AMINO ACID-LANTHANIDE INTERACTIONS .2. THE X-RAY CRYSTAL-STRUCTURES OF LANTHANIDE AND CALCIUM COMPLEXES OF 1-AMINO CYCLOHEXANE-1-CARBOXYLICACID (ACC(6)), ACC(6))(4)(H2O)(8)](CLO4)(6)CENTER-DOT(H2O)(11)(2) ANDCC(6))(12)(H2O)(6)](CLO4)(10)CENTER-DOT(H2O)(4)(3)

The structures of [Nd-2(Acc(6))(H2O)(6)](ClO4)(6) .(H2O)(6) (1) [Er-2( Acc(6))(4)(H2O)(8)](ClO4)(6) .(H2O)(11) (2) and [Ca-5(Acc(6))(12)(H2O) (6)](ClO4)(10).(H2O)(4) (3) (Acc(6) = 1-aminocyclohexane-1-carboxylic acid) have been determined by X-ray crystallography. The lanthanide co mplexes 1 and 2 are dimeric in which two lanthanide cations are bridge d by four carboxylato groups of Acc(6) molecules. In addition, the neo dymium complex (1) features the unidentate coordination of the carboxy l group of an Acc(6) molecule in place of a water molecule in the erbi um complex (2). The coordination number in both 1 and 2 is eight. The calcium Acc(6) complex (3) is polymeric; three different calcium envir onments are observed in the asymmetric unit. Two calcium ions are hexa -coordinated and one is hepta-coordinated. Considerable differences ar e observed between the solid state structures of Ln(III) and Ca-II com plexes of Acc(6). Copyright (C) 1996 Elsevier Science Ltd