Organogallium chemistry of macrocyclic amines. Synthesis and molecular structure of [Ga(CH3)3]4[(CH3)4[14]aneN4] and [Ga(CH3]2[14]aneN4[Ga(CH3)3

Abstract

Abstract Reaction of trimethylgallium with the tetradentate macrocyclic amine [(CH3)4[14]aneN4] in toluene affords the crystalline adduct product [Ga(CH3)3]4-[(CH3)4[14]aneN4], I. I crystallizes in the orthorhombic space group Pbca (No. 61) with unit cell parameters a = 14.002(2), b = 18.542(3), c = 14.477(3) A, V = 3758.6 A3, and Dcalc = 1.26 g cm−3 for Z = 4. Full-matrix least-squares refinement based upon 2222 observed reflections converged at R = 0.039 (Rw = 0.060). Due to the four trimethylgallium units the macrocycle in I has been forced to assume an exodentate conformation. I resides about a crystallographic center of symmetry with independent GaN bond distances of 2.182(4) and 2.202(4) A. The crystalline product [Ga(CH3)]2[14]aneN4[Ga(CH3)3]2, II, isolated from reaction of trimethyl-gallium with [14]aneN4 in toluene, crystallizes in the triclinic space group P 1 (No. 2) with unit cell parameters a = 8.016(4), b = 9.437(3), c = 9.669(3) A, α = 75.53(3), β = 67.80(4), γ = 73.26(4)°, V = 640.2 A3, and Dcalc = 1.54 g cm−3 for Z = 1. Full-matrix least-squares refinement based upon 1694 observed reflections converged at R = 0.042 (Rw = 0.059). II resides about a crystallographic center of symmetry with a planar Ga2N2 four-membered ring occupying the central cavity of the macrocycle. The Ga2N2 ring has a mean GaN bond distance of 2.009(6) A. The GaNGa bond angle in the Ga2N2 ring is 90.2(2)° while the NGaN bond angle is 89.8(2)°. The ··· Ga contact of 2.847(1) A does not suggest significant metal-metal interaction. The GaN distances in I and II are among the longest reported.