Identification of coordination polyhedra in crystal structures

Abstract

Coordination polyhedra in crystals are identified by matching interbond angle matrices for observed and ideal polyhedra. An algorithm for permuting the N vertices of the observed polyhedron is described in which not all of the N! combinations are examined. The method has been used to identify a number of higher-coordination polyhedra.

Solvent-Free Lanthanoid Complexes Derived From Chelation-Supported Organoamide Ligands

“…Each of the molecules is monomeric with a sixcoordinate metal centre surrounded by three bidentate L ligands (L ϭ L 1 or L 2 ) with the bulky amido groups arranged in a meridional configuration. The geometry is best described as a distorted octahedron (best-fit polyhedron [32] [27] which has a fac orientation of the bidentate [27] whereas 1e, 2a·(PhMe), 2d and 2e have two similar angles but one larger transoid angle (Table 1). Even with the mer configuration, two of the NSiMe 3 groups are pushed above and below the equatorial plane presumably to reduce steric repulsion from the otherwise closely proximate bulky amides.…”

Dimeric Structure of [(η2-NO3)2(tpy)Bi(μ-OH)2Bi(tpy)(η2-NO3)2]

“…The X-ray structure of this material revealed a hydroxide-bridged dimer [Bi(NO 3 ) 2 (l-OH)( tpy)] 2 , (Figure 1), where the Bi center has nine-coordinate stereochemistry with unsymmetrically bound bidentate nitrate ligands. The geometry about bismuth is best described (polyhedron fitting basis [13]) as being distorted from a doubled trigonal prism (D 3h ), towards a 4,4,4-tricapped trigonal prism. This distortion presumably arises from the very small bite angle imparted by the g 2 -NO 3 ligands.…”

Hydrothermal Synthesis, Structural Determination, and Properties of a New Family of Mononuclear Lanthanide Complexes with Pyridines Bearing More Flexible Pendant-Arm Carboxylate Substituents

“…The europium ion is nine-coordinated by two oxygen atoms [O(1), O(2), O(3)] from three 3-pyrac ligands and three oxygen atoms from three coordinated water molecules and has a distorted tricapped trigonal prismatic coordination polyhedron (Figure 1b). [17] The carboxylates of 3-pyrac ligands all adopt chelating bidentate modes to coordinate with lanthanide ions. The distances between Eu and coordinated oxygen atoms from 3-pyrac ligands are 2.541 (2) (2) 296 (2) 296 (2) 296 (2) 296 (2) 296 (2) 296 (2) Wavelength, Å (3) 18.663 (2) 18.587 (2) 18.550 (3) 18.551 (3) 18.538 (4) 18.533 (2) 18.538 (4) b, Å 18.544 (3) 18.663 (2) 18.587 (2) 18.550 (3) 18.551 (3) 18.538 (4) 18.533 (2) 18.538 (4) c, Å 5.849 (8) 5.973 (4) 5.913 (5) 5.907 (6) 5.890 (0) 5.872 (6) 5.866 (8)…”