Crystal structures of 2,4-dimethylthioxanthene 10,10-dioxide, 2,4,9-trimethylthioxanthene 10,10-dioxide,and 2,4-dimethyl-9-isopropylthioxanthene 10,10-dioxide

The structures of 2,4-dimethylthioxanthene 10,10-dioxide, 1 , 2,4,9-trimethylthioxanthene 10,10-dioxide, 2 , and 2,4-dimethyl-9-isopropylthioxanthene 10,10-dioxide, 3 , have been determined by x-ray diffraction. The central ring of the thioxanthene ring system is in a boat conformation. The 9-methyl substituent in 2 and the 9-isopropyl substituent in 3 are both in the boat-axial conformation with respect to the central ring. The folding angles between the planes of the two benzo rings are 136.6°, 142.9°, and 134.3° for 1, 2 , and 3 , respectively.