Diethylthiotetrathiafulvalenoselenoquinone-1,3-dithiole-methide (1a) and -1,3-benzodithiolemethide (2a) were newly prepared as a donor molecule, which was colored blue in contrast to the corresponding thiocarbonyl- (Ib and 2b) (green) and carbonyl-analogues (Ic and 2c) (red). From comparison of their first redox potentials, la (2a) possesses almost the same electron-donating ability to Ib (2b) and Ic (2c). The reaction of 2a with P(n-Bu)(3) afforded a coupled ylidene compound (3) albeit in low yield, which can be expected as another new donor molecule.