Bis(l,2-diaryl-l,2-ethylenedithiolato)rnetal(O) complexes (1; metal = Ni. Pd, and Pt) react with quadricyclane (Q) to give selectively 1:l adducts which are identical with the adducts between 1 and norbornadiene (NBD). In the adducts, two sulfur atoms of the different dithiolato ligands are added to one of the double bonds of NBD. The reactions of 1 with Q are 10'-104 times faster than those with NBD. The more electropositive dithiolatometal complexes react faster with Q and NBD. The adducts are dissociated to the free dithiolatornetal complexes and NBD by UV-irradiation (254-436 nm). Upon irradiation with 254 nm light, the photodissociation occurs before the decomposition of the dithiolatometal complexes.Dithiolatometal complexes belong to the set of so-called 'non-innocent complexes', which have peculiar electronic structures. Dithiolatometal complexes interact with several unsaturated hydrocarbons, probably because of their unique electronic configurations.Schrauzer and his coworkers have reported the formation of a dihydro-1 ,&dithiin derivative and a 1 : 1 adduct between bis( 1,2-diphenyl-l,2-ethylenedithiolato)nickel(O) and norbornadiene (NBD).1.2,3 The X-ray diffraction study on a similar adduct (the adduct between bis( 1,2-bis(trifluoromethy1)-1,2-ethylenedithiolato)nickel(0) and NBD) has clarified the structure in which two sulfur atoms of the different dithiolato ligands add to one of the double bonds of NBD.4Baker et al. found that bis( 1,2-bis(trifluoromethyl)-1,2-ethylenedithiolato)nickel(0) reacts with conjugated dienes such as 2,3-dimethyl-l,3-butadiene and 1,3-~yclohexadiene more rapidly than with norbornadiene to give 1 ,Qaddition products. The difference in reactivities between alkene and conjugated diene has been analyzed on the basis of MO correlation."' A similar adduct between bis( 1,2-diphenyl-l,2-ethylenedithiolato)palladium(0) and 1,3cyclohexadiene has also been reported.' M. KAJITANI ET AL. 132Some dithiolatometal complexes such as tris(l,2-bis(trifluoromethy1)-1 ,Zethylenedithiolato)molybdenum(O) catalyze the exothermic isomerization of quadricyclane to norbornadiene.' Some reports have described the photoreactivities of the adducts between the dithiolatometal complexes and norbornadiene. The 1 : 1 adduct between bis( 1 ,Zdiphenyl-l,2ethylenedithiolato)nickel(O) and NBD has been reported to decompose at room temperature, when it is exposed to daylight.' It has also been reported that the 1:l adduct between bis( 1,2-bis(trifluoromethyI)-1,2-ethylenedithiolato)nickel(0) and NBD dissociates to give an equimolar mixture of the dithiolatonickel complex and NBD, when it is irradiated by visible light.5 The measurement of the quantum yields for the photodissociation of the adduct has revealed that the process is quite efficient and solvent-independent.We found that bis( 1,2-diaryl-l,2-ethylenedithiolato)metal(O) complexes react with quadricyclane much more rapidly (=lo4 faster) than with norbornadiene to give selectively 1: 1 adducts without forming dihydro-1 ,Cdithiin derivatives.' In this' p...

Bis(1,2-diphenyl-1,2-ethylenedithiolato)nickel(0) (1a) reacts with quadricyclane (Q) to give a 1:1 adduct which has the same structure as that of the adduct between 1a and norbornadiene (NBD). Q reacts with 1a much faster than NBD. The adduct is thermally stable but photosensitive to dissociate into 1a and NBD.

258ChemInform Abstract The Ni-complex (I) reacts with quadricyclane (II) to form the 1:1 adduct (III) which is also obtained from (I) and norbornadiene (IV), together with the by-product (V). Photolysis of (III) yields (I) and (IV). (IR-, 1H-NMR-, MS-data).

ChemInform Abstract The dithiolatometal complexes (I) are synthesized by the reaction of thiophosphoric acid esters of dithiobenzoins with nickel, palladium, or platinum salts. When refluxing the complexes (I) with quadricyclane (II) in benzene, the adducts (III) are prepared. These are also obtained when the compounds (I) reacts with norbornadiene (IV), although the reaction is much slower and the dihydrodithiins (V) are formed as by-products. The analogous reaction of (Ia) with norbornene (VI) yields the compounds (VII) and (VIII).