ON THE REACTION OF MACROCYCLES WITH LANTHANOIDS .2. THE CRYSTAL-STRUCTURES OF [K(THF)3]2[(C22H28N4)2SM2].4THF AND [(C22H22N4)CO].DME

In a complicated redox reaction [(TMTAA)K2] and [SmI2(thf)2] form the polynuclear metal complex [K(thf)3]2[(TMTAT)2Sm2]. This complex crystallizes with four molecules THF per formula unit and its structure was determined by single crystal X-ray investigation (spacegroup P2(1)/c (No. 14), z = 4, a = 998.0(2) pm, b = 2618.3(6) pm, c = 1619.4(3) pm, beta = 96.52(2)-degrees). In the dimeric unit [(TMTAT)2Sm2]2- the Sm3+ ions are bonded to the four N atoms of the macrocyclic ligand and one C6H4 ring of the second ligand is attached eta6 like to one metal ion. Additionally two [K(thf)3]+ fragments are bonded to this central unit, and therefor coordination number seven results for the K+ ion. [TMTAA]2- is not reduced by [Cp2Co] in a similar reaction. The monomeric paramagnetic complex [(TMTAA)Co] (mu(eff) = 2,76 mu(B)) is formed instead. The structure reveils a square planar coordination of the Co atom by the four N atoms of the TMTAA ligand (spacegroup C2/c (No. 15), z = 4, a = 1945.1(4) pm, b = 1165.6(2) pm, c = 1144.7(2) pm, beta = 116.38(1)-degrees).