The crystal and molecular structure of [K·DB-18-C-6][AlMe₃NO₃]·0.5C₆H₆

Abstract

The use of dibenzo-18-crown-6 in the synthesis of trimethylaluminum adducts of KNO₃ results in the formation of a 1/1 adduct, [K·DB-18-C-6]-[AIMe₃NO₃]. The crystal structure of [K·DB-18-C-6][AlMe₃NO₃]-has been determined from single-crystal X-ray diffraction data collected by counter methods. The title compound crystallizes in the monoclinic space groupP2₁/c (No. 14) with unit cell parametersa=11.804(3),b=28.828(4),c=9.118(3) Å, β=96.61(3)°, andD _calc=1.23 forZ=4. Least-squares refinement gave a final conventionalR value of 0.045 for 983 independent observed reflactions. The potassium atom is centered among the six oxygen atoms of the crown at an average K⋯O contact of 2.74(2) Å. Its environment is completed by an oxygen atom of a nitrate anion (2.88 Å) and a benzo group (>3.44 Å) of a neighboring crown ether. The trimethylaluminum moeity is coordinated to the nitrate anion by an oxygen atom at an Al-O bond distance of 1.92(1) Å.