8-[(1E)-1-(2-Aminophenyl­iminio)eth­yl]-2-oxo-2H-chromen-7-olate

The title Schiff base, C17H14N2O3, exists as an NH tautomer with the H atom of the phenol group transferred to the imine N atom. The iminium H atom is involved in a strong intra­molecular N+—H⋯O− hydrogen bond to the phenolate O atom, forming an S(6) motif. In the crystal structure, N—H⋯O hydrogen bonds form a C(9) chain parallel to [100] and a C(11) chain parallel to [010], while C—H⋯O hydrogen bonds form a C(11) chain parallel to [010]. The combination of N—H⋯O and C—H⋯O hydrogen bonds generates R 4 3(30) rings parallel to the ab plan

Synthesis and structural characterization of two novel N-heterocyclic carbene complexes of Rh(I)

Two new N-heterocyclic carbene (NHC) ligands with p-methylphenyl and p-methoxyphenyl substituents on 4,5-positions and methoxyethyl pendants on N atoms of the imidazole ring were complexed together with cyclooctadiene and an iodide ion to Rh(I) to give 4a and 4b, respectively. The complexes were characterized by elemental analyses, NMR and IR spectroscopy. In addition, molecular and crystal structure of 4a was determined by single-crystal X-ray methods. In 4a the rhodium ion has distorted square planar coordination geometry chelating with cyclooctadiene (COD) ligand. Molecules of 4a form polymeric chains along the c axis through C-H ⋯ I hydrogen bonds. © 2007 Taylor & Francis

Ligand-to-metal charge transfer resulting in metalloaromaticity of [R,R-Cyclohexyl-1,2-bis(2-Oxidonaphthylideneiminato-N,N',O,O')]Cu(II): A scrutinized structural investigation

Molecular and crystal structure analysis of a tetradentate ligand-to-metal charge transfer (LMCT) complex, [R,R-cyclohexyl-1,2-bis(2-oxidonaphthylideneiminato-N,N',O,O')]Cu(II), are described and characterized by X-ray crystallography and FTIR spectroscopy. The Cu(II) centers are coordinated by four atoms of the donor set [N 2 O 2 ] in a distorted square-planar fashion, which can be attributed to an active electronic delocalization within metallacycles and polychelating property of the pro-ligand. Bond valences of copper centers in four crystallographically independent monomers are slightly distinguished from each other, which is associated with differences in charge delocalization levels of the pro-ligands. Total valence of the copper center is increased with increasing ?-electron donation from naphthalene fragments to metallacycles. This charge transfer leads to ?···? interactions between metallacycles including imine bridges. In addition, decreases in the centroid-centroid distances of ?···? interactions are associated with increased aromatic character of metallacycles. Molecules of the complex are stacked as dimers in the crystal structure formed by ?···? interactions and aggregations of these dimeric formations along a-axis are strengthened by C-H···O type H-bonds and C-H···? interactions. © Springer Science+Business Media, LLC 2010.FEF2007BAP19 Ministerio de Ciencia y Tecnología: MAT2006–01997 Federación Española de Enfermedades RarasAcknowledgments Financial support from the Spanish Ministerio de Educacion y Ciencia (MAT2006–01997 and ‘Factoría de Cris-talización’ Consolider Ingenio 2010), FEDER and C¸ ukurova University Research Foundation (FEF2007BAP19) is gratefully acknowledged