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Two new layered silicates, La4Mn5Si4022 and La4V5Si4022, have been prepared and their structures determined. La4MnsSi4022 and La4V5Si4022 crystallize in the monoclinic space group C2/m\ a = 14.024(2), b = 5.571(2), c = 11.703(2) A, j3 = 114.34(4)°withZ = 2 formula units per cell and a = 13.510(3), b = 5.605(1), c = 11.114(2) A, j3 = 100.45(3)°with Z = 2 formula units per cell, respectively. The structures were determined by single-crystal X-ray diffraction and refined to residuals of R = 2.73% and 3.82%, respectively. The manganese compound crystallizes in the perrierite structure while the vanadium compound crystallizes in the related chevkinite structure. Both perrierite and chevkinite display nearly eclipsed sorosilicate groups which separate rutile-like sheets of edge-shared transition metal-oxygen octahedra from single, isolated transition metal-oxygen octahedra. Metal-metal distances within the rutile-like sheet are on the order of 2.8 A in both compounds, approximately Rc, the critical metal-metal distance defined by Goodenough for appreciable metal-metal interactions and electronic delocalization. Preliminary magnetic data are also presented.

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