Cyclopentadienyl Derivatives and Related Compounds

Structures of Orgaitomagnesium Compounds ns Revealed by X-ra 1 i fruction Studios 

In the compounds with bcn/oannclatcd eyclo-pcntadicnc derivates, there is a clear tendency towards lower hapttcitv due to overcrowding. Thus, bisindenylniagnesiuni (IncNMe, 20 (79J) 

Similar to Ihc situation in 19.8, the haptieiiy to (he organic residue is reduced when polydentate amine ligands are involved. This tendency increases in the series Me(// -Ind)Mg-TMEDA (21). Me(// - luorenyl)Mg TMEDA (22) and 23 which forms an ion triplet PMDTA Mg( 2-Me)Mg-PMDTA (PMDTA = Me2NCH2CH2N(Me)CH2CM NM ) with two pentacoordinatc magnesiums and two separate llnorcnide anions 66 (structures not shown). 

---