Synthesis and X-ray crystal structure of novel tetramethylphosphonium dichlorodimethylaluminate

The reaction of tris(trimethylsilyl)phosphine with dimethylaluminum chloride in 1,2-dimethoxyethane (monoglyme) displays an important role as building blocks that results in the production of novel tetramethyl phosphonium dichlorodimethylaluminate and the already known dimer compound (bis(2,2-methoxy-ethanolato-O,O′)-tetramethyl-di-aluminum). The newly formed tetramethyl phosphonium dichlorodimethylaluminate [(CH₃)₄P]⁺[(CH₃)₂AlCl₂]⁻ crystallizes in the monoclinic space group P2₁/c, having unit cell with lattice constants a = 7.522, b = 11.644, c = 14.841 Å, and β = 99.32° includes four formula units. The mean values of the bond lengths are P-C 1.787 Å, Al-Cl 2.224 Å, and Al-C 1.966 Å. Both phosphorus and aluminum are tetrahedrally surrounded in organophosphonium-based cations and organoaluminium-based anions. The geometry of the dichlorodimethylaluminate anion shows a distorted tetrahedron.