The chemistry and the stereochemistry of poly(N-alkyliminoalanes)

Lewis-base adducts of Group 1B metal(I) compounds. Part 19. Crystal structures of bis(1,10-phenanthroline)copper(I) perchlorate and dibromocuprate(I)

“…The anion of (2) is novel, and has only very recently been reported for the first time; all atoms lie on the 2 axis, so that it is truly linear. Cu-Br(l,2) are 2.209(2), 2.223 (2) (Table 3), comparable with the value reported for the tetrabutylammonium salt In each structure the cation lies with the copper atom on a 2 axis; the dispositions of the ligands in relation to the symmetry axes differ, however. Ideally, it might be expected that the [Cu-(phen),] + species should approach its maximum possible sym- Transformations of the asymmetric unit: i X, y , 4 -2, I 1x , y , $ -2 .…”

“…R was 0.056 for 709 independent 'observed' reflections. Crystals of (2) are monoclinic, C2/c, a = 17.206 (4), b = 13.365 (2), c = 10.920(3) A, p = 11 5.43(2)", Z = 4. R was 0.048 for 1 091 independent 'observed' reflections.…”

Lanthanide(III)/Actinide(III) Differentiation in the Cerium and Uranium Complexes [M(C5Me5)2(L)]0,+ (L=2,2′‐Bipyridine, 2,2′:6′,2′′‐Terpyridine): Structural, Magnetic, and Reactivity Studies

“…However, the three U1ÀN distances are quite identical, as found in 3 b. The U2ÀI1 and U2ÀI2 distances, with a mean value of 3.1038 (14) , are at the lower limit of the range of uranium(iii)-iodide distances, which range from 3.103(2) in [UI 3 (thf) 4 ] [30] to 3.273(1) in [UI 2 -(terpy) 2 (py)]I·2 py. [4] However, these distances are larger than the uranium(iv)-iodide distances, which are typically 3.0 .…”

“…In addition to their structural and physicochemical properties, such species are attractive for their reactivity, since they are considered to be synthetic equivalents of low-valent species. [13] Such 5f element complexes with azine ligands seem to have been neglected since the reports of the uranium bipyridine compounds [U(bipy) 4 ] [14] and [U(COT)(Cp*)(Me 2 bipy)] (COT = h-C 8 H 8 , Me 2 bipy = 4,4'-dimethyl-2,2'-bipyridine), [15] in which the metal oxidation state is questionable. Following our studies on the differentiation of trivalent lanthanide and uranium ions, especially those concerning the coordination of azine molecules to tris(cyclopentadienyl) complexes of cerium and uranium [16,17] and the selective complexation of uranium(iii) over lanthanide(iii) triflates or iodides by bipy, [3] phen [18] and terpy, [4][5][6] we speculated that the distinct electronic behavior of the 4f and 5f ions, in particular the easier oxidation and better p-donating ability of the actinide, should emerge and lead to significant differences in the structures and reactions of the electron-rich complexes [Ce(Cp*) 2 …”

Square-prismatic vs. square-antiprismatic coordination in complexes of lead(II) with a simple bidentate chelating ligand; effects of intermolecular hydrogen bonding

“…Instead, compressed square-prismatic structures arise with the bidentate chelating ligands lying along the four shorter edges, linking the two square planes. [10][11][12][13] Most of these examples have a lanthanide or actinide ion as the central metal, consistent with the requirement for f-orbital participation. 3 We describe here two eight-coordinate complexes of lead(ii) with the bidentate chelating ligand 3-(2-pyridyl)pyrazole (L), of which one is square prismatic and the other is skewed towards a square-antiprismatic geometry.…”