[Cr ₄ S(O ₂ CCH ₃ ) ₈ (H ₂ O) ₄ ](BF ₄ ) ₂ ⋅H ₂ O: Ferromagnetically Coupled Cr ₄ S Cluster with Spin 6 Ground State

Abstract

Data on the preparation, structure, and magnetism of the new complex [Cr 4 S(O 2 CCH 3 ) 8 (H 2 O) 4 ](BF 4 ) 2 ⋅H 2 O are presented. The metal-sulfur M 4 S core structure is similar to that found in M 4 S[S 2 As(CH 3 ) 2 ] 6 (where M is cobalt or zinc) compounds and in beryllium basic acetate. However, the six-coordinate metal ions in the new Cr 4 S system distinguish it from these structures. The tetranuclear chromium complex is the first example of a new structural type. Its magnetic spin S = 6 ground state, a striking example of intramolecular ferromagnetic coupling, was determined by variable-temperature magnetic susceptibility measurements. Long-range antiferromagnetic intercluster ordering was found below 170 millikelvin.

Secondary building units, nets and bonding in the chemistry of metal–organic frameworks

“…77). 175 The edges of the triangles and square are capped by carboxylates, eight in total. The remaining edges of the Fe 3 O triangle are bridged by PO 3 R ligands.…”

From single-molecule magnetism to long-range ferromagnetism inHpyr[Fe17O16(OH)Vecchini1, Ryan2, Cranswick3 et al. 2008Phys. Rev. B151100View full textAdd to dashboardCite

“…The large molecular spins in these crystals take the place of the individual magnetic ions in conventional materials. The intermolecular magnetic coupling results from either purely dipolar [6][7][8][9] or mixed dipolar and/or weak superexchange 5,[10][11][12][13] interactions. The former are, in principle, much simpler to understand because magnetic phase transitions driven solely by long-range dipolar interactions can be predicted without involving any adjustable parameters.…”

Equation of state and spin-correlation functions of ultrasmall classical Heisenberg magnets

“…3,4 A common feature of these organic-based molecular magnets is that intermolecular magnetic interactions are extremely weak compared to those within individual molecules, i.e., a bulk sample can be described in terms of independent individual molecular magnets. As examples of molecular magnets with ultrasmall numbers of embedded paramagnetic ions we mention: Two dimer systems, one 5 of V 4ϩ ͑spin Sϭ1/2) and the second consisting of 6 Fe 3ϩ ions ͑spin Sϭ5/2); a nearly equilateral triangular array 7 of V 4ϩ ; a nearly square array 8 of Nd 3ϩ ͑total spin j ϭ9/2); a regular tetrahedron array 9 of Cr 3ϩ ͑spin Sϭ3/2); and a nonregular tetrahedron array 10 of Fe 3ϩ ions. Also noteworthy is the pyrochlore antiferromagnet Tb 2 Ti 2 O 7 , although distinct from the class of organic molecules yet sharing the feature that the Tb 3ϩ ions ͑total spin jϭ6) reside on a network of very weakly coupled tetrahedra.…”