SYNTHESIS AND CRYSTAL-STRUCTURE OF GRIGNARD COMPOUNDS C5H5MGCL.O(C2H5)2 AND C5ME5MGCL.O(C2H5)2

Single crystals of CpMgCl . O(C2H5)2 (1) (CP = C5H5) and Cp*MgCl . O(C2H5)2 (II) (CP* = C5Me5) have been prepared. In both compounds the formation of dimeric units is shown by X-ray structure determination. These symmetric dimeric species contain MgCl2Mg bridges with nearly identical Mg-Cl distances (dBAR = 243 pm). The Cp and Cp* fragments are eta5-coordinated to the metal atom. The average Mg-C-distances (dBAR = 239 pm (I); 241 pm (II)) are significantly longer than those in MgCp2 (230 pm) and MgCp2 (235 pm) respectively. The Mg-O distances range between 205 and 208 pm.