Synthesis and crystal structure of a complex between lanthanum nitrate and a bicyclic polyether

Abstract

Reaction between lanthanum nitrate hexahydrate and a macrobicyclic polyether in ethanol has yielded a product of overall stoichiometry 3:2. The ligand, 21R, 26S, 29R, 34S-21, 22, 23, 24, 25, 26, 29, 30, 31,32,33, 34-dodecahydro-1,4,7,14,17,20,28,35-octaoxa (2 3,29 syn2 18,34 syn) (7.7) orthocyclophane, L, provides 8 oxygen donor atoms. Crystals were obtained from MeOH/EtOH (50/50). Crystal structure determination on 9590 observations, R=0.059, has shown the triclinic unit cell, a = 26.562(6), b = 13.486(3), c = 12.154(3) Å, α=63.9(1), β = 100.0(1), γ = 102.0(1)° space group P 1 , V = 3806 Å to contain, as the asymmetric unit, two complex cations (La(NO 3) 2L) + and one complex anion (La- (NO 3) 5MeOH) 2−. The lanthanum is 11-coordinated in the anion and one of the cations, in which there is one bidentate and one monodentate nitrate anion and 12-coordinated in the other cation. For the monodentate nitrate LaO = 2.448(9) Å, all other nitrate ions are bidentate (LaO = 2.594(9)−2.743(10) Å). Most LaO bonds are shorter in the 11 than in the 12-coordinated cation. There are large differences in LaO bond lengths according to the nature of the carbon atoms to which the oxygen is attached. The methanol molecule forms a hydrogen bond to one oxygen atom of the monodentate nitrate group.