Inorganic Chemistry, Vol.42, No.1, 180-186, 2003
Synthesis, structure, and magnetic properties of [Mn-III(salpn)NCS](n), a helical polymer, and the dimer [Mn-III(salpn)NCS](2). Weak ferromagnetism in [Mn-III(salpn)NCS](n) related to the strong magnetic anisotropy in Jahn-Teller Mn(III) (salpnH(2) N,N'-bis(salicylidene)-1,3-diaminopropane)
Dimeric [Mn(salpn)NCS](2) (1) and polymeric [Mn(salpn)NCS], (2) are,formed by the reaction of Mn(CH3CO2)(2).4H(2)O, the schiff base, and thiocyanate. The formation of the two polymorphic forms is solvent and temperature dependent. 1: orthorhombic, space group Pbca, with a = 12.573(2) Angstrom, b = 13.970(7) Angstrom, c = 18.891(9) Angstrom, and Z = 8. 2: orthorhombic, space group Pna2(1), with a = 12.5277(14) Angstrom, b = 11.576(2) Angstrom, c = 11.513(2) Angstrom, and Z = 4. The dimers in 1 are held together by weak noncovalent S...pi (phenyl) interactions leading to a chain along the a-axis. Each monomeric unit of the polymer in 2 is related to its adjacent ones by a 2-fold screw axis leading to a helix along the c-axis. The exchange coupling is nondetectable in the dinner. The magnetic susceptibility of the helical chain fits a classical chain law with J = -3.2 cm(-1) and shows a weak ferromagnetic ordering below 7 K due to spin canting effects.