MAGNETOSTRUCTURAL CORRELATIONS IN FLUOROMANGANATES(III)

A series of structurally closely related fluoromanganates(III) with chain structures [A(2)MnFS(H2O), etc.] and with layered structures (AMnF(4)) have been synthesized and the crystal structures determined for most of them. In the trans-chain compounds, [MnF6] octahedra, strongly elongated by the Jahn-Teller effect of the d(4) high-spin configuration, are arranged in a ferrodistortive manner, while similar octahedra are arranged in an antiferro-distortive manner in the quadratic layers of the AMnF, structures. Variation of A causes a wide variation in Mn-F-Mn bridge angles. Magnetic exchange energies determined for the 1d or 2d magnetic systems clearly correlate with the bridge angles in both systems. Suggestions regarding the type and relative strengths of the exchange interactions involved are made.