Variable coordination of carbazolyl-bis(tetrazole) ligands in lanthanide chemistry

摘要: The synthesis of the protioligand 1,8-bis(2′-isopropyltetrazo-5′-yl)-3,6-di-tert-butylcarbazole, HCzTiPr2, is described. acid–base reaction 2 with various Ln[N(SiMe3)2]3 (Ln = Ce, Sm, Er, Yb, Y) precursors leads to products displaying a variety different bonding modes for CzTiPr− ligand as revealed by X-ray crystallographic studies. smaller lanthanides form Ln(CzTiPr)[N(SiMe3)2]2 complexes Er (3), Yb(4)) near planar, tridentate coordination mode ligand. In contrast, larger Ln(CzTiPr)2[N(SiMe3)2] Ce (5), Sm (6)) at room temperature that feature sandwich structure highly distorted where tetrazole canting allows metal sit well out carbazole plane. Attempts force additional ligands onto or Yb elevated results in isolation trace siloxide Ln(CzTiPr)2(OSiMe3) (3a), (4a)) adopt flat similar 3 and 4. Surprisingly, high Y[N(SiMe3)2]3 affords Y(CzTiPr)3, 7, featuring two one bidentate CzTiPr ligands. Partial hydrolysis 6 occurs over time produce hydroxo-bridged dimer also features bridging ligand, Sm(κ3-CzTiPr)(κ3-μ-CzTiPr)(μ-OH)2Sm(κ3-CzTiPr)(κ2-CzTiPr), 6a, further illustrating remarkable coordinative flexibility system.