Crystal structure of 1 with thermal ellipsoids at 50 % probability; hydrogen atoms are omitted for clarity. Selected bond lengths (A) and angles (): B1C1, 1.541(3); B1C2, 1.521(3); B1C3, 1.576(3); C1B1C2, 114.4(7); C2B1C3, 122.4(8); C3B1C1, 123.3(8); C2C4, 1.427(3); C4C5, 1.430(3); C4C5, 1.428(3); C2C6, 1.398(3); C6C7, 1.468(3); C7C8, 1.430(3); C8C1, 1.449(3).
