Complexes of B-Triethylboroxin with Ethylenediamine and Derivatives Thereof

摘要

B-Triethylboroxin forms colorless 1:1 molar complexes of the type (C 2H5BO)3.L with L = ethylenediamine (1) and various derivatives of the latter, i.e., N, N-dimethyl ethylenediamine (2), N,N,N,N'-tetramethyl ethylenediamine (3), piperazine (4), 1,4-diazabicyclo(2.2.2)octane (5), diethylenetriamine (6), and tris(2-aminoethyl)amine (7). The cited boroxin also forms 2:1 molar complexes, 2(C2H5BO)3.L, with L = ethylenediamine (8) and those derivatives of the latter which may be considered as symmetrical species, i.e., N,N,N,';'N'-tetramethyl ethylenediamine (9), piperazine (10), 1,4-diazabicyclo(2.2.2)octane (11), and diethylenetriamine (12). NMR spectroscopic data suggest that the complexes are fluxional in solution at room temperature with a single nitrogen coordinating to the three boron atoms of a given boroxin ring and where, in solution, the 1:1 molar complexes of symmetrical amines appear to exchange their donor sites. There seem to be no principal differences in the complexing of (RBO)3 with R = C2H5 or C6H5. Two species of the unusual composition 3(RBO)3.2H2NCH2CH2NH2 were also identified. Boron compounds, Ethyl radicals, Amines. (mjm)