Structure of three novel photochromic compounds; X-ray crystallographic and theoretical studies

Dimethoxy-l',3',3'-trimethylspiro(2H- 1,4- benzoxazine-2,2'-indoline), C2oH=N203, Mr = 338.4, monoclinic, P2~/c, a = 12.151 (2), b = 12.090 (4), c = 24.836 (4) A, fl = 90.31 (1) °, V = 3648 (2) A 3, Z= 8, Dx = 1.23 Mg m- 3, a(Cu Ka) = 1.54178 A, /x = 0.637 mm-l, F(000) = 1440, T = 296 K, R = 0.063 for 3106 unique observed reflections. (2) 5,5",7-Tri- methoxy- 1 ',3',3'-trimethylspiro(2H- 1,4-benzoxazine- 2,2'-indoline), C21H24N204, Mr = 368.4, monoclinic, P21/c, a = 8.025 (2), b = 12.415 (3), c = 19.319 (4) A, /3=99.31(2) ° , V =1899.4(8) A 3, Z=4, Ox= 1.288 Mg m -3, A(Cu Ka) = 1.54178 ,~, /x = 0.084 mm -1, F(000) = 784, T= 173 K, R = 0.0486 for 1611 unique observed reflections. (3) 5'-Fluoro- 5,7-dimethoxy- 1 ', 3 ', 3'-trimethylspi ro (2H- 1,4-benz- oxazine-2,2'-indoline), C2oH21N203F, Mr = 356.4, monoclinic, P2~/c, a = 11.484 (3), b = 13.832 (2), c = 11.511 (1)A, /3=98.90(1) ° , V = 1810.4 (6) ,~ 3, Z= 4, Dx = 1.308 Mg m -3, A(Cu ga 0 = 1.54178 ,~, # = 0.754 mm- 1, F(000) = 752, T = 173 K, R = 0.0468 for 2229 unique observed reflections. These three monomeric compounds consist of a substituted ben- zoxazine ring orthogonally coupled to an indoline ring through a spiro C atom.