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Abstract: The structures of four new alkaloids isolated from the bark of the rain forest trees Galbulimima belgraveana and Galbulimima baccata have been determined by a combination of NMR spectra and single crystal X-ray crystallography. Two of the alkaloids are simple oxygenated derivatives of himbacine, while the remaining two are based on a novel 7,19-cyclo-himbacine skeleton. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis and crystal structure elucidation of two novel polymeric copper(II) complexes has led us to propose a mechanism for the formation of 2-picolinic acid (pic) from di-2-pyridyl ketone (dpk) and benzoic acid from acetophenone. During studies into the interaction of copper ions with the dpk-acetophenone system, two complexes Na2(NCS)2(H2O)[Cu(pic)2] (1) and Na2(H2O)2[Cu(pic)2(NCS)2] (2) which contain pic coordinated to copper were isolated. The occurrence of (1) and (2) has led us to consider the Baeyer–Villiger rearrangement as a possible mechanism for the formation of (1) and (2). [Copyright &y& Elsevier]

Abstract: The supramolecular interactions of the planar guanidinium cation () with benzenesulphonate (1), -phosphonate (2) and -arsonate (3) anions, and several of their 3- and 4-nitro-substituted derivatives is reported. In all cases well-defined crystalline materials, containing hydrogen-bonded networks with quasi-hexagonal sheet lattices were formed. However, the unsubstituted sulphonate (1) formed a 1:1 guanidinium:sulphonate bilayer structure, whilst the unsubstituted phosphonate (2) and arsonate (3) formed 2:1 guanidinium:phosphonate/arsonate single-layer structures with water occluded within the crystal voids. The additional H-bonding interactions resulting in distortion of the crystal voids in (2)/(3) as compared to the symmetrical hexagonal-form in (1). In the case of the nitro-substituted sulphonate derivatives, the 1:1 bilayer structure of the parent (1) was retained for the 3-nitrobenzenesulphonate (4), but transformed to a 1:1 single-layer system for the 4-nitrobenzenesulphonate (6). The reverse was observed for the nitrated phosphonic acids, whereby the 4-nitrobenzenephosphonate anion in (5) caused little disruption to the 2:1 single-layered structure and quasi-hexagonal sheet seen in (2), but the 3-nitrobenzenephosphonate caused a breakdown of the network forming a new, complex ribbon system (7). The greater complexity of the P/As (−2) structures compared to the S (−1) structure is attributed to the higher charge on the former anions providing additional opportunities for H-bonding. The observation of such interactions clearly indicates the likelihood of such species interacting with biologically-important arginine residues in vivo with concomitant unintended, but likely, toxic consequences. [Copyright &y& Elsevier]

Abstract: The crystal structure and spectroscopic characteristics of n-octanohydroxamic acid and the potassium compound of that acid have been investigated by XRD, XPS, FTIR and Raman spectroscopy. XRD revealed that the acid is in the keto Z conformation with the alkyl chains oriented along the z-direction and hydrogen bonding between hydroxamate moieties. Vibrational spectra confirm this conclusion. Chemical analysis, XRD and XPS established that the potassium compound is the acid salt KH(C7H9CONO)2. The crystal structure showed that the hydroxamate groups are also in the keto Z conformation and this is supported by vibrational spectra. In the acid salt, the two hydroxamate moieties are connected by a symmetrical O–H–O short hydrogen bonded linkage between the two hydroxamate oxygen atoms and this explains the absence of a discernible O–H stretch band in the vibrational spectra. Identification of the vibrational bands displayed is supported by deuteration and 15N substitution. [Copyright &y& Elsevier]

