Synthesis and Structural Characterization of the Novel Compounds from the Reactions of Trimethylaluminum or Trimethylgallium with N,O-Donor Crown Ethers

The reactions of two N/O mixed-donor crown ethers, 1,12,15-triaza-3,4:9,10-dibenzo-5,8-dioxacycloheptadecane (OenNdienH₄) and 1,12-diaza-3,4:9,10-dibenzo-5,8-dioxacyclopentadecane (OenNtnH₄) with MMe₃ (M = Al, Ga) are reported. OenNdienH₄ reacted with 3 equiv of AlMe₃ to form (AlMe)(AlMe₂)(OenNdienH₄)(AlMe₃) (1) which contains three different Me_nAl groups:  AlMe, AlMe₂, AlMe₃. OenNtnH₄ reacted with 2 equiv of AlMe₃ to afford (AlMe₂)(OenNtnH₄)(AlMe₃) (2) containing two chemically inequivalent aluminum centers. However, the reaction of OenNdienH₄ with GaMe₃ in 1:3 ratio resulted in (OenNdienH₄)₂(GaMe₂OH)₄ (3). The (Me₂GaOH)₄ component contains an eight-membered Ga−O ring linked via four hydrogen bonds to two molecules of OenNdienH₄ which interacts from opposite sides of the Ga₄O₄ ring. The reaction of OenNtnH₄ with GaMe₃ in 1:2 ratio produced (OenNtnH₄)(GaMe₂OH)₃ (4), a one-dimensional hydrogen bonded system which incorporates one OenNtnH₄ ligand and one nonplanar six-membered ring with alternating Ga and O atoms (GaMe₂OH)₃.