Preparation, characterization, and reactivity studies of chelated substituted cyclopentadienylmanganesedicarbonyl complexes

Article abstract of DOI:10.1016/S0022-328X(96)06458-3

Chelates of the parent compounds (η⁵-C₅H₄C(O)CH₂OCH₃)Mn(CO)₃ (1), (η⁵-C₅H₄C(O)CH₂SCH₃)Mn(CO)₃ (2), (η⁵-C₅H₄C(O)CH₂CH₂SCH₃)Mn(CO)₃ (3), (η⁵-C₅H₄CH₂COOCH₃)Mn(CO)₃ (4), and (η⁵-C₅H₄CH₂CH₂COOCH₃)Mn(CO)₃ (5) were prepared by photolysis. Only the chelates (η¹:η ⁵-C ₅ H ₄C(O)CH ₂SCH ₃)Mn(CO)₂ (2chelate) and (η ¹:η ⁵-C₅H₄C(O)CH₂CH₂SCH₃)Mn(CO)₂ (3chelate) were stable enough to be isolated. The X-ray structure of 2chelate was determined and demonstrated ring strain in the chelate ring. Derivatives of the chelates were obtained by thermal substitution of the chelated group. Substitution of the chelated groups in (η¹:η⁵-C₅H₄C(O)CH₂OCH ₃)Mn(CO)₂ (1chelate), (η¹:η⁵-C₅H₄CH₂COOCH ₃)Mn(CO)₂ (4chelate), and (η¹:η⁵-C₅H₄CH₂CH₂COOCH₃)Mn(CO)₂ (5chelate) occurred within a few minutes, whereas 2chelate and 3chelate required refluxing for several hours to convert them to the substituted products. The substituted products have the general formula (η⁵-C₅H₅R)Mn(CO)₂L (where R is the substituent of either 1-5 and L is either a phosphine, phosphite, or tetrahydrothiophene). The weaker Mn-O bond was suggested for the differences in the reactivities of the chelated complexes.