tetraspiro[dibenzo[d,f][1,3,2]dioxaphosphepine-6,2'-[1,3,5,7,2,4,6,8]tetrazatetraphosphocine-4',6''-dibenzo[d,f][1,3,2]dioxaphosphepine-6',6'''-dibenzo[d,f][1,3,2]dioxaphosphepine-8',6''''-dibenzo[d,f][1,3,2]dioxaphosphepine] (non-preferred name) [33486-9