Structures of Organo Alkali Metal Complexes and Related Compounds

Abstract

The investigation of the reactivity and structure of organometallic compounds of alkali metals has experienced a blustering development in the last decades. This class includes compounds that are especially important for our understanding of chemical bonding and also quite simple, for example methyl alkali metal complexes, whose structures have been unequivocally determined. Organometallic compounds of alkali metals (and also magnesium) generally exist as ion aggregates whose properties can be significantly modified through solvation by, for example. ether or amines. Important advances in the synthesis of new compounds, especially those of the heavier alkali metals, have been based on these results. It was long believed that the alkali metals had little tendency to undergo coordination and that their coordination chemistry would offer few surprises. This picture has now changed completely. Results from crystal structure investigations have revealed a variety of often surprising structure types (rings, heterocubanes, chains, layers, etc.) not only with the organometallic compounds but also with the amides, imides, alkoxides, phenoxides, enolates, and even halides. A comparison reveals interesting similarities between compounds that appear to be so different and leads to a general classification of the structure types possible with C, N, 0, and halo ligands.

Characterization of Dimeric and Tetrameric μ‐Hydroxide Ytterbium(III) Binaphtholate Complexes

“…The potassium K1, which is bound by only one THF, exhibits K À C p-interactions with a neighboring naphthyl ring ( Figure 5). [23] The three K À C-p distances in this complex are 3.36, 3.35, and 3.53 . The THF ligand is directed away from the naphthyl ring to maximize K À C p-interactions and to relieve unfavorable steric congestion.…”

Coordination chemistry of a mixed donor bidentate ligand with nickel. A tetrameric enolate of sodium that binds a phosphine donor

“…Other than the layered aggregates of simple alkoxide salts, the structural motifs encountered in the solid-state structural analyses of sodium alkoxides and enolates, {NaOR},,, range from tetramer (n = 4) to hexamer units (n = 6) with even nonameric structures (n = 9) having been found (22). In these structures, each sodium cation is generally found to be threecoordinate and sitting at the corner of the appropriate geometrical shape.…”

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

“…However, thus far we have not managed the challenging feat of going one better by capturing a metallated derivative of DMPEA itself. That notwithstanding, as now discussed this study has been successful in unearthing a novel bimetallic complex containing intact DMPEA, that is, Completing the NMR analysis, the 7 Li NMR spectrum showed a single sharp resonance at 1.89 ppm indicating only one lithium environment. These data pointed to the amine molecule interacting with the bimetallic reagent in some way, but without deprotonation having occurred, as its PhCH 2 atoms were still present.…”

“…[73] However, while carrying out this present work, a parallel study [74] cross-examining previous data on " [ bases, not alkyl bases. An interesting point to note is that (Me 2 NLi) n on its own is probably polymeric given lithium's propensity for high aggregation when connected to such a small anion [78][79] (though its crystal structure still remains elusive), but in this reaction it is never given the opportunity to aggregate which suggests the trans-metal-trapping step by the aluminium base residue occurs rapidly. …”