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

Abstract

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.

Keywords: Lewis acids; Lewis bases; beryllium; coordination chemistry; phosphines.