ABSTRACT
Reactions between red phosphorus (Pred) and potassium ethoxide in various organic solvents under reflux convert this rather inert form of the element to soluble polyphosphides. The activation is hypothesized to proceed via a nucleophilic attack by ethoxide on the polymeric structure of Pred, leading to disproportionation of the latter, as judged from observation of P(OEt)3 in the reaction products. A range of solvents has been probed, revealing that different polyphosphide anions (P73-, P162-, P213-, and P5-) can be stabilized depending on the combination of the boiling point and dielectric constant (polarity) of the solvent. The effectiveness of activation also depends on the nature of nucleophile, with the rate of reaction between Pred and KOR increasing in the order t-Bu < n-Hex < Et < Me, which is in agreement with the increasing order of nucleophilic strength. Thiolates and amides were also examined as potential activators, but the reaction with these nucleophiles were substantially slower; nonetheless, all reactions between Pred and NaSR yielded exclusively P162- as a soluble polyphosphide product.
ABSTRACT
Soluble polyphosphide anions were successfully generated in a number of organic solvents by the reaction between shelf-stable red phosphorus and potassium ethoxide. The species were identified by (31)Pâ NMR spectroscopy in solution and by X-ray crystal-structure determination of (Bu4N)2P16 in the solid state. The reaction was scaled up to gram quantities by using a flow-chemistry process.
ABSTRACT
Reactions of alkali metal hydroxides with neat diethyl zinc lead to the formation of oxo-centered clusters M2O(ZnEt2)n (M = Na, n = 3 or M = K, Rb, n = 4). These molecules crystallize in highly symmetric space groups, forming extended structures supported by weak M-H interactions. We discuss the mechanistic implications and relationship of these structures to known (oxo)organozincates.
