Structural Chemistry of Organomercury Compounds. Role of Secondary Interactions

The structures of the organomercury compounds have been reviewed from the point of view of the secondary bonds which mercury atom forms with the surrounding atoms. These bonds, though rather labile, exhibit a definite influence on the crystal structure which is manifested in a peculiar coordination around the mercury atom. This influence has to be studied systematically since the mercury coordination polyhedra in the crystal structure of organomercury compounds are far from being regular. The review has been restricted to the structures in which the secondary bonds of mercury are shorter than the sum of the van der Waals radii. The upper limit of the distances within the coordination polyhedron cannot be well substantiated while the distances larger than the sum of the van der Waals radii may be also influencial in the structure. The influence of the long-range contacts, both on the molecular structure as a whole as well as on the stability of the secondary bonds, may be quite essential. The long-range contacts actually reproduce the solvation effect in chemical reactions in solutions. From this point of view the X-ray diffraction data are useful for the study of the chemical reaction mechanism in the organic chemistry of mercury

Structural Chemistry of Organomercury Compounds. Role of Secondary Interactions

The structures of the organomercury compounds have been reviewed from the point of view of the secondary bonds which mercury atom forms with the surrounding atoms. These bonds, though rather labile, exhibit a definite influence on the crystal structure which is manifested in a peculiar coordination around the mercury atom. This influence has to be studied systematically since the mercury coordination polyhedra in the crystal structure of organomercury compounds are far from being regular. The review has been restricted to the structures in which the secondary bonds of mercury are shorter than the sum of the van der Waals radii. The upper limit of the distances within the coordination polyhedron cannot be well substantiated while the distances larger than the sum of the van der Waals radii may be also influencial in the structure. The influence of the long-range contacts, both on the molecular structure as a whole as well as on the stability of the secondary bonds, may be quite essential. The long-range contacts actually reproduce the solvation effect in chemical reactions in solutions. From this point of view the X-ray diffraction data are useful for the study of the chemical reaction mechanism in the organic chemistry of mercury

Remote Asymmetric Induction in Free-Radical Cycloaddition Leading to Trans-Cyclohexano-Fused 12-Membered Crown Thioethers

Homolytic cycloaddition of dithiol 1, derived from trans-1,2-cyclohexanediol, to alkynes induced by Pr3BO2 occurs with 1,6-asymmetric induction to afford predominantly (1S∗, 6R∗, 12S∗)-trans-cyclohexano-fused 12-membered crown thialactones 4a-c. No pronounced diasteroselectivity was found in the corresponding reactions of dithiol 2, derived from cis-1,2-cyclohexanediol

Structural study of compounds modelling elementary polymer units, 4.† Molecular and crystal structures of three isomers of 4,4′-bis(x-hydroxyphenoxy)octafluorobiphenyl

The paper presents an X‐ray study of the isomers 4,4′‐bis(2‐hydroxyphenoxy)‐, 4,4′‐bis(3‐hydroxyphenoxy)‐, and 4,4′‐bis(4‐hydroxyphenoxy)octafluorobiphenyl, which are used as monomers in the synthesis of polyarylates. The molecular packing in crystals is characterized by intermolecular H‐bonds, donor‐acceptor and stacking interactions between the benzene rings of adjacent molecules, which results in considerable distortion of the molecular geometry. Notably, bending of biphenyl fragments accompanied by distortion of benzene ring planarity was observed, along with unusual conformations of oxydiphenylene fragments and distortions of bond angles at ipso‐carbon atoms bonded to ether oxygen atoms

Stereoselective Free Radical Cycloaddition-macrocyclization in Facile Synthesis of \u3cem\u3etrans\u3c/em\u3e-cyclohexano-fused 12-membered Crown Thioethers

Homolytic cycloaddition of dithiols 1,2 derived from trans- and eis-1,2-cyclohexanediols to alkynes, induced by Pr3B-O2, offers an extremely simple approach to trans- and cis-cyclohexano-fused 12-membered crown thialactones 4a-c-7a-c. The reaction of trans-1 proceeds with pronounced remote 1,6-asymmetric induction to give predominantly (IS *, 6R *, 12S *)-4a–c, while cis-2 reacts nonstereoselectively. Basing on molecular mechanics calculations the stereoselectivity is rationalized as a result of entropy favored pathway of macrocyclization

Stereoselective Free-Radical Cycloaddition-Macrocyclization in Facile Synthesis of Trans-Cyclohexano-Fused 12-Membered Crown Thioethers

Homolytic cycloaddition of dithiols 1,2 derived from trans- and eis-1,2-cyclohexanediols to alkynes, induced by Pr3B-O2, offers an extremely simple approach to trans- and cis-cyclohexano-fused 12-membered crown thialactones 4a-c-7a-c. The reaction of trans-1 proceeds with pronounced remote 1,6-asymmetric induction to give predominantly (IS *, 6R *, 12S *)-4a–c, while cis-2 reacts nonstereoselectively. Basing on molecular mechanics calculations the stereoselectivity is rationalized as a result of entropy favored pathway of macrocyclization

Solvent effects on C=O stretching frequencies of some 1-substituted 2-pyrrolidinones

In an effort to model solute–solvent interactions, the C=O stretching frequencies of five 1-substituted 2-pyrrolidinones and four other carbonyl-containing compounds were measured for 30 common solvents. These were then correlated with four empirical parameter sets and one theoretical (computational) parameter set. While an empirical parameter set gave the best correlation equations, the theoretical parameter equations are physically and statistically significant. Solvent volume, polarizability and hydrogen bond donor acidity (capacity) terms are significant in the correlation equations.