Studies on organolanthanide complexes: VII. Formation and cleavage of carbon-metal bonds of dicyclopentadienyl-early lanthanide complexes

Four new 1,10-phenanthroline-coordinated early lanthanide complexes containing a σ-carbon-metal bond 1–4 were synthesized by the reaction of alkynylsodium or alkyllithium with (η⁵-C₅H₅)₂LnCl·nPhen in THF at 0 or −78°C. The complexes (η⁵-C₅H₅)₂LnCl·nPhen were prepared from LnCl₃·nPhen and C₅H₅Na. 1,1′-Trimethylenedicyclopentadienyl(phenylacetylenylneodymium). THF 5 was also prepared. These complexes were identified by elemental analysis, IR, ¹H NMR spectroscopy and thermogravimetry. Protolysis reactions of these complexes with H₂O. CH₃OH and t-C₄H₉OH show that different protolytic reagents give the products with different cleavage extents of σ- and π-bonds. The ligands in the complexes also affect the cleavage of π-bonds. β-Hydrogen elimination of complex 3 takes place with thermal decomposition.