Transition Metal Derivatives of a ((Dimethylamino)ethyl)cyclopentadienyl Ligand. Synthesis and Structures of Amino-Containing Cyclopentadienyl Derivatives of Cobalt(I) and -(III) Including Water-Soluble Compounds

The synthesis of monometallic cobalt(III) and -(I) complexes of ((dimethylamino)ethyl)cyclopentadienyl are reported. The presence of the basic amino group facilitates these synthesis using the corresponding cyclopentadiene complexes as starting material. A cobaltocenium green complex [{eta(5)-C(5)H(4)(CH(2))(2)N(H)Me(2)}(2)Co(III)](3+)(Cl(-))(3) (3) was obtained from C(5)H(5)(CH(2))(2)NMe(2) (1) or from its salt M[C(5)H(4)(CH(2))(2)NMe(2)] (M = Na, Li) (2) upon reaction with Co(II)Cl(2) in THF. The structure of the complex [{(eta(5)-C(5)H(4)(CH(2))(2)NMe(2))(eta(5)-C(5)H(4)(CH(2))(2)N(H)Me(2))}Co(I)(II)](PF(6))(2) (4), prepared from 3 by treatment with NH(4)PF(6) in aqueous solutions, was solved in the triclinic space group P&onemacr; with one molecule in the unit cell, the dimensions of which were a = 6.314(2) Å, b = 7.137(2) Å, c = 13.452(2) Å, alpha = 103.66(2) degrees, beta = 90.25(2) degrees, gamma = 92.89(2) degrees, and V = 588.2(3) Å(3). Adjacent molecules in the unit cell of 4 are hydrogen bonded via a H(+) through their -NMe(2) side chains. The reaction of Co(2)(CO)(8) with C(5)H(5)(CH(2))(2)NMe(2) (1) leads to the formation of [{eta(5)-C(5)H(4)(CH(2))(2)NMe(2)}Co(I)(CO)(2)] (5). Treatment of 5 with HBF(4) in ether solutions yielded [{eta(5)-C(5)H(4)(CH(2))(2)N(H)Me(2)}Co(I)(CO)(2)](+)BF(4)(-) (6). Oxidation of 5 with I(2) or Cl(2) gas yielded [{eta(5)-C(5)H(4)(CH(2))(2)NMe(2)}Co(III)I(2)] (7a) and [{eta(5)-C(5)H(4)(CH(2))(2)NMe(2)}Co(III)Cl(2)] (7b). Addition of HBF(4) to complex 7a resulted in the breaking of the Co(III)-NMe(2) bond, producing the dimeric complex [{(eta(5)-C(5)H(4)(CH(2))(2)N(H)Me(2))Co(III)I(2)}(2)](2+)(BF(4)(-))(2) (9). The bridged diiodo dimer 10, [{(eta(5)-C(5)H(4)(CH(2))(2)NMe(2))CoI}(2)](2+)(BF(4)(-))(2), on the other hand, could be obtained from complex 7a upon addition of AgBF(4) in CH(2)Cl(2).