methylpyridine], two tetranuclear compounds of formula [Mn4(PN-H)4(CH3CO2)3Cl2]Cl·2CH3OH·2H2O (1)and [Cu4(PN-H)4Cl2(H2O)2]Cl2 (2) have been synthesized andmagneto-structurally characterized. 1 crystallizes in the triclinic system with space group P1̅ whereas 2 crystallizes in the orthorhombic system with Fdd2 as space group. They exhibitMn(II)2Mn(III)2 (1) and Cu(II)4 (2) cubane cores containing four monodeprotonated pyridoxine groups simultaneously acting aschelating and bridging ligands (1 and 2), three bridging acetate ligands in the syn-syn conformation (1), and two terminally boundchloride anions (1 and 2) plus two coordinated water molecules (2). The electroneutrality is achieved by the presence of chloride counterions in both compounds. Tri- [Mn(1) and Mn(3)] and divalent [Mn(2) and Mn(4)] manganese centers coexist in 1, all being six-coordinate with distorted Mn(1/3)O6 and Mn(2/4)O5Cl octahedral surroundings, respectively, the equatorial Mn−O bonds being about 0.2 Å shorter at the former ones. The two crystallographically independent copper(II) ions in 2 are five-coordinate in somewhat distorted CuO5 [Cu(1)] and CuO4Cl [Cu(2)] square pyramidal geometries. The values of the intracore metal−metal separation cover the ranges 3.144(1)−3.535(1)(1) and 2.922(6)−3.376(1) Å (2). The magnetic properties of 1 and 2 were investigated in the temperature range 1.9−300 K, and they correspond to an overall antiferromagnetic behavior with susceptibility maxima at 5.0 (1) and 65.0 K (2). The analysis of the magnetic susceptibility data showed the coexistence of intracore antiferro- and ferromagnetic interactions in the twocompounds. Their values compare well with those existing in the literature for the parent systems.
Cubane-Type Cu(II)4 and Mn(II)2Mn(III)2 Complexes Based on Pyridoxine: A Versatile Ligand for Metal Assembling
Marino N;ARMENTANO, Donatella
;Mastropietro T. F;DE MUNNO, Giovanni;
2013-01-01
Abstract
By using Vitamin B6 in its monodeprotonated pyridoxine form (PN-H) [PN = 3-hydroxy-4,5-bis-(hydroxymethyl)-2-methylpyridine], two tetranuclear compoundsof formula [Mn4(PN H)4(CH3CO2)3Cl2]Cl·2CH3OH·2H2O (1) and [Cu4(PN-H)4Cl2(H2O)2]Cl2 (2) have been synthesized and magneto-structurally characterized. 1 crystallizes in the triclinicsystem with space group P1̅ whereas 2 crystallizes in theorthorhombic system with Fdd2 as space group. They exhibitMnII2MnIII2 (1) and CuII4 (2) cubane cores containing four monodeprotonated pyridoxine groups simultaneously acting aschelating and bridging ligands (1 and 2), three bridging acetate ligands in the syn-syn conformation (1), and two terminally bound chloride anions (1 and 2) plus two coordinated water molecules(2). The electroneutrality is achieved by the presence of chloride counterions in both compounds. Tri- [Mn(1) and Mn(3)] and divalent [Mn(2) and Mn(4)] manganese centers coexist in 1, all being six-coordinate with distorted Mn(1/3)O6 and Mn(2/4)O5Cl octahedral surroundings, respectively, the equatorial Mn−O bonds being about 0.2 Å shorter at the former ones. Thetwo crystallographically independent copper(II) ions in 2 are five-coordinate in somewhat distorted CuO5 [Cu(1)] and CuO4Cl[Cu(2)] square pyramidal geometries. The values of the intracore metal−metal separation cover the ranges 3.144(1)−3.535(1)(1) and 2.922(6)−3.376(1) Å (2). The magnetic properties of 1 and 2 were investigated in the temperature range 1.9−300 K, and they correspond to an overall antiferromagnetic behavior with susceptibility maxima at 5.0 (1) and 65.0 K (2). The analysis of the magnetic susceptibility data showed the coexistence of intracore antiferro- and ferromagnetic interactions in the twocompounds. Their values compare well with those existing in the literature for the parent systems.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
