First structurally characterised lithium hexafluorophosphate complexes with acyclic Lewis bases: ion-separated [Li2(hmpa)5]2+·2(PF6–) and ion-contacted [(pmdeta)LiPF6]2 [hmpa = (Me2N)3PO; pmdeta = MeN(CH2CH2NMe2)2]
Abstract
Reactions of NH4PF6 with BunLi in toluene containing hmpa or pmdeta afford the complexes [Li2- (hmpa)5]2+·2(PF6)– 1, an ion-separated species containing an unusual dinuclear dication, and [(pmdeta)LiPF6]2 2 in which PF6– anions bridge (pmdeta)Li+ units via Li···F interactions, this being the first observation of a bridging mode for this anion; ab initio MO calculations help explain the very different structures of 1 and 2.