SYNTHESIS AND REACTIVITY OF STABLE METALLACYCLIC MANGANESE AND RHENIUM ALPHA-HYDROXYALKYL COMPLEXES OF THE FORMULA (CO)4MP(C6H5)2(ORTHO-C6H4CHOH)
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Reaction of (CO)5ReCH2C6H5 with (C6H5)2P(o-C6H4OSi(CH3)2(t-C4H9)) in octane (100126 C) gives the metallacycle (CO)4Rep(C6H5)2(o-C6H4CHOSi(CH3)2(t-C4H9)) (21,46%). Reaction of 21 with (C2H5)4N+F-(H2O)2.6, followed by silica gel filtration, gives the stable a-hydroxyalkyl complex (CO)4ReP(C6H5)2(o-C6H4CHOH) (5, 77%). When this reaction is worked up prior to silica gel filtration, crystalline metallabicycle (C2H5)4N+-fac-[(CO)3ReP(C6H5)2(o-C6H4C(H)OC=O)]-(22, 94%) is isolated. The structure of 22 is established by X-ray crystallography. Complex 5 can also be prepared by reduction of (CO)4ReP(C6H5)2(o-C6H4C=O) (24) with BH3THF (93%). Depending upon conditions, CF3S03H converts 5 either to the ether [(CO)4ReP(C6H5)2(o-C6H4CH)-]2O (23) or an ca. 1:1 mixture of 24 and (CO)4ReP(C6H5)2(o-C6H4CH2) (25). Reaction of (CO)5MH, M = Re, with (C6H5)2P(o-C6H4CHO) (18) does not give 5, but when M = Mn, (CO)4MnP-(C6H5)2(o-C6H4CHOH) (4, 75-84%) is obtained. On the basis of these data and results of other researchers, it is suggested that many of the factors that influence the stability of organic XCH(R)OH compounds (e.g., hemiacetals) also influence the stability of LnMCH(R)OH complexes. Complexes 4 and 5 do not carbonylate under 300 psi of CO. Reaction of (CO)5-MnSi(CH3)3 with 18 gives (CO)4MnