REACTIONS OF RUTHENIUM ACETYLIDE COMPLEXES WITH ISOTHIOCYANATE

Treatment of Cp(PPh3)[P(OMe)(3)]RuC=CPh (2; Cp = eta(5)-C5H5) with PhN =C=S at room temperature affords the [2 + 2] cycloaddition product Cp( PPh3)[P(OMe)(3)]RuC=C(Ph)C-(=NPh)S (3a), containing a four-membered ri ng, and the neutral vinylidene phosphonate complex Cp(PPh3)[P(=O)(OMe) (2)]Ru=C=C(Ph)C(SH)=NPh (4a) in a 9:1 ratio. Formation of 4a results f rom an Arbuzov-like dealkylation reaction possibly after addition of P hN=C=S. The same reaction at 40 degrees C affords a higher yield of 4a and Cp(PPh3)[P(OMe)(3)]RuC=C(Ph)C(=S)N(R)C(=NR)S (5a; R = Ph) which r esults from addition of a second isothiocyanate to the four-membered r ing of 3a. The reaction of 2 with PhCH2N=C=S at room temperature direc tly affords the six-membered-ring product 5b (R = CH2Ph). Trimerizatio n of phenyl isothiocyanate is catalyzed by Cp(dppe)RuC=CPh (1'; dppe = Ph2PCH2CH2PPh2) in refluxing CH2Cl2. This catalytic reaction proceeds through a pathway in which the first two steps are the same as those observed in the reaction of 2a. An attempt to purify the precursor of the trimerization product gave the cocrystallization of 1' and (PhNCS) (3) (8). The structures of 3a, 4a, 5b, and the cocrystallization produ ct of 1' and 8 have been determined by single-crystal X-ray diffractio n analysis.