Cyclomer complexes. II. Crystal structure of a 2:1 octahydrate complex of 1,4,7,10-tetraoxacyclododecane with sodium hydroxide

Abstract

van Remoortere, et al.148 mm, 20X reduction, negatives) containing all of the supplementary material for the papers in this issue may be obtained from the Journals

The crystal structure of the complex of 1,4,7,10-tetraoxacyclododecane with copper(II) chloride

“…The nature of the thermal motion in this structure is similar is most respects to other cyclomer complexes (van Boer, Neuman, van Remoortere & Steiner, 1974;North, Steiner, van Remoortere & Boer, 1974). The metal ion has the lowest vibrational amplitudes and exhibits the least anisotropy (Table 2 and Fig.…”

“…2. This structure permits the heterocycle to act as a tetradentate ligand in a fundamentally different manner from that in the complexes where it adopts the C4 conformation (van Boer, Neuman, van Remoortere & Steiner, 1974;North, Steiner, van Remoortere & Boer, 1974); in the latter compounds bonding to the metal occurs through four lonepair orbitals from the same side of the ring (referred to a hypothetical planar conformation), but in the Cs geometry three lone pairs from one side of the ring [O(1), 0(4) and 0(7)] are used, and one lone pair from the opposite side [O(10)]. As Figs.…”

“…The preceding studies in this series have established that the 1,4,7,10-tetraoxacyclododecane ligand chelates the alkali metal ions Na, K, and Rb to form novel eight-coordinate species of 2:1 stoichiometry (van Boer, Neuman & van Remoortere, 1974). In these complexes the [M+(CsHI604)2] units display approximate D4 symmetry and the 12-membered rings adopt a conformation belonging to the subgroup C4.…”

Crown ether complexes of alkaline-earth metal ions. I. Structures of 1,4,7,10-tetraoxacyclododecane (12-crown-4) complexed with calcium, strontium and barium thiocyanates

“…As can be seen from the torsion-angle values listed in Table 5, the 12-crown-4 ring adopts a conformation of approximate C4 symmetry (torsion-angle sequence ag+-g +-ag+-g +-ag+-g +-ag+-g +-) in all three independent subunits of both complexes. This quadrangular [3333] conformation is also the most stable one for cyclododecane itself (Anet, Cheng & Wagner, 1972), and it is the most common one for 12-crown-4 metal-ion complexes, having been observed for complexes with NaC1, NaOH, LiSCN and CaC12 (van Remoortere & Boer, 1974;Boer, Neuman, van Remoortere & Steiner, 1974;Groth, 1981;North et al, 1976). In the case of the anhydrous Ba(SCN) 2 complex (3), the Ba 2+ cation is tenfold coordinated.…”

The sodium perchlorate complex of cis-syn-cis dicyclohexano-24-crown-8 ether. X-ray crystal structure and solution conformations as studied by variable temperature 13C NMR spectroscopy at 125 MHz. An example of eight-coordinate sodium

“…H 2 0 (9) the Na' ion is heptacoordinate with the water molecule providing the extra coordination si t : , and the range of Na-0 distances is from 2.32 to 2.62 A. The only reported instance of eight-coordinate sodium in crown ether chemistry occurs in the 2 : 1 octahydrate complex of 12-crown-4 ether with NaOH (10). In this case the sodium ion forms an eight-coordinated sandwich complex of approximate D, symmetry with the two crown ether rings.…”