Synthesis and structural variations of substituted phenylamide complexes of the heavy alkaline earth metals calcium, strontium and barium

Abstract

Starting material KN(H)C₆H₃-2,6-F₂ was prepared via a transamination reaction from KNH₂ and 2,6-F₂C₆H₃NH₂ in THF and crystallized from 1,4-dioxane (diox) as the three-dimensional polymer [(diox)_1.5K{N(H)-2,6-F₂C₆H₃}·diox_0.5]_∞ (1). The metathesis reaction of (THF)₄CaI₂ with KN(Me)Ph in THF yields monomeric (THF)₄Ca[N(Me)Ph]₂ (2) with a nearly linear N–Ca–N moiety of 179.84(8)°. The metathesis reaction of (THF)₄CaI₂ with KN(H)Mes yields trinuclear (THF)₆Ca₃[N(H)Mes]₆ (3) with a linear Ca₃ fragment and bridging 2,4,6-trimethylphenylamido groups. The reaction of 1 with (THF)₄CaI₂ gives dinuclear (THF)₅Ca₂[N(H)-2,6-F₂C₆H₃]₄·2THF (4) with three bridging and one terminally bound 2,6-difluorophenylamide. A similar reaction of (THF)₅SrI₂ with KN(H)-2,6-F₂C₆H₃ yields dinuclear (THF)₆Sr₂[N(H)-2,6-F₂C₆H₃]₃I·THF (5) in which the iodide anion binds terminally. This iodide ligand cannot be substituted as easily by excess KN(H)-2,6-F₂C₆H₃. The metathesis reaction of (THF)₅BaI₂ with KN(H)-2,6-F₂C₆H₃ leads to the formation of [(THF)₂Ba{N(H)-2,6-F₂C₆H₃}₂]_∞ (6) which crystallizes as a one-dimensional polymer with bridging 2,6-difluorophenylamide anions and additional Ba–F-bonds.