Abstract: The complexes of 3-carboxy-4-hydroxybenzenesulfonic acid (5-sulfosalicylic acid, H3SSA) with rubidium(I), caesium(I) and lead(II) have been synthesized and characterized using single-crystal X-ray methods at 130K. The rubidium(I) complex 1, [Rb3(H2SSA)(HSSA)(H2O)4] n , is an unstable hydrate variant of a previously described complex [Rb(H2SSA)(H2O)] n , and comprises three independent and different seven-coordinate metal polyhedra interlinked through oxygen donors of the sulfonate, carboxylate and phenolate groups of the 5-sulfosalicylate ligands (one of which is dianionic, the other monoanionic), and one bridging water, giving a three-dimensional hydrogen-bonded framework polymer structure. The anhydrous caesium(I) complex 2 [Cs(H2SSA)] n , which has been previously described in a room-temperature determination, has a three-dimensional framework polymer structure based on an irregular Cs–O9 repeating unit. Complex 3 with lead(II), [Pb(H2SSA)2(H2O)] n , forms helical step-polymer ribbon substructures having an irregular Pb–O7 coordination centre comprising a single monodentate water and six sulfonate-O donors bridging three separate metals. The carboxylic acid and phenol substituent groups of the 5-sulfosalicylate ligand link the ribbons peripherally through hydrogen bonds, giving a three-dimensional layered framework polymer structure. [Copyright &y& Elsevier]

• We report complexes [Zn(Hal) 2 HL] (Hal = Cl, 1 ; Br, 2) and [Zn(NCS) 2 HL] (3) • Complexes were obtained from 2-formylpyridine nicotinoyl hydrazine (HL) • Crystal packing of 1 and 2 is mainly dictated by the H···Hal/H contacts • Crystal packing of 3 is mainly described by the H···H/N/C/S and C···C contacts In this work we report new discrete mononucler heteroleptic zinc(II) halido complexes of the type [Zn(Hal) 2 HL] (Hal = Cl, 1 ; Br, 2) and zinc(II) pseudohalido complex [Zn(NCS) 2 HL]·1.5MeOH (3 ·1.5MeOH) (HL = 2-formylpyridine nicotinoyl hydrazone). Single crystal X-ray diffraction revealed that in the structures of complexes 1–3 , the Zn(II) metal atom is in a five-coordinated coordination environment and adopts a distorted square pyramidal chromophore, formed by one N 2 O tridentate chelator HL and two halides or thiocyanates, respectively. All complexes display a very similar molecular structure and complexes 1 and 2 are fully isostructural. Crystal packing of 1 and 2 is mainly dictated by the bifurcated N–H···Hal and linear C–H···Hal hydrogen bonds, yielding 1D polymeric chains, which additionally stabilized by intermolecular stacking interactions of the types ZnOCNN···ZnOCNN, ZnOCNN···ZnNCCN and 2-Py···3-Py. These 1D chains are interlinked into a 3D network through C–H···Hal interactions. Crystal packing of 3 ·1.5MeOH is constructed from centrosymmetric dimers formed through linear N–H···O and O–H···N hydrogen bonds, yielding a hydrogen bonded synthon of motif R4 4 (16). These dimers are interlinked trough the C–S···ZnNCCN interactions, yielding 1D polymeric chains, which, in turn, are interlinked through the C–H···O bonds, and ZnNCCN···3-Py and 3-Py···3-Py stacking interactions into a 3D framework. Hirshfeld surface analysis, employed to gain additional insight into interactions responsible for the packing of complexes, and quantitative examination of 2D fingerprint plots revealed that the most important factors in the crystal packing are H···Hal and and H···H contacts in 1 and 2 , and H···H, H···N, H···C and H···S contacts in 3 , further supported by C···C contacts. Density function theory (DFT) calculations were performed to gather more information into structure and bonding since they play an important role in the construction of 3D supramolecular frameworks. A new series of three ZnII coordination compounds were assembled from the 2-formylpyridine nicotinoyl hydrazone ligand and ZnX 2 salts (X = Cl, Br, NCS). Their detailed structural analysis, including non-covalent interactions, is discussed. Image, graphical abstract [ABSTRACT FROM AUTHOR]