Coexistence of long-range ferromagnetic ordering and spin-glass behavior observed in the first inorganic–organic hybrid 1-D oxalate-bridging nona-MnII sandwiched tungstoantimonate chain

Abstract

A neoteric 1-D sinusoidal tungstoantimonate (TA) Na₂H₄{[Mn(H₂O)₃]₃[Mn(H₂O)₂]₂[Mn(H₂O)][Mn(C₂O₄)]₃[B-α-SbW₉O₃₃]₂}·31H₂O (1) was synthesized from the reaction of Na₉[B-α-SbW₉O₃₃]·19.5H₂O with MnCl₂·4H₂O with the assistance of oxalic acid and structurally characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction, powder X-ray diffraction and thermal analyses. In 1, an unprecedented oxalate-bridging nona-Mn^II {[Mn(H₂O)₃]₃[Mn(H₂O)₂]₂[Mn(H₂O)][Mn(C₂O₄)]₃}¹²⁺ cluster is clamped by two trivacant Keggin [B-α-SbW₉O₃₃]⁹⁻ fragments forming a unique nona-Mn^II-encapsulated sandwich-type species. In the sandwich belt, the internal hexa-Mn^II {[Mn(H₂O)₂]₂[Mn(H₂O)][Mn(C₂O₄)]₃}⁶⁺ ring is alternately concatenated with three [Mn(H₂O)₃]²⁺ ions situated at three vertices of an equicrural triangle through oxalate linkers, completing an approximately coplanar nona-Mn^II core. More interestingly, adjacent nona-Mn^II-sandwiched TA units are interconnected by double Mn^II–C₂O₄ linkages, giving rise to the first inorganic–organic hybrid 1-D chain high-nuclear Mn-sandwiched TA. Furthermore, the zero-field-cooling/field-cooled magnetization and alternating current magnetic susceptibility measurements reveal the occurrence of long-range ferromagnetic ordering and spin-glass behavior in 1, which are further consolidated by the fitting of the Arrhenius law and the conventional critical scaling law of spin dynamics.