Synthesis, reactions and characterization of seven-coordinate lanthanide (Ln) tetraisopropoxoaluminate complexes [{Ln[ɳ2 -Al(OPri )4 ]2 (PriOH)(µ-Cl)}2 ]

Department of Chemistry, University of Rajasthan, Jaipur-302 004, Rajasthan, India

Manuscript received 04 January 2012, revised 17 April 2014, accepted 21 June 2014

The 1 : 2 reactions between LnCl₃ .PrⁱOH and K{Al(OPrⁱ )₄ } in benzene-isopropyl alcohol, afford novel heptacoordinate lanthanide complexes of the type [(Ln[ɳ² -Al(OPrⁱ )₄ ]₂ (PrⁱOH)(µ-Cl)}₂ ], where Ln = La (1), Nd (2), Gd (3), Ho (4), Yb (5) and Lu (6). Reactions of some of these complexes with an excess of tetrahydrofuran (THF) or pyridine (Py), produce complexes in which coordinated PrⁱOH is replaced by THF or Py. Heating or volatilization of seven-coordinate lanthanide(III) complexes under reduced pressure give six-coordinate complexes, [{Ln[ɳ² -Al(OPrⁱ )₄ ]₂ (µ-Cl)}₂ ]. Unsolvated complexes, when Ln = La or Gd on reactions with two equivalents of KOPrⁱ in benzene medium yield dimeric compounds having Ln(µ-OPrⁱ )₂Ln bridging unit, [{Ln[ɳ² -Al(OPrⁱ )₄ ]₂ (µ-OPrⁱ )}₂ ]. All of these new complexes have been characterized by analysis, ¹H and ¹³C NMR (when Ln = La, Nd, Lu) and IR spectroscopy and ebulioscopic molecular weight measurements.