The Solid-State Polymerization of 3,5-Dihalo-4-aminobenzoylchlorides: New Structural Perspectives

3-Amino-5-bromo-2-iodo-pyridine

The reaction of 3-amino-5-bromo­pyridine with N-iodo­succinimide in the presence of acetic acid produces the title compound, C₅H₄BrIN, with an iodo substituent in position 2 of the pyridine ring. The crystal structure features rather weak inter­molecular N—H⋯N hydrogen bonds linking the mol­ecules into chains along the z axis of the crystal.

Crystal-to-Crystal Oxidative Deprotonation of a Di(μ-hydroxo) to a Di(μ-oxo) Dimer of Dimolybdenum Units

A crystal-to-crystal transformation of (DAniF)3Mo2(micro-OH)2Mo2(DAniF)3 (1) to (DAniF)3Mo2(micro-O)2Mo2(DAniF)3 (2), where DAniF is the anion (p-anisyl)NC(H)N(p-anisyl), by dioxygen provides rare insight into the deprotonation process effected by dioxygen. In this dimolybdenum system, the conversion occurs without significant loss of crystallinity. Although no intermediates have been directly observed, a compound containing the [(DAniF)3Mo2(micro-OH)(micro-O)Mo2(DAniF)3]+ cation, a proposed intermediate, has been obtained independently. Possible pathways for the overall conversion of 1 to 2 are discussed.

Conformational polymorphism of methacrylamide

The industrially important compound methacrylamide crystallizes as concomitant conformational polymorphs; the monoclinic form contains only the s-cis conformer, while the orthorhombic form contains only the s-trans conformer.