Way back in 1977, the crystal structure of the sulfur ring S 7 was reported.[cite]10.1002/anie.197707151[/cite] The authors noted that “ The δ modification of S 7 contains bonds of widely differing length: this has never been observed before in an unsubstituted molecule. ” No explanation was offered, although they note that similar effects have been observed in S 8 O, S 7 I + and