title: Structural diversity in the coordination of amidines and guanidines to monovalent metal halides.
abstract: A series of structurally characterised, monovalent metal-halide complexes incorporating neutral amidine and guanidine ligands is reported. N,N'-diphenylbenzamidine reacted with copper(I) chloride to afford the bis-ligand complex [CuCl(PhC[NPh][NHPh])2]2 (1), that exists as a chlorine bridged dimer in the solid state, with a non-symmetrical distribution of NH...Cl interactions within the 'Cu2Cl2' metallacycle. In contrast, only one equivalent of the guanidine, Me2NC[NiPr][NHiPr] (2), is coordinated in the copper(I) iodide complex [CuI(Me2NC[NiPr][NHiPr])]2 (3), which was also isolated as the dimer with bridging halide atoms. The molecular structure of the bicyclic guanidine, 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-alpha]pyrimidine (hppH), is reported, revealing a hydrogen bridged dimer with extensive delocalisation throughout the ligand framework. Coordination of hppH to lithium chloride afforded the dimeric bis-ligand complex [LiCl(hppH)2]2 (4) in which each hppH molecule interacts with a different chlorine atom of the central 'Li2Cl2' core of the molecule via NH...Cl hydrogen bonding. In contrast the 2:1 ligand to metal complex is formed with silver(I) chloride to afford AgCl(hppH)2 (5), a unique example of a monomeric, three-coordinate silver chloride supported by nitrogen-based ligands. The series of mixed ligand complexes [CuX(hppH)(PPh3)]n (6, X = Cl, n= 1; 7, X = Br, n= 2; 8 X = I, n= 2) have also been synthesised and structurally characterised, allowing comparisons of the relative coordinating behaviour of hppH and PPh3 as neutral donors at copper(I) centres to be made.
authors.affiliation: Department of Chemistry, School of Life Sciences, University of Sussex, Falmer, Brighton, UK BN1 9QJ.
authors.forename: Sarah H
authors.initials: SH
authors.lastname: Oakley
authors.forename: Delia B
authors.initials: DB
authors.lastname: Soria
authors.forename: Martyn P
authors.initials: MP
authors.lastname: Coles
authors.forename: Peter B
authors.initials: PB
authors.lastname: Hitchcock
mesh_terms: D000578:Amidines / Q000737:chemistry*; D017605:Bromine Compounds / Q000737:chemistry; D017606:Chlorine Compounds / Q000737:chemistry; D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006146:Guanidines / Q000737:chemistry*; D006860:Hydrogen Bonding; D017613:Iodine Compounds / Q000737:chemistry; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*
chemical_list: D000578:Amidines; D017605:Bromine Compounds; D017606:Chlorine Compounds; D006146:Guanidines; D017613:Iodine Compounds; D008024:Ligands; D009942:Organometallic Compounds; D003300:Copper