Beryllium Phosphine Complexes: Synthesis, Properties, and Reactivity of (PMe₃ )₂ BeCl₂ and (Ph₂ PC₃ H₆ PPh₂ )BeCl₂

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 (PMe₃ )₂ BeCl₂ (1). These four-coordinate beryllium compounds can be alkylated with n-butyllithium (ⁿ BuLi) to give three-coordinate (Ph₂ PC₃ H₆ PPh₂ )Beⁿ Bu₂ (3) and (PMe₃ )Beⁿ Bu₂ (4). PMe₃ can be removed from (PMe₃ )Beⁿ Bu₂ (4) in vacuo to yield [ⁿ Bu₂ Be]₂ (5). For the first time, the presence of [ⁿ Bu₂ Be]₂ 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.