The interplay between yttrium and barium or copper trifluoroacetates and n-methyldiethanolamine: Synthesis of a heterometallic Y3Cu trifluoroacetate complex and a homometallic Ba-TFA 1D polymer

摘要

The reactions between [Y(TFA)(3)(H2O)(3)] and either [Cu(TFA)(2)(MeOH)] or [Ba(TFA)(2)](infinity). in the presence of excess N-methyl-diethanolamine (mdeaH(2)) have been investigated in relation with their use as precursors for high Tc superconductors. They afford the heterometallic Y3Cu complex [CuY3(mu(3)-OH)(mu-eta(3):eta(1)-mdeaH)3(mu(3)-eta(3):eta(1):eta(1)-mdeaH)(2)(eta(2) -TFA)(mu,eta(2)-TFA)(2)]-(TFA)(2)(H2O) (1) and the homometallic Ba-TFA 1D polymer [Ba-3(eta(3)-mdeaH(2))(2)(mu-eta(3):eta(1)-mdeaH(2))(2)(eta(1)-TFA)(2)(eta(2)-TFA)(2)(mu(3)-eta 2:eta 2:eta 1-TFA)](1 infinity) (2), respectively, in high yield. These compounds were characterised by X-ray diffraction and FT-IR, ESR (for 1) and NMR (for 2) spectroscopy. Single-crystal Xray diffraction studies show the versatile bonding modes of the trifluoroacetate and N-methyldiethanolamine ligands, with the former acting not only as a terminal (eta(1) and eta(2)) or bridging-chelating (p, 112 and mu(3)-eta(2):eta(2):eta(1)) ligand but also as a counterion, whereas the latter, either protonated or partially deprotonated, binds the metal centres in a chelating (eta(3)) or bridging-chelating (p,113:111 and mu(3)-eta(3):eta(1):eta(1))manner. The triangular Y-3 unit [3.480(6)-3.550(6) angstrom] in the cation of 1 consists of one nine-coordinate and two eight-coordinate Y atoms, the former of which are quite scarce in alkoxide chemistry. The unique feature of the 1D polymeric structure of 2 is the secondary F...cation bond, which has not been observed so far f or TFA ligands. In addition, it is the only example where the Ba atom is linked to monodentate, bidentate and bridging trifluoroacetate ligands simultaneously. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)