Organometallic complexes, ligand metal interaction

Second and more importantly, the ligand metal interaction in organometallic complexes involves only certain orbitals on both the ligand and the metal. The electronic states giving rise to shifts in an NMR e qperiment may not involve these orbitals. 

Chiefly through the work of Jonas and co-workers ( ) mixed-metal organometallic complexes also are known that involve interactions of lithium atoms with unsaturated r-bonded hydrocarbon ligands (olefin, cyclopentadienyl, arene, etc.). While reviews already are available 88, S9), we include examples for comparison purposes. The lithium complexes in this section show increasing complexity and diversity both in the geometries around the lithium atoms and in the degree and type of interactions involved. The common feature in these compounds is the interaction of a lithium atom with a hydrocarbon ligand which is n... 

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