title: Transition metal induced derivatisations resulting in novel coordination behaviour of bis(oxamato) ligands.
abstract: Two mononuclear bis(oxamato) complexes with the formula [nBu4N]2[M(2,3-acbo)] (M=Ni (), Cu (), with acbo=anthra-9,10-chinone-2,3-bis(oxamato) have been synthesized starting from symmetric diethyl N,N'-anthra-9,10-chinone-2,3-bis(oxamate) (, 2,3-acboH2Et2). The crystal structures of and have been determined, verifying that the transition metal ions are eta4(kappa2N,kappa2O) coordinated by the [2,3-acbo]4- ligands. Using the asymmetric diethyl N,N'-anthra-9,10-chinone-1,2-bis(oxamate) (, 1,2-acboH2Et2) leads, under otherwise identical reaction conditions, to the novel bis(oxamato) complex [(n)Bu4N]2[Ni(1,2-acbo)] () whereby in the case of Cu(II) the derivate [nBu4N]2[Cu(aibo)2] () (aibo=anthra[1,2-d]-(imidazole-2-carboxylato)-6,11-dione) has been obtained. The crystal structures of and have been determined, displaying that the Ni(II) ion of is eta4(kappa2N,kappa2O) coordinated by the [1,2-acbo]4- ligand. The Cu(II) ion of is coordinated by two [aibo]2- ligands, giving rise to an approximately square-planar trans-bis(aibo-N,O) arrangement. Using the symmetric diethyl N,N'-4,5-dinitro-o-phenylene-bis(oxamate) (, niboH2Et2), possessing strongly electron withdrawing NO2-groups, leads under otherwise identical reaction conditions to the bis(oxamato) complex [nBu4N]2[Ni(nibo)] (), whereby in the case of Cu(II) the derivate [nBu4N]2[Cu(niqo)2] () (niqo=7,8-dinitro-2,3-quinoxalinedionato) has been obtained. The crystal structures of and have been determined, ensuring that the Ni(II) ion of is eta(4)(kappa2N,kappa2O) coordinated by the [nibo]4- ligand. The Cu(II) ion of is coordinated by four oxygen atoms of two [niqo]2- ligands, giving rise to an approximately square-planar coordination geometry.
authors.affiliation: Chemnitz University of Technology, Institute of Chemistry, Strasse der Nationen 62, D-09107, Chemnitz, Germany. tobias.rueffer@chemie.tu-chemnitz.de
authors.forename: Tobias
authors.initials: T
authors.lastname: Rüffer
authors.forename: Björn
authors.initials: B
authors.lastname: Bräuer
authors.forename: François Eya'ane
authors.initials: FE
authors.lastname: Meva
authors.forename: Bernhard
authors.initials: B
authors.lastname: Walfort
mesh_terms: D000873:Anthracenes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D010072:Oxamic Acid / Q000031:analogs & derivatives* / Q000737:chemistry*; D013237:Stereoisomerism; D028561:Transition Elements / Q000737:chemistry*
chemical_list: D000873:Anthracenes; D008024:Ligands; D009942:Organometallic Compounds; D028561:Transition Elements; C532847:diethyl N,N'-anthra-9,10-chinone-2,3-bis(oxamate); D010072:Oxamic Acid