FUNCTIONALIZED 2-PYRIDYL-SUBSTITUTED METALLO-1,2-ENEDITHIOLATES - SYNTHESIS, CHARACTERIZATION, AND PHOTOPHYSICAL PROPERTIES OF (DPPE)M(S2C2(2-PYRIDINE(IUM))(CH2CH2OR'')) AND -N-2-PYRIDINIUM)](-BIS(DIPHENYLPHOSPHINO)ETHANE)() (R'' = H, ACETYL, LAUROYL M = PD, PT DPPE = 1,2)

The complexes (dppe)M{S2C2(2-pyridine)(CH2CH2OC(O)CH3)} (dppe = 1,2-bi s(diphenylphosphino)ethane; M = Pd, Pt) were prepared from 1-(2-pyridy l)-4-acetoxy-2-bromobutan-1-one and the corresponding (dppe)M(SH)(2) c omplexes. The acetyl group was removed from the metal complexes to yie ld the corresponding alcohols, (dppe)M{S2C2(2-pyridine)(CH2CH2OH)}. Th e lauroyl derivatives (dppe)M{S2C2(2-pyridine)(CH2CH2OC(O)(CH3)} were prepared by esterifying the alcohols with lauroyl chloride. The alkyla ted pyridinium complexes [(dppe)M{S2C2(CH2CH2-N-2-pyridinium)}](+) wer e generated by the addition of either p-toluenesulfonyl chloride or bi s(triazole) o-chloroaryl phosphate to (dppe)M{S2C2(2-pyridine) (CH2CH2 OH)). [(dppe)Pd{S2C2(CH2CH2-N-2-pyridinium)}][BPh4] crystallizes in th e P (1) over bar space group with a = 9.1924(2) Angstrom, b = 16.0191( 2) Angstrom, c = 17.4368(3) Angstrom, alpha 106.292(2)degrees beta = 9 6.235 degrees, and gamma = 95.183(2)degrees. The molecule is best desc ribed as a square planar palladium complex with a planar metallo- 1,2- enedithiolate which is coplanar with the alkylated pyridinium. The pyr idinium-substituted platinum 1,2-enedithiolate complexes have a 1,2-en edithiolate to heterocycle pi charge transfer transition (ILCT) that is the lowest lying band. Like [(dppe)Pt{S2C2(2-pyridinium)(H)}](+), [ (dppe)Pt(S2C2(CH2CH2-N-2-pyridinium)}](+) is luminescent in room-tempe rature solution with two emissive states assigned to the ILCT singlet and triplet. The lifetime of the (ILCT)-I-1 is 0.2 ns, (1)phi = 0.00 2, while the lifetime of the (ILCT)-I-3 is 8.3 mu s, (3)phi = 0.01 (DM SO). While [(dppe)Pt{S2C2(CH2CH2-N-2-pyridinium)}](+) is emissive, the [(dppe)Pt{S2C2(2-pyridinium)(CH2CH2OR '')}](+) complexes are weak emi tters at best in solution with triplet quantum yields of < 0.0001 (DMS O). These photophysical studies suggest that the heterocycle and the 1 ,2-enedithiolate must be coplanar in the ILCT excited states for the c omplexes to be emissive in room-temperature solution.