title: Structures and Rotational Barriers of a Diiodobinorsnoutane: Energetic Preference for Gauche Conformation.
abstract: The diiodobinorsnoutane, bi(5-iodopentacyclo[4.3.0.0(2,4).0(3,8).0(5,7)]non-4-yl) (5), exists in a sterically hindered gauche conformation rather than an anti or an averaged (freely rotating) C2v structure. Density functional theory (DFT) predictions place the gauche conformation 11 kcal/mol more stable than the anti conformation with a barrier of 17 kcal/mol connecting the minima. These are consistent with variable-temperature NMR (17.1 ± 0.8 kcal/mol) estimates and X-ray analysis. Predictions of the torsional profiles of the yet-unsynthesized bromo-, chloro-, and fluoro- analogues show a progressive lowering of the barriers.
authors.affiliation: Department of Chemistry, Saint Joseph's University , 5600 City Avenue, Philadelphia, Pennsylvania 19131, United States.
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Herres
authors.affiliation: Department of Chemistry, Saint Joseph's University , 5600 City Avenue, Philadelphia, Pennsylvania 19131, United States.
authors.forename: Caitlin A
authors.initials: CA
authors.lastname: Moran
authors.affiliation: Department of Chemistry, Saint Joseph's University , 5600 City Avenue, Philadelphia, Pennsylvania 19131, United States.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Forman
authors.affiliation: AstraZeneca Pharmaceuticals, 1800 Concord Pike, Wilmington, Delaware 19850, United States.
authors.forename: James E
authors.initials: JE
authors.lastname: Hall
authors.affiliation: AstraZeneca Pharmaceuticals, 1800 Concord Pike, Wilmington, Delaware 19850, United States.
authors.forename: John P
authors.initials: JP
authors.lastname: McCauley
authors.affiliation: AstraZeneca Pharmaceuticals, 1800 Concord Pike, Wilmington, Delaware 19850, United States.
authors.forename: Don E
authors.initials: DE
authors.lastname: Pivonka
authors.affiliation: AstraZeneca Pharmaceuticals, 1800 Concord Pike, Wilmington, Delaware 19850, United States.
authors.forename: Steven S
authors.initials: SS
authors.lastname: Wesolowski