... Space group, a (Å), 8.507 (3). b (Å), 10.613 (4). c (Å), 12.457 (3). 80.05 (3). ... 0.010. (e Å -3 ), 4.30. (e Å -3 ), -2.50. Extinction method, Larson (1970 [Larson, AC (1970). Crystallographic Computing, edited by F. R. Ahmed, SR Hall & CP Huber, pp. 291-294. ... Acta Cryst. B37, 1433-1435 ...