title: New rare earth metal complexes with nitrogen-rich ligands: 5,5'-bitetrazolate and 1,3-bis(tetrazol-5-yl)triazenate-on the borderline between coordination and the formation of salt-like compounds.
abstract: From the two nitrogen-rich ligands BT(2-) (BT=5,5'-bitetrazole) and BTT(3-) (BTT=1,3-bis(1H-tetrazol-5-yl)triazene), a series of novel rare earth metal complexes were synthesised. For the BT ligand, a vast number of these complexes could be structurally characterised by single-crystal XRD, revealing structures ranging from discrete molecular aggregates to salt-like compounds. The isomorphous complexes [La2(BT)3]14 H2O (1) and [Ce2(BT)3]14 H2O (2) reveal discrete molecules in which one BT(2-) acts as a bridging ligand and two BT groups as chelating ligands. The complexes, [M(BT)(H2O)7]2[BT] x (x) H2O (3-5), (M=Nd (3), Sm (4), and Eu (5)), are also isomorphous and consist of [M(BT)(H2O)7]+ ions in which only one BT(2-) acts as a chelate ligand for each metal centre. [Tb(H2O)8]2[BT]3 x H2O (6) and [Er(H2O)8](2)[BT](3)x H2O (7) are salt-like compounds that do not exhibit any significant metal-nitrogen contacts. In the BTT-samarium compound 9, discrete molecules were found in which BTT(3-) acts as a tridentate ligand with three Sm--N bonds.
authors.affiliation: Universität zu Köln, Institut für Anorganische Chemie, Greinstrasse 6, 50939 Köln, Germany.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Eulgem
authors.forename: Axel
authors.initials: A
authors.lastname: Klein
authors.forename: Nicola
authors.initials: N
authors.lastname: Maggiarosa
authors.forename: Dieter
authors.initials: D
authors.lastname: Naumann
authors.forename: Roland W H
authors.initials: RW
authors.lastname: Pohl
mesh_terms: D018360:Crystallography, X-Ray; D008024:Ligands; D008674:Metals, Rare Earth / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009584:Nitrogen / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D012492:Salts / Q000138:chemical synthesis / Q000737:chemistry; D013696:Temperature; D013777:Tetrazoles / Q000737:chemistry*; D014227:Triazines / Q000737:chemistry*
chemical_list: C530039:1,3-bis(tetrazol-5-yl)triazenate; D008024:Ligands; D008674:Metals, Rare Earth; D009942:Organometallic Compounds; D012492:Salts; D013777:Tetrazoles; D014227:Triazines; D009584:Nitrogen