title: Low-dimensional coordination polymeric structures in alkali metal complex salts of the herbicide (2,4-dichlorophenoxy)acetic acid (2,4-D).
abstract: The Li, Rb and Cs complexes with the herbicide (2,4-dichlorophenoxy)acetic acid (2,4-D), namely poly[[aqua[μ3-(2,4-dichlorophenoxy)acetato-κ(3)O(1):O(1):O(1')]lithium(I)] dihydrate], {[Li(C8H5Cl2O3)(H2O)]·2H2O}n, (I), poly[μ-aqua-bis[μ3-(2,4-dichlorophenoxy)acetato-κ(4)O(1):O(1'):O(1'),Cl(2)]dirubidium(I)], [Rb2(C8H5Cl2O3)2(H2O)]n, (II), and poly[μ-aqua-bis[μ3-(2,4-dichlorophenoxy)acetato-κ(5)O(1):O(1'):O(1'),O(2),Cl(2)]dicaesium(I)], [Cs2(C8H5Cl2O3)2(H2O)]n, (III), respectively, have been determined and their two-dimensional polymeric structures are described. In (I), the slightly distorted tetrahedral LiO4 coordination involves three carboxylate O-atom donors, of which two are bridging, and a monodentate aqua ligand, together with two water molecules of solvation. Conjoined six-membered ring systems generate a one-dimensional coordination polymeric chain which extends along b and interspecies water O-H...O hydrogen-bonding interactions give the overall two-dimensional layers which lie parallel to (001). In hemihydrate complex (II), the irregular octahedral RbO5Cl coordination about Rb(+) comprises a single bridging water molecule which lies on a twofold rotation axis, a bidentate O(carboxy),Cl-chelate interaction and three bridging carboxylate O-atom bonding interactions from the 2,4-D ligand. A two-dimensional coordination polymeric layer structure lying parallel to (100) is formed through a number of conjoined cyclic bridges, including a centrosymmetric four-membered Rb2O2 ring system with an Rb...Rb separation of 4.3312 (5) Å. The coordinated water molecule forms intralayer aqua-carboxylate O-H...O hydrogen bonds. Complex (III) comprises two crystallographically independent (Z' = 2) irregular CsO6Cl coordination centres, each comprising two O-atom donors (carboxylate and phenoxy) and a ring-substituted Cl-atom donor from the 2,4-D ligand species in a tridentate chelate mode, two O-atom donors from bridging carboxylate groups and one from a bridging water molecule. However, the two 2,4-D ligands are conformationally very dissimilar, with one phenoxyacetate side chain being synclinal and the other being antiperiplanar. The minimum Cs...Cs separation is 4.4463 (5) Å. Structure extension gives coordination polymeric layers which lie parallel to (001) and are stabilized by intralayer water-carboxylate O-H...O hydrogen bonds.
authors: Science and Engineering Faculty, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia.
authors: Graham
authors: G
authors: Smith
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000737:chemistry*; D000468:Alkalies / Q000737:chemistry*; D002264:Carboxylic Acids / Q000737:chemistry; D056831:Coordination Complexes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008024:Ligands; D015394:Molecular Structure; D012492:Salts; D014867:Water / Q000737:chemistry
chemical_list: D000468:Alkalies; D002264:Carboxylic Acids; D056831:Coordination Complexes; D008024:Ligands; D012492:Salts; D014867:Water; D015084:2,4-Dichlorophenoxyacetic Acid
keywords: (2,4-dichlorophenoxy)acetic acid; alkali metal salts; crystal structure; herbicides; low-dimensional coordination polymers