C45H35LaO7, trigonal, R3 (no. 146), a = 22.3832(11) Å, c = 6.4522(3) Å, V = 2799.5(3) Å3, Z = 3, Rgt(F) = 0.0192, wRref(F2) = 0.0462, T = 200 K.

Source of materialThecompound was obtained upon reacting copper(II)sulfate with 1,10-phenanthroline and oxalic acid in asolution of sodium hydroxide in amixture of water and acetone. Crystals suitable for the X-ray diffraction study were obtained upon storage of the reaction batch at 0°C. ExperimentaldetailsCarbon-bound Hatomswere placed in calculated positions (C-H 0.95 Å) and were included in the refinementinthe riding model approximation, with U iso (H) setto1.2U eq (C). The Hatoms of the watermolecules were locatedonadifferenceFourier mapand refined freely. DiscussionHomoleptic and heteroleptic coordination compounds of copper(II) and oxalic acid have been known to chemists for decades. Due to the versatile nature of oxalic acid in termsofdonor action, several coordination modes have been described for it, resulting in the formation of either monomeric, dinuclear or polymeric coordination compounds. For heteroleptic examples featuring 1,10-phenanthroline as the auxiliary ligand, all three coordination modes of oxalic acid have been secured on grounds of structural analyses conducted on single crystals: monomeric [1][2][3][4][5],dimeric [6,7] and polymeric [8],the latter one employing the oxalate anion as chelating, tetradentate ligand. In the wake of acomprehensive study about simple heteroleptic copper(II) coordination compounds with chelating ligands, anew coordination mode for the system 1,10-phenanthroline, oxalic acid and copper(II) was found. The title compound is achain-type coordination polymer featuring copper(II) as the central atoms. The asymmetricu nit containshalfamolecule of the repetition unitaswell as twomolecules of water. Thecoordination sphere around the copper atomis composed by one chelating molecule of 1,10-phenanthroline as wellastwo monodentate oxalate anions.The carbonyl-typeoxygen atomso ft he latter two formally extend the coordination sphere around the central atomt oadistorted octahedron. Each oxalate,therefore, actsasamonodentate bridging ligandwhich is different fromthe other coordination mode thathas been reported earlier [8]. The Cu-Nbond lengths are measured at 2.0071(13) Å which is in good agreement witht he corresponding values reportedf or others imilar compounds derived fromc opper(II), 1,10-phenanthroline and oxalicacid whose metricalparameters havebeendeposited withthe Cambridge Structural Database [9]. The Cu-Obonds involving the anionicoxygen atomare found at 1.9907(10) Åwhich is slightlylongerthan the most common values reported [9].The Cu-Obonds directed towards the carbonyl oxygen atom are measured at 2.2935(10)Å .Ac onformational analysis of the chelate rings according to Cremer&Pople [10] is precludedbythe smallpuckering amplitudes in both cases(t= 0.2°for the ringstemming from1,10-phenanthroline and t =2.0°f or the ring stemming from oxalic acid, involving the coordinating carbonyl-typeoxygen atom).Inthe crystal, classicalhydrogen bonds of the O-H×××Ot ype are observed next to C-H×××O contacts whose range invariably falls below the sum of van-derWaals radii of...

Source of materialThec ompoundw as prepared upon reacting copper(II) acetate with 1,10-phenanthroline in am ixture of aqueous sodium hydroxide and acetone. Crystals suitable for the diffraction study evolved upon prolonged storage of the reaction vessel at ambient conditions with contact to air. Experimental detailsCarbon-bound Hatomswere placed in calculated positions (C-H 0.95 Å) and were included in the refinementinthe riding model approximation, with U iso (H) setto1.2U eq (C). All oxygen-bound Ha toms were locatedo nad ifferenceF ourier mapa nd refined freely. DiscussionCoordination compounds of copper show abroad variation in colour over the range from blue to green in aqueous solution. In the solid state,t he colours often seem to deviate substantially. The latter can be rationalized in terms of changing coordination spheres upon the transition from the dissolved into the solid state as well as by simply assuming concentration effects -i.e. intensification of thec olouru ponc rystallization from solution.Aresearch project was designed to elucidate the rules that influence on theabsorptionspectra of transition metal coordination compounds that -onabroader scale -will allow for the quantification of the simple qualitative crystal field and molecular orbital description of d-d transitions and, ultimately, the tailoring of compounds with definedU V/Viss pectra. As metrical parameters play ak ey role in this context, bond lengths and distances between the respective central atomsand their bonding partners are to be determined by means of single-crystal diffraction studies. At the beginning of the project, simple compounds of copper(II) were chosen as astarting point, among others, the title compound.

C5H7O3F3, monoclinic, P21/c, a = 7.9450(4) Å, b = 21.0079(10) Å, c = 8.5285(3), β = 101.240(2)°, V = 1396.17(11) Å3, Z = 8, Rgt(F) = 0.0374, wRref(F2) = 0.1005, T = 200.