The reactions of 4,6-dimethyl-2-mercaptopyrimidine with dimetallic compounds: diiron nonacarbonyl and cyclopentadienylmolybedenum tricarbonyl dimer

Treatment of 4,6-dimethyl-2-mercaptopyrimidine with diiron nonacarbonyl at 25 °C in THF, gave two isomeric compounds, [(η2-μ1-C,NC6H7N2)Fe2(CO)6(μ4-S)Fe2(CO)6(μ2-SSC6H7N2)] (2) and (3). The X-ray structure analysis revealed that the cores of 2 and 3 are (μ4-S)Fe4 units with centered spirocyclic forms. On one side of the molecule, one diiron fragment is bridged by a pyrimidyl ligand through its nitrogen and carbon atoms; on the other side, the other diiron fragment is doubly bridged by a pyrimidinethiolate through its sulfur atom. Inter-conversion between 2 and 3 occurred rather slowly at 25 °C in solution; nevertheless, the rate was enhanced in the presence of high pressure of carbon monoxide. A major product, [(η2-μ1-C,NC6H7N2)Fe2(CO)6(μ4-S)Fe2(CO)5(P(OMe)3)(μ-SSC6H7N2)] (4), was obtained while 2 was treated with P(OMe)3 in THF at 25 °C for 24 h. In contrast, the reaction of 4,6-dimethyl-2-mercaptopyrimidine with cyclopentadienylmolybedenum tricarbonyl dimer in THF at 50 °C, gave an unimetallic complex, [(η5-C5H5)Mo(CO)2(η2-S,NSC6H7N2)] (5). Crystal structure of 5 revealed that the deprotonated mercaptopyrimidine acted as a bidentate ligand.