Dynamic chiral-at-metal stability of tetrakis(d/l-hfc)Ln(iii) complexes capped with an alkali metal cation in solution

摘要: Chiral tetrakis(β-diketonate) Ln(III) complexes Δ-[NaLa(d-hfc)4(CH3CN)] (1) and Λ-[NaLa(l-hfc)4 (CH3CN)] (2) (d/l-hfc− = 3-heptafluo-robutylryl-(+)/(−)-camphorate) are a pair of enantiomers crystallize in the same Sohncke space group (P212121) with dodecahedral (DD) geometry. Typically positive negative exciton splitting patterns around 320 nm were observed solid-state circular dichroism (CD) spectra 1 2, which indicate that their shell configurational chiralities Δ Λ, respectively. The apparent bisignate couplets CD [CsLn(d-hfc)4(H2O)] [Ln La (3), Yb (5)] [CsLn(l-hfc)4(H2O)] (4), (6)] show they absolute configurations denoted crystallographic data 5 reveals its coordination polyhedron is square antiprism (SAP) geometry it undergoes phase transition from triclinic (α phase, P1) to monoclinic (β C2) upon cooling. difference between two phases brought about by temperature dependent behaviour water molecules, but this did not affect chirality Δ-SAP-[Yb(d-hfc)4]− moiety. Furthermore, time-dependent CD, UV-vis 19F NMR applied study solution behavior these complexes. It was found chiral-at-metal stability three pairs different affected both Ln3+ M+ ion size. results Cs+ cation can retain metal center stablize structures [Ln(d/l-hfc)4]− or dissociated tris(d/l-hfc)Ln(III) species for longer time than Na+ cation, important successfully lock Yb3+ complex solution. This reasoned short Cs+⋯FC, Cs+⋯O–Yb Cs+⋯Yb3+ interactions crystal structure α-5 further confirmed chiral self-assembly 6 [Yb(H2O)(d/l-hfc)3] induced CsI CHCl3