“Potassium Potassates” Based on Dihydrotriazinide Ligands: Syntheses, Crystal Structures, and Comparison with Other Alkali Metal Dihydrotriazinide Compounds

Abstract

A series of dihydro‐s‐triazinidopotassium complexes have been synthesised and structurally characterised by X‐ray diffraction. Two of them, the sesqui‐pyridine solvate 2 and the mono‐THF solvate 3, can be classified in formal terms as “potassium potassates” in conforming to the structural pattern established previously for the sesqui‐THF solvate 1, the first reported ate of this type. Formally complex [(R2K)−] anions are linked to K+ cations in polymeric, zig‐zag chain arrangements. Solvate 3 also possesses a unique RK coordination as a direct result of having fewer solvent ligands. DMSO analogue 4 deviates from this uniformity in adopting a centrosymmetric, dimeric (OK)2 ring structure featuring both terminal and bridging DMSO ligands. The dihydro‐s‐triazinidosodium tris(THF) solvate 5 is found to be a monomer. For comparative purposes, the metal‐free, parent triazine molecule 6 has also been subjected to an X‐ray crystallographic study: it displays a 1,2‐dihydro ring setup as opposed to the 1,4‐dihydro alternative existing in the metallo examples. Triazine 6 is also found to form a N–H…Br bridge in the dimeric structure of the lithium bromide bis (THF) solvate 7, a suspected hydrolysis product from the reaction of dihydro‐s‐triazinidolithium 8 and magnesium bromide bis(ether) adduct.

Di-μ-bromo-bis[(tetrahydrofuran)lithium(I)]

“…Molecules of (I) are located on crystallographic centres of inversion with one half-molecule in the asymmetric unit. Geometric parameters are in the normal ranges (Cambridge Structural Database, Version 5.27, November 2005, updated August 2006; MOGUL Version 1.1; Allen, 2002) and agree well with the structure of bis[ 2 -bromo-bis(tetrahydrofuran)lithium] 2-n-butyl-2-tert-butyl-4,6-diphenyl-1H-1,3,5,triazine solvate (Clegg et al, 1997). Furthermore, (I) is isostructural with the chloro compound (Hahn & Rupprecht, 1991).…”

Synthesis and Structural Characterization of Metalated 1,8-Bis(silylamino)naphthalene Derivatives

“…This results in the crystal being composed of helical polymeric chains running parallel to the b axis (Figure 3b). The second lithium-bromine distance of d{Li-BrA} ) 2.717(14) Å is rather longer than the interatomic Li-Br distances normally found in saltlike structures, 74,[79][80][81][82][83][84][85] relatively long Li‚‚‚Br distances have been reported for bridging bromide ligands. [86][87][88] We note that there is one previous report in the literature by Eaborn, Smith, and co-workers of the structural characterization of an Mg-Br‚‚‚Li bridge.…”

Heterobimetallic metallation studies of N,N-dimethylphenylethylamine (DMPEA): benzylic C–H bond cleavage/dimethylamino capture or intact DMPEA complex

“…6 This follows since metallate (ate) complexes (e.g., magnesiates, zincates, aluminates) 7,8 by their very definition must be synergistic species as they contain two (or more) distinct metals that in contacted ion pair structures would both be involved in the transition states of reaction intermediates or in solvent-separated structures facilitate the charge separation by the alkali metal transferring its valence electron to the more electronegative softer metal (e.g., magnesium, zinc or aluminium). In principle, the neutral magnesium, zinc or aluminium components of these compounds, when separated from the alkali metal moieties, cannot reproduce these features (note, however, that homometallic lithium lithiates and potassium potassiates are known [9][10][11][12][13] ) and so are extremely weak bases generally incapable of deprotonating aromatic molecules. A recent example of a synergistic reaction that caught our eye was Strohmann's report 14 of the "sedated metallation" (that is to metallate the desired bond but also to stabilize the resulting carbanion) of the sensitive tertiary amine N,N-dimethylphenylethylamine, DMPEA (also called 2-phenylethyldimethylamine) by the modified Lochmann-Schlosser superbase Bu t Li•Bu t OK (Scheme 1).…”