ALUMINUM-PHOSPHORUS CHEMISTRY - PREPARATION AND STRUCTURAL CHARACTERIZATION OF [ET2ALP(SIME3)2]2, ET(CL)2AL.P(SIME3)3, AND I-BU2(CL)AL.P(SIME3)3

Reactions of R2AlCl (R = Et, i-Bu) and EtAlCl2 With P(SiMe3)3 and LiP( SiMe3)2 were studied to investigate the potential use of dehalosilylat ion and lithium chloride elimination reactions for the preparation of compounds containing either Al-P-Al-P or Al-P-Al-Cl core rings. The di meric compound [Et2AlP(SiMe3)2]2 (1) was isolated from the 1:1 reactio n of Et2AlCl and LiP(SiMe3)2 at -78-degrees-C, as a result of LiCl eli mination. The 1:1 reaction of EtAlCl2 and P(SiMe3)3 Yields Et(Cl)2Al.P (SiMe3)3 (2). Interestingly, a similar reaction between Et2AlCl and P( SiMe3)3 in a 2:1 mole ratio also affords 2, in moderate yield, suggest ing a rearrangement of the original aluminum alkyl halide. However, wh en Et2AlCl was reacted with P(SiMe3)3 in a 1:1 mole ratio, the expecte d adduct Et2(CI)AlP(SiMe3)3 (3) results. Unlike the Et2AlCl reaction, the analogous 2:1 mole reaction of i-Bu2AlCl and P(SiMe3)3 forms the m onochloro adduct, i-BU2AlCl.P(SiMe3)3 (4), rather than a rearrangement product. Compounds 1-4 were characterized by partial elemental analys is, melting point data, as well as H-1, C-13, P-31, and Al-27 NMR spec troscopy. Compounds 1, 2, and 4 were also characterized by single-crys tal X-ray crystallography. Dimer 1 crystallizes in the monoclinic syst em, space group C2/c (C2h6), with unit cell dimensions of a = 18.085(2 ) angstrom, b = 9.452(1) angstrom, c = 20.233(2) angstrom, and beta = 100.30(l)-degrees for Z = 4. Crystals of adduct 2 have unit cell param eters of a = 13.234(2) A, angstrom = 13.147(2) angstrom, and c = 13.04 3(2) angstrom for Z = 4 and belong to the orthorhombic system, space g roup Pca2(1) (C2v5), while adduct 4 crystallizes in the monoclinic sys tem, space group P2(1)/c (C2h5), with cell dimensions of a = 14.986(3) angstrom, b = 11.489(2) angstrom, c = 18.570(4) angstrom, and beta = 119.57 (2)-degrees for Z = 4.