MAGNETOSTRUCTURAL CORRELATIONS IN FLUOROMANGANATES(III)

A series of structurally closely related fluoromanganates(III) with ch ain structures [A(2)MnFS(H2O), etc.] and with layered structures (AMnF (4)) have been synthesized and the crystal structures determined for m ost of them. In the trans-chain compounds, [MnF6] octahedra, strongly elongated by the Jahn-Teller effect of the d(4) high-spin configuratio n, are arranged in a ferrodistortive manner, while similar octahedra a re 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 o r 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.