A second monoclinic polymorph of di-μ-chlorido-bis­(chlorido{2-[(4-ethyl­phen­yl)imino­meth­yl]pyridine-κ²N,N′}copper(II))

The title compound, [Cu₂Cl₄(C₁₄H₁₄N₂)₂], is a new polymorph of a previously reported compound [Dehghanpour et al. (2011). Acta Cryst. E67, m1296]. The current polymorph was obtained from an acetonitrile solution of the title compound. Like the first polymorph, it is monoclinic (space group P2₁/c). The unique Cu^II ion in the title centrosymmetric dinuclear complex is in a distorted trigonal–bipyramidal coordination environment formed by the bis-­chelating N-heterocyclic ligand, two bridging Cl ligands and one terminal Cl ligand. In the crystal, weak C—H...Cl hydrogen bonds are observed in addition to π–π stacking inter­actions, with a centroid–centroid distance of 3.6597 (18) Å.

[(R)-2,2-Bis(diphenyl­phosphan­yl)-1,1′-binaphthyl-κ²P,P′]{2-[(2R)-1,2-diamino-1-(4-meth­oxy­phen­yl)-3-methyl­but­yl]-5-meth­oxy­phenyl-κC¹}hydrido­ruthenium(II) benzene monosolvate

In the title complex, [Ru(C₁₉H₂₅N₂O₂)H(C₄₄H₃₂P₂)]·C₆H₆, the Ru^II ion is in a distorted octa­hedral coordination environment with the hydride H atom trans to the tertiary carbinamine N atom, giving an H—Ru—N angle of 160.8 (12)°. The equatorial sites are occupied by two P atoms, the secondary carbinamine N atom and a coordinated C atom.

Tetra­methyl 1,4-dimethyl-13,14-dioxa­penta­cyclo­[8.2.1.1^4,7.0^2,9.0^3,8]tetra­deca-5,11-diene-5,6,11,12-tetra­carboxyl­ate

In the title compound, C₂₂H₂₄O₁₄, the relative stereochemistry at the cyclo­butane ring is cis-anti-cis and the methyl groups in the bicyclic rings are syn to each other. The two carboxyl­ate groups attached to the same —C=C— bond are disordered over two sets of sites in a 0.603 (2):0.397 (2) ratio. In the crystal, weak C—H...O hydrogen bonds connect mol­ecules into C(12) chains along [001] incorporating R₂²₂(10) rings.

Tetra-tert-butyl 13,14-dioxapenta­cyclo­[8.2.1.1^4,7.0^2,9.0^3,8]tetra­deca-5,11-diene-5,6,11,12-tetra­carboxyl­ate

The stereochemistry of the title compound, C₃₂H₄₄O₁₀, at the cyclo­butane ring is cis-anti-cis. The mol­ecule lies across an inversion center. In the crystal, weak C—H...O hydrogen bonds connect mol­ecules into chains along [100], forming R₂²(6) rings.

Hexamethyl 13,14-dioxapenta­cyclo­[8.2.1.1^4,7.0^2,9.0^3,8]tetra­deca-5,11-diene-1,4,5,6,11,12-hexa­carboxyl­ate

In the title compound, C₂₄H₂₄O₁₄, the stereochemistry at the cyclo­butane ring is cis-anti-cis and the –COOMe groups in the bicyclic rings are syn to each other. The mol­ecule lies on a twofold rotation axis. In the crystal, weak C—H...O hydrogen bonds connect mol­ecules into chains along [001], forming R₂²(10) rings.

5,6-Dimethyl­pyrazine-2,3-dicarbonitrile

The asymmetric unit of the title compound, C₈H₆N₄, contains two almost planar independent mol­ecules (r.m.s. deviations = 0.026 and 0.030 Å). The crystal studied was a non-merohedral twin with the components in a 0.513 (2):0.487 (2) ratio.