OLIGOMER ANALOGS OF POLY(AZATHIENE) (SN)(X)

According to X-ray diffraction analysis and PM3 calculations, the Ph-N =S=N-S-Ph molecule in the E, Z-configuration, like the NSNS monomer un it of poly(azathiene) (SN)(x) in the same configuration, is essentiall y nonplanar in crystals and in vacuum. The more extended derivative (M e(3)SiN=S=N-)(2)S in crystals has a planar E, Z, Z, E-configuration wi th pseudo C-2v, symmetry, whereas in vacuum the most stable conformati on is the nonplanar conformation of the same isomer with C-2 symmetry In going from (Me(3)SiN=)(2)S to (Me(3)SiN=S=N-)(2)S, lengthening of t he azathiene chain by the NSNS unit is accompanied by a change in the configuration motif (E, Z; E, Z, Z, E), as opposed to the case studied earlier in which the motif was preserved (E, Z; E, Z, EZ).