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Reaction of Me3Ga and Me3Al with the tertiary-tetraaza analog of adamantane, hexamethylenetetramine (N4-Ada). Syntheses and molecular structures of [(Me3M)n · N4-Ada] (n = 1–4, M  Ga or Al)

1993; Elsevier BV; Volume: 445; Issue: 1-2 Linguagem: Inglês

10.1016/0022-328x(93)80180-j

1872-8561

Jameica B. Hill, Sheila J. Eng, William T. Pennington, Gregory H. Robinson,

Inorganic Chemistry and Materials

Reaction of Me3Al or Me3Ga with hexamethylenetetramine, N4-Ada (Ada = adamantane), in toluene affords the crystalline addition products [(Me3M)n · N4-Ada] (n = 4, M  Ga (I); n = 3, M  Ga (II); n = 3, M  Al (III); n = 2, M  Ga (IV); n = 2, M  Al (V); n = 1, M  Ga (VI). Compound I crystallizes in the triclinic space group P1 (no. 2) with unit cell parameters a = 10.365(3), b = 11.814(6), c = 11.991(6), Å, α = 94.16(4), β = 92.56(3), γ = 92.44(3)°, V = 1461(1), Å3, and Dcalc. = 1.36 g cm−3 for Z = 2. Least-squares refinement based on 2600 observed reflections converged at R = 0.075, Rw = 0.089. Compound III crystallizes in the monoclinic space group P21/c (no. 14) with unit cell parameters a = 7.416(2), b = 16.687(6), c = 19.143(6) Å, β = 91.71(2)° V = 2368(1) Å3, and Dcalc. = 1.00 g cm−3 for Z = 4. Least-squares refinement based on 2235 observed reflections converged at R = 0.085, Rw = 0.102. The mean GaN bond distance in I is 2.29 (3) Å, while the corresponding AlN distance is 2.11 (1) Å. The GaN distance of 2.318 (9) Å in I is the longest such distance reported. A molecular mechanics study was used to show that the sequential addition of Me3M (M  Al or Ga) units to N4-Ada significantly affects the relative Lewis basicities of the nitrogen atoms of the amine.