Band 238, Heft 11-12

The crystal structure of cobalt-bearing adamite (Zn, Co) 2 AsO 4 OH (so-called cobalton adamite) from Mine du Pradet, Cap Garonne, France has been refined from single crystal X-ray diffraction data: Pnnm , a = 831.39(4), b = 852.67(6), c = 605.84(6) pm, w R = 0.0568, 901 F 2 values, 48 variables. The composition of the single crystal and the bulk sample with EDX and ICP-OES was determined as Zn 1.94 Co 0.06 (AsO 4 )OH and (Co 0.085 Ni 0.037 Cu 0.270 Zn 1.608 )AsO 4 OH. The Co 2+ , Ni 2+ and Cu 2+ incorporation in the bulk sample leads to Curie paramagnetism with an experimental moment of 2.85 µ B / M 2+ cation and explains the pink color along with the greenish edges. The Raman spectrum shows the characteristic vibrations of the AsO 4 tetrahedra and the M O 5 pyramids as well as the O–H stretching mode. The adamite structure is closely related with the olivenite type (space group P 2 1 / n 11). This structural relationship is discussed on the basis of a group–subgroup scheme (Bärnighausen formalism).

The six new trinuclear fluorocarboxylates with tetrahydrofuran (THF) molecules as terminal ligands are presented. The structures of compounds have been determined by single-crystal X-ray diffraction. According to the structure data, complexes of nickel (II) and cobalt (II) form isomorphous series, namely [K(CF 3 COOH) 6 ][M 3 (μ 3 -F)(CF 3 COO) 6 (THF) 3 ] (M = Co ( I ) and Ni ( II )), Na[M 3 (μ 3 -F)(CF 3 COO) 6 (THF)(CF 3 COOH) 2 ] (M = Co ( III ) and Ni ( IV )) and [Li(CF 3 COOH) 4 ][M 3 (μ 3 -F)(CF 3 COO) 6 (THF) 3 ] (M = Co ( V ) and Ni ( VI )). In crystal structures of I , II , V and VI , previously unknown cations [K(CF 3 COOH) 6 ] + and [Li(CF 3 COOH) 4 ] + have been detected. All substances were studied by IR spectroscopy, and bands sensitive to the nature of metal atoms included in the compounds have been found. The inverse coordination of tridentate fluoride-ion in cobalt (II) and nickel (II) fluorocarboxylates is discussed in the article.

Pseudopeptides are a versatile class of organic building blocks having potential applications in a wide range of domains. In the current study, N and C termini protected l -alanine based short pseudopeptide was synthesized, where 5-aminoisophthalic acid (5-AIA), a rigid non-proteogenic γ-amino butyric acid was incorporated as C-terminal residue. The single crystal X-ray analysis revealed that the l -Ala residue of the aforesaid peptide adopts ϕ and ψ values characteristic of polyproline II conformation. Self-assembly of the pseudopeptide seems to represent a supramolecular helical architecture via NH⋯O, CH⋯O hydrogen bonding and π–π interactions.