title: Selection of a pentameric host in the host-guest complexes [[[[P(mu-NtBu)]2(mu-NH)]5].I]-[Li(thf)4]+ and [[[P(mu-NtBu)]2(mu-NH)]5].HBr.THF.
abstract: The structures of the host-guest complexes [[[[P(mu-NtBu)]2(mu-NH)]5]I]-.[Li(thf)4]+ [2.I[Li(thf)4]] and [[[P(mu-NtBu)]2(mu-NH)]5].HBr.THF (2.HBr.THF) show that increased distortion of the framework of the pentameric macrocycle [[[P(mu-NtBu)]2(mu-NH)]5] (2) occurs with the larger halide ions. Theoretical studies show that the thermodynamic stabilities of the model host-guest anions [2.X]- (X=Cl, Br, I) are in the order Cl- approximately Br->I-, that is, the reverse of the templating trend observed experimentally. These studies support the view that the selection of the pentamer 2 over the tetramer [[[P(mu-NtBu)]2(mu-NH)]4] (1) is kinetically controlled, a conclusion which is also consistent with the previous observation that the frameworks of 1 and 2 are not in dynamic equilibrium with each other.
authors.affiliation: Chemistry Department, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
authors.forename: Felipe
authors.initials: F
authors.lastname: García
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Goodman
authors.forename: Richard A
authors.initials: RA
authors.lastname: Kowenicki
authors.forename: Istemi
authors.initials: I
authors.lastname: Kuzu
authors.forename: Mary
authors.initials: M
authors.lastname: McPartlin
authors.forename: María A
authors.initials: MA
authors.lastname: Silva
authors.forename: Lucía
authors.initials: L
authors.lastname: Riera
authors.forename: Anthony D
authors.initials: AD
authors.lastname: Woods
authors.forename: Dominic S
authors.initials: DS
authors.lastname: Wright