Beryllium Phosphine Complexes: Synthesis, Properties, and Reactivity of (PMe ) BeCl and (Ph PC H PPh )BeCl.

The directed synthesis, spectroscopic properties, and reactivity of bis(trimethylphosphine) beryllium dichloride (1) and bis(diphenylphosphino)propane beryllium dichloride (2) are reported, including the crystal structure of (PMe ) BeCl (1). These four-coordinate beryllium compounds can be alkylated with n-butyllithium ( BuLi) to give three-coordinate (Ph PC H PPh )Be Bu (3) and (PMe )Be Bu (4). PMe can be removed from (PMe )Be Bu (4) in vacuo to yield [ Bu Be] (5). For the first time, the presence of [ Bu Be] as a dimer in solution, which has been postulated for decades, could be observed spectroscopically. This novel, ether-free pathway provides access to beryllium dialkyl compounds that have never been in contact with oxygen-atom-containing reagents or solvents. This "freeness from oxygen" is crucial for semiconductor applications where oxygen is often unwanted and must be avoided at all costs.