Structure and properties of N-phenylmaleimide derivatives

The crystal structures of 2-chloro-N-phenyl-triphenylphosphoranaminomaleimide 1, N-phenyl-di(triphenylphosphoranamino)maleimide 2a, a nitromethane solvate 2b, N-phenyl-2,3-dithiomaleimide 3, and N-phenyl-2,3-di(thiophenyl)maleimide have been determined. 1 crystallizes in space group P-1 with cell dimensions a = 10.432(6), b = 14.661(5), c = 9.376(4) Å, = 93.13(4), = 92.09(5), and = 79.08(4)°, 2a crystallizes in space group P2₁/c with cell dimensions a = 11.272(2), b = 28.910(7), c = 12.702(2) Å, and = 115.31(2)°, 2b crystallizes in space group P-1 with cell dimensions a = 13.140(2), b = 13.796(3), c = 11.755(3) Å, = 99.62(2), = 100.23(2), and = 102.74(2)°, 3 crystallizes in space group C2/c with cell dimensions a = 42.926(5), b = 5.757(6), c = 8.259(3) Å, and = 99.71(3)°, and 4 crystallizes in space group C2/c with cell dimensions a = 20.055(4), b = 10.370(6), c = 18.690(7) Å, and = 100.32(2)°. Vicinal diazides of five-membered rings undergo the normal Staudinger reaction to form triphenylphosphoranamino derivatives. Compounds 1 and 2 fluoresce strongly, but nitromethane quenches the fluorescence of 2.