Preparation, Structure, and Solid-State Reactivity of Lanthanum Propynoates

Abstract

A comparative study of the complexes La 2 (O 2 CCtCH) 6 (H 2 O) 4 ‚2H 2 O (1) and La 2 (O 2 CCtCH) 6 -(C 10 H 8 N 2 ) 2 (H 2 O) 2 ‚4H 2 O‚2C 10 H 8 N 2 (2) was undertaken to assess the effect of introducing bulky ligands on the solid-state reactivity of metal propynoates. A solid-state polymerization reaction occurred when 1 was exposed to 60 Co γ-rays; complex 2 was found to be stable to 60 Co γ-irradiation. Complexes 1 and 2 have closely-related molecular structures and, as expected, rather different packing arrangements. The crystal structures of 1 (with infinite chains of short acetylene-acetylene contacts) and 2 (containing only a chain of only five short acetylene-acetylene contacts) are consistent with the observed reactivity patterns. The results provide useful insight into the planning of syntheses for radiation-sensitive materials. Crystal data: 1: monoclinic, space group P2 1 /c, a ) 11.126(3), b ) 14.174(4), c) 8.851(3) Å; β ) 99.65(3)°; Z ) 2; R ) 0.027, R w ) 0.037 for 3674 data for which I > 1.96σ-(I). 2: triclinic, space group P1 h, a ) 10.393(3), b ) 13.022(4), c ) 13.413(4) Å; R ) 116.90-(1); β ) 101.03(1); γ ) 103.82(1)°; Z ) 1; R ) 0.025, R w ) 0.024 for 4921 data for which F > 4σ(F).

Tetrakis(μ-2,3-dimethoxybenzoato)bis[(2,2′-bipyridine)(2,3-dimethoxybenzoato)lanthanum(III)]

“…The two pyrindine ring planes are not coplanar, the dihedral angle being 9.9 (3) . The LaÐN bond lengths are comparable with the corresponding values found in the analogous complexes [La 2 (propionato) 6 (2,2 H -bpy) 2 ] (Brodkin et al, 1996) and [La 2 (Cl 3 CCOO) 6 (2,2 H -bpy) 2 ] (Cheng et al, 1994).…”

“…2) [symmetry code: (i) 1 À x, Ày, Àz]. A similar coordination environment has been observed previously for lanthanoid(III) complexes such as [Pr 2 (pivalate) 6 (2,2 H -bpy) 2 ] (Pisarevsky et al, 1995), [La 2 (propionato) 6 (2,2 H -bpy) 2 ] (Brodkin et al, 1996), [Ce 2 (CH 3 COO) 6 (phen) 2 ] (phen is phenanthroline; Panagiotopoulos et al, 1995) and [Sm 2 (PhCOO) 6 (phen) 2 ] (Niu et al, 1999).…”

Synthesis, Structure and Luminescence Properties of Four Novel Terbium2‐Fluorobenzoate Complexes

“…[12] The structure of nine-coordinate complexes is the same as those in Figure 3 (parts a and c) and Figure 4 (part b), where two metal ions are linked together by four carboxylato groups with bidentate-bridging and chelating-bridging modes, and each metal ion is also chelated by one carboxylato group and one 2,2Ј-bpy or phen ligand, such as in [Eu(2,3-DMOBA) 3 ·bpy] 2 (2,3-DMOBA = 2,3-dimethoxybenzoate), [15] [Ln 2 (O 2 CCH 3 ) 6 -(phen) 2 ] (Ln = Ce, Gd), [16] and [La 2 (propionato) 6 (2,2Ј-bpy) 2 ]. [17] Eight-or nine-coordinate complexes are formed depending on the different bridges over the two central metal ions of the four carboxyl groups, namely whether the four carboxylato groups are all in a bidentate-bridging mode or two of them are in a bidentate-bridging mode and the other two in a chelating-bridging mode. The phen or 2,2Ј-bpy molecule coordinates to the metal in conventional chelation through two N atoms to form a five-membered ring.…”

Synthesis, structure and property of serial p-carboxylphenoxyacetate-lanthanide coordination polymers

“…For La2, the metal ions coordinated with six O-acetate oxygen atoms(O13D, O14, O3E, O4F, O10, O11G) from six PBDC ligands and two water molecules form an eightcoordinated La 3+ and the coordination geometry can be described as a distorted bicapped trigonal prism in which O9 and O11G act as the capping atoms. The La-O distances are 0.2350(19)-0.2618 (19) nm which are in the normal range [21] . La1 ions are connected by carboxyl bridges into a 2D La1-layer, and similarly, La2 ions and carboxyl form a La2-layer.…”