The structural and thermal behavior of all members of the homologous series of neodymium(III) alkanoates, ranging from neodymium(III) butyrate to neodymium(III) eicosanoate are described. Neodymium(III) butyrate monohydrate, Nd(C 3 H 7 COO) 3 ‚H 2 O crystallizes in space group P1 h (No. 2), Z ) 2. The lattice parameters are a ) 9.824(2) Å, b ) 11.974(2) Å, c ) 14.633(2) Å, R ) 86.21(2)°, ) 75.92(2)°, γ ) 77.97(2)°. The crystal structure consists of ionic layers of neodymium ions, separated by bilayers of butyrate anions. In the ionic layers, the neodymium ions are connected by bridging tridentate carboxylate groups to zigzag chains, whereas the chains are connected among themselves by bridging bidentate carboxylate groups. The two crystallographically different neodymium ions are both having coordination number 9, with a geometry close to a monocapped square antiprism. The structure of the higher homologues can be derived from the structure of neodymium butyrate by extending the alkyl chains. These compounds have a lamellar bilayer structure with planes of neodymium(III) ions coordinated to the carboxylate groups and with the alkyl chains in an all-trans conformation. All homologous compounds from neodymium(III) pentanoate to neodymium(III) pentadecanoate display a thermotropic mesophase, which was identified by high-temperature X-ray diffraction as a smectic A phase. For the series from neodymium(III) pentanoate to neodymium(III) undecanoate an additional high viscosity mesophase is present between the crystalline state and the smectic A mesophase.

Anhydrous rare earth tris(cinnamates) [RE(cinn) 3 ] (RE ϭ LaϪLu, Y and Sc and cinnH ϭ trans-cinnamic acid) were prepared by metathesis in water and by direct reaction of the metal with cinnamic acid in a 1,2,4,5-tetramethylbenzene flux at ca. 200°C. X-ray crystal structure determinations and X-ray powder data show that, in the solid state, the larger lanthanoids (LaϪDy) form an isomorphous polymeric series consisting of homoleptic ninecoordinate metal centres bonded to three chelating and bridging tridentate cinnamates. The late RE III cinnamate (RE ϭ Dy, HoϪLu, Y) complexes also form linear one-dimensional polymeric chains with all RE metal atoms being seven-coordinate. The cinna-* Prof. Glen B. Deacon 91 mates are either bound tridentate bridging in a μ-η 2 :η 1 fashion, or μ-η 1 :η 1 syn-syn bidentate bridging. A structural break occurs at dysprosium which has been characterised in both crystallographic forms, and gives solely the late RE form when precipitated at 80°C. Sc III cinnamate was also isolated as an analytically pure precipitate which was, again, found to be anhydrous in nature. A structural change was identified by powder XRD between the late RE III cinnamates and Sc III cinnamate.

Rare‐Earth‐Metal Coordination Polymers: Syntheses and Crystal Structures of Three New Glutarates, [Pr2(Glu)3(H2O)4] · 10.5H2O, [Pr(Glu)(H2O)2]Cl, and [Er(Glu)(GluH)(H2O)2] The new rare‐earth dicarboxylates [Pr2(Glu)3(H2O)4] · 10.5H2O (1), [Pr(Glu)(H2O)2]Cl (2) and [Er(Glu)(GluH)(H2O)2] (3) were obtained from the reactions of glutaric acid with PrCl3·6H2O and Er(OH)3, respectively. The crystal structures were determined by single‐crystal X‐ray diffraction. [Pr2(Glu)3(H2O)4] · 10,5H2O crystallizes in the orthorhombic space group Pnma (no. 62) with a = 871.7(4), b = 3105.0(9), c = 1308.3(9) pm and Z = 4. The crystals of [Pr(Glu)(H2O)2]Cl are monoclinic (I2/a; no. 15) with a = 786.2(1), b = 1527.6(2) c = 801.2(1) pm, β = 99.78(1)° and Z = 4. [Er(Glu)(GluH)(H2O)2] crystallizes in the monoclinic space group P21/a (no. 14) with lattice parameters of a = 882.4(1), b = 1375.3(2), c = 1267.4(2) pm, β = 107.13(1)° and Z = 4. The rare‐earth cations have the coordination numbers 10 (1), 8 + 1 (2) and 9 (3). The individual polyhedra are connected to chains and further to sheets in 1 and 2 and to double chains in 3. Only in the water‐rich compound 1 there are channels that contain crystal water molecules. It, therefore, has a considerably lower density than 2 and 3.

Rare‐Earth‐Metal Coordination Polymers: Synthesis and Crystal Structures of Five New Adipinates, [M2(Adi)3(H2O)4](AdiH2)(H2O)4 (M = La, Nd), [Er(Adi)(H2O)5]Cl(H2O) and [M(Adi)(H2O)5](NO3)(H2O) (M = Gd, Er) The new rare‐earth compounds [M2(Adi)3(H2O)4](AdiH2)(H2O)4 (M = La (1), Nd (2)), [Er(Adi)(H2O)5]Cl(H2O) (3) and [M(Adi)(H2O)5](NO3)(H2O) (M = Gd (4), Er (5)) were obtained from the reaction of adipinic acid with La(OH)3·xH2O, Nd2O3, ErCl3·6H2O, Gd(NO)3·xH2O and Er2O3, respectively. Their crystal structures were determined by single‐crystal X‐ray diffraction. The coordination polymers [M2(Adi)3(H2O)4](AdiH2)(H2O)4 crystallize in the triclinic space group ${\rm P}{\bar 1}$ (no. 2) with a = 875.4(1), b = 1000.4(2), c = 1179.0(2) pm, α = 74.70(1), β = 69.85(1), γ = 86.18(2)° and Z = 1 (crystal data for M = La, (1)). The quasi‐isostructural compounds [Er(Adi)(H2O)5]Cl(H2O) (3) and [M(Adi)(H2O)5](NO3)(H2O) (M = Gd (4), Er (5)) crystallize with monoclinic symmetry, space group C2/c (no. 15) with lattice parameters of a = 1231.5(1), b = 1532.6(1), c = 895.4(1) pm, β = 123.44(1)° and Z = 4 (crystal data for (3)). The rare‐earth cations have the coordination numbers 10 (1, 2) and 9 (3, 4 and 5), respectively. The compounds [M2(Adi)3(H2O)4](AdiH2)(H2O)4 are constructed of infinite chains of edge‐sharig [MO8(H2O)2] polyhedra that are cross‐linked by adipinic acid molecules to form framework structures. In [Er(Adi)(H2O)5]Cl(H2O) (3) and [M(Adi)(H2O)5](NO3)(H2O) (M = Gd (4), Er (5)) the central cations are bridged by adipinic acid molecules in a bidentate‐chelating manner to positively charged zigzag chains. Between these the counter ions and crystal water molecules are incorporated.