Synthesis and characterization of rare examples of stable potassium and arylcalcium triethylboranate complexes

Stabilization of potassium triethylboranate can be achieved in solution as well as in the solid state with tridentate 1,3,5-trimethyl-1,3,5-triazinane (tmta) as dimeric [(tmta)K(μ-H)BEt3]2 (1). The metathesis reaction of the post-Grignard reagent [2,6-(tol)2C6H3-Ca(thf)3I] (2) with potassium triethylboranate yields an unusual hydrogen bridged organocalcium contact ion pair as hydrocarbon soluble [(thf)(dme)Ca(C6H3-2,6-tol2)HBEt3] (3) which shows no tendency to dismutate to the homoleptic derivatives.

Graphical AbstractBoranates represent widely used reducing reagents. Isolation of potassium and arylcalcium compounds succeeds by employing steric protection with tridentate azabases or bulky aryl groups. The pictogram shows the chain-like structure of {[(tmta)K(μ-H)BEt3]2}∞.Figure optionsDownload as PowerPoint slide