COBALT COMPLEXES WITH THE LAMINO)ETHYL]-2,3,4,5-TETRAMETHYLCYCLO-PENTADIENYL LIGAND

Some new Co(I), Co(II), and Co(III) complexes containing the lamino)-e thyl]-2,3,4,5-tetramethylcyclopentadienyl ligand (Cp(AND)) are describ ed. Dicobalt octacarbonyl reacts with Cp(AND)H to give yl]-2,3,4,5-tet ramethyl-cyclopentadienyl)cobalt(I) (Cp(AND)CO(CO)2) With a noncoordin ating dimethylamino function. Addition of iodine to Cp(AND)CO(CO)2 lea ds to the formation of the diiodocyclopentadienylcobalt complex CP(AND )CoI2 with intramolecular dimethylamino coordination. Cp(AND)CoI2 is f ormed via the diiodocarbonylcyclopentadienylcobalt complex Cp(AND)CO(C O)I2. Under ordinary conditions Cp(AND)CoI2 and CP(AND)CO(CO)I2 can ea sily be interconverted. Cp(AND)CoI2 does not react with ethylene. Redu ction of Cp(AND)CoI2 With sodium amalgam under a CO atmosphere yields Cp(AND)CO(CO)2; under an ethylene atmosphere Cp(AND)CO(C2H4)2 with a n oncoordinating dimethylamino group is formed. CP(AND)CO(C2H4)2 can als o be synthesized by a different route: Reaction of CoCl2 with Cp(AND)L i yields the paramagnetic Co(II) dimer [Cp(AND)CoCl]2, which is subseq uently reduced with sodium amalgam to Cp(AND)CO(C2H4)2. Structure inve stigations on Cp(AND)CoI2 confirm the intramolecular coordination of t he dimethylamino group (crystal system: triclinic; space group P1BAR; a = 7.903(3) angstrom, b = 12.802(7) angstrom, c = 14.067(5) angstrom, alpha = 106.94(4)-degrees, beta = 92.12(3)-degrees, gamma = 107.55(4) -degrees; Z = 2).