Temperature Dependence of Molecular Conformation in Solid‐State Phase Transformations of N‐Base Adducts of Bis(1,5‐cyclooctanediyl)diboroxane by X‐ray Diffraction

The structures of the two adducts P‐1 and Q‐1 of bis(1,5‐cyclooctanediyl)diboroxane (1) with pyridine (P) and quinuclidine (Q), which show solid‐„solid”︁ phase transformations at about 127 and 88°C, respectively, have been determined by X‐ray diffraction at −145 and −163°C, respectively. The structure of Q‐1 has also been determined at room temperature and at +50°C. Both P‐1 and Q‐1 are packed in head‐to‐tail pairs and show extensive isothermal as well as temperature‐dependent dynamics in the crystalline phase. The onset of transformations into the new „fluctional solid”︁ phase is discussed in terms of these lattice packings and the observed translational and vibrational dynamics.