1H-inden-1-one, 2-(2,3-dihydro-1H-inden-1-ylidene)-2,3-dihydro- 2,3-dihydro-1,2'-biinden-1'(3'H)-one InChI=1/C18H14O/c19-18-15-8-4-2-6-13(15)11-17(18)16-10-9-12-5-1-3-7-14(12)16/h1-8H,9-11H2/b17-16