SYNTHESIS AND REACTIVITY OF METAL ALPHA-HYDROXYALKYL COMPLEXES - GENERATION OF (CO)5MNCH(C6H5)OH, (CO)5RECH(C6H5)OH
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Reaction of (CO)5MnCOCOC6H5 with Li(C2H5)3BH gives the metallacycle Li+[(CO)4MnCOCH(C6H5)OC=O] (Li+-2), which upon treatment with [((C6H5)3P)2N]+Cl(PPN+Cl) gives PPN+-2. The structure of PPN+-2 is established by X-ray crystallography. Reaction of PPN+-2 or Li+-2 with (CH3)3SiCl and CF3S03H yields acyl complexes (CO)5MnC-OCH(C6H5)OSi(CH3)3(4) and (CO)5MnCOCH(C6H5)OH (5), respectively. Treatment of 4 with (CH3)3N+-O- gives -(silyloxy)alkyl complex (CO)5MnCH(C6H5)OSi(CH3)3(6). When 6 is treated with HC1 (78 to 50 C, 3 min), H20 (10 C, 2 h), or CH3OH (10 C, 3 h), or 5 is treated with (CH3)3N+-O (CO)5MnH and benzaldehyde form in a 1:1 ratio. These reactions are interpreted as proceeding via the a-hydroxyalkyl complex (CO)5MnCH(C6H5)OH (8). Similarly, reaction of (CO)5ReCOCOC6H5with Li(C2H5)3BH and then (CH3)3SiCl gives acyl complex (CO)5ReCOCH(C6H5)OSi(CH3)3(11). Reaction of 11 with H2O gives acyl complex (CO)5ReCOCH(C6H5)OH (12), and photolysis of 11 gives a-(silyloxy)alkyl complex (CO)5ReCH(C6H5)OSi(CH3)3(13). When 13 is treated with HF gas (-78 to 50 C) or H20 (25 C), or when 12 is photolyzed (-78 to 50 C), (CO)5ReH and benzaldehyde form in a 1:1 ratio. These reactions are interpreted as proceeding via the a-hydroxyalkyl complex (CO)5ReCH(C6H5)OH (14). When 13 is treated with HCl, (CO)5ReCH(C6H5)Cl (15) is obtained. Mechanisms for these transformations are proposed. 1986, American Chemical Society. All rights reserved.
