2H -[1,3]Oxazino[3,2-α]indolin-4(3H )-ones: A Class Of Polyheterocyclic Indole-Based Compounds

Hierarchical, Lithium‐Templated Assembly of Helicate‐Type Complexes: How Versatile Is This Reaction?

Catechol ligands that bear carbonyl functions such as esters or aldehydes in the 3-position (1a–c-H2) form triple-stranded, helicate-type complexes [Li3(1a–c)6Ti2]– with titanium(IV) and the corresponding double-stranded compounds [Li2(1a–c)4B2] with boron(III) in hierarchical, lithium-templatedprocesses. The related 8-hydroxyquinoline ligands 2a,b-H can be used for the formation of similar complexes[Li3(2a,b)6M2]+ with cobalt(II), nickel(II), or zinc(II). A prerequisite for the formation of the lithium-bridged dimers is a negative charge of the mononuclear complexes, which are able to electrostatically attract the lithium cations and thus compensate the repulsion between the cations. (© Wi…

Structural Versatility of Anion−π Interactions in Halide Salts with Pentafluorophenyl Substituted Cations

A series of pentafluorophenyl substituted ammonium, iminium, amidinium, and phosphonium halides are presented which show extensive anion-pi interactions. Hereby, the well-known anion-donor-pi-acceptor as well as "eta6" anion-pi-complex type interactions are observed. The latter is supported by fixation of the anion on top of the aromatic system through hydrogen bonding. This arrangement was investigated by theoretical methods showing a highly attractive anion-pi interaction. In addition an eta2-type coordination of the anions to only two C-atoms of the electron-deficient ring system is described.

Expanding the Size of Catecholesters - Modified Ligands for the Hierarchical Assembly of Dinuclear Titanium(IV) Helicates

Five 2,3-dihydroxybenzoic acid derivatives 1 – 5 were used as starting materials to obtain the corresponding methyl and ethyl esters. Those were applied as ligands in the hierarchical self-assembly of lithium-bridged dinuclear titanium(IV) complexes 1a–4a, 1b–3b, and 5b. The equilibria between the mononuclear triscatecholate complexes (monomer) and the dinuclear helicates (dimer) were observed by 1H NMR spectroscopy in [D6]DMSO and [D4]MeOH at room temperature.

CCDC 1407855: Experimental Crystal Structure Determination

Related Article: David Van Craen, Marita de Groot, Markus Albrecht, Fanfang Pan and Kari Rissanen|2015|Z.Anorg.Allg.Chem.|641|2222|doi:10.1002/zaac.201500543

CCDC 1575105: Experimental Crystal Structure Determination

Related Article: Jan M. Hartmann, Marita de Groot, Katja Schäringer, Kira Henke, Kari Rissanen and Markus Albrecht|2018|Eur.J.Org.Chem.|2018|901|doi:10.1002/ejoc.201701630