Mo(PMe3)6 cleaves a C-S bond of benzothiophene to give (κ2-CHCHC6H4S)Mo(PMe3)4, which rapidly isomerizes to the olefin-thiophenolate and 1-metallacyclopropene-thiophenolate complexes, (κ1,η2-CH2CHC6H4S)Mo(PMe3)3(η2-CH2PMe2) and (κ1,η2-CH2CC6H4S)Mo(PMe3)4. The latter two molecules result from a series of hydrogen transfers and are differentiated according to whether the termini of the organic fragments coordinate as olefin or η2-vinyl ligands, respectively. The reactions between Mo(PMe3)6 and selenophenes proceed differently from those of the corresponding thiophenes. For example, whereas Mo(PMe3)6 reacts with thiophene to give η5-thiophene and butadiene-thiolate complexes, (η5-C4H4S)Mo(PMe3)3 and (η5-C4H5S)Mo(PMe3)2(η2-CH2PMe2), selenophene affords the metallacyclopentadiene complex [(κ2-C4H4)Mo(PMe3)3(Se)]2[Mo(PMe3)4] in which the selenium has been completely abstracted from the selenophene moiety. Likewise, in addition to (κ1,η2-CH2CC6H4Se)Mo(PMe3)4 and (κ1,η2-CH2CHC6H4Se)Mo(PMe3)3(η2-CH2PMe2), which are counterparts of the species observed in the benzothiophene reaction, the reaction of Mo(PMe3)6 with benzoselenophene yields products resulting from C-C coupling, namely [κ2,η4-Se(C6H4)(CH)4(C6H4)Se]Mo(PMe3)2 and [μ-Se(C6H4)(CH)C(CH)2(C6H4)](μ-Se)[Mo(PMe3)2][Mo(PMe3)2H].
ASJC Scopus subject areas
- Colloid and Surface Chemistry