Juan Carlos Munoz

Selectivity in C–Cl bond activation of dichloroarenes by photogenerated Cp*Re(CO)2: combined experimental and DFT studies

The photochemical reaction of the d6 Re(I) complex Cp*Re(CO)3 with several substituted dichloroarenes (1-R-2,4-dichlorobenzene; R = Me, OMe, CF3 and F) yields the insertion products trans-Cp*Re(CO)2(C6H3ClR)Cl. The C–Cl bond activation of 2,4-dichloroanisole and 2,4-dichloro-1-fluorobenzene occurs at position 2 (ortho to the methoxy and fluoro substituents, respectively), whereas for 2,4-dichlorotoluene and 2,4-dichloro-1-trifluoromethylbenzene the C–Cl bond in position 4 (para to the Me and CF3 groups, respectively) is cleaved. The products have been characterized by elemental analyses and spectroscopic techniques, and by X-ray crystallography for the complexes trans-Cp*Re(CO)2(5-chloro-2-methoxyphenyl)Cl and trans-Cp*Re(CO)2(3-chloro-4-methylphenyl)Cl. DFT(B3PW91) calculations have been carried out to explain the selectivity observed in the isolated insertion products. It is shown that the Re–aryl bond dissociation energy is stronger in the observed isomer. This is analyzed as originating from a combination of electronic and steric factors.

Two hydrates of 2,6-bis­(1H-benzimidazol-2-yl)­pyridine

The structures of the mono- and sesquihydrates of 2,6-bis(1H-benzimidazol-2-yl)pyridine (bbip) are reported. Phase (I), C(19)H(13)N(5).H(2)O, has one water and one bbip molecule in the asymmetric unit, while phase (II), C(19)H(13)N(5).1.5H(2)O, has three water molecules and two bbip molecules in the asymmetric unit. The compounds exhibit very similar molecular geometries but different packing organizations, which result from intricate hydrogen-bonding schemes.

Bis­[2,6-bis(1H-benzimidazol-2-yl-κN3)pyridinato-κN]zinc(II)

The structure of [Zn(C(19)H(12)N(5))(2)], which is monomeric and consists of neutral Zn(bbip-H)(2) entities [bbip-H is the anionic form of bis(benzimidazolyl)pyridine, formed by the loss of one H atom], has been solved from a racemic twin. The Zn atom lies at a site with imposed 222 symmetry and the bbip-H ligand has imposed twofold symmetry. The imidazolyl H atom is disordered over two symmetry-related positions, thus raising the molecular symmetry as required by the space group. The angle between the planes of the two coordinated bbip-H ligands is 84.6 (3) degrees, so defining a distorted octahedral environment around the metal atom.

(2Z)-3-(5-Hydroxy-4-oxo-4H-chromen-3-yl)acrylonitrile

The title compound, C12H7NO3, consists of a chromone moiety substituted in position 3 with an acrylonitrile group in a Z configuration. The two planar groups are twisted with respect to one another. The only significant hydrogen bond in the structure is an intramolecular O-H...O bond. pi-pi contacts connecting aromatic groups and C-H...O intermolecular weak interactions lead to a supramolecular layer arrangement.