SYNTHESES AND REACTIONS OF CATIONIC CYCLIC (GAMMA-HYDROXYPROPYL)MOLYBDENUM(IV) DERIVATIVES - NEW PATHWAY FOR MOLYBDENAOXACYCLOPENTANES

The reaction Of CP2MoH2 (Cp = eta5-C5H5) with CH2=C(R1)C(R2)2OH (R1 = R2 = H; R1 = H, R2 = CH3; R1 = CH3, R2 = H) in the presence of TsOH (p-CH3C6H4SO3H) afforded [Cp2MoCH2CH(R1)C(R2)2OH]+TsO- (3). In the case of allyl alcohol, the reaction was accompanied by the formation of [Cp2Mo(eta3-allyl)]+TsO- (5). A higher ratio of 3/5 in the product mixture was obtained by employing a stronger protonic acid such as gaseous HCI. Complexes 3 were deprotonated by treatment with NaOH in ethanol to give the neutral oxametallacycle Cp2MoCH2CH(R1)C(R2)2O (4). On protonation with TsOH, 4 reverted to 3, whereas alkylation at the oxygen atom of 4 with RI (R = CH3, C2H5) yielded the corresponding cationic complexes [Cp2MoCH2CH(R1)C(R2)2OR]+I- (6). A possible reaction pathway for the formation of 3 and 5 was discussed with special reference to the product selectivity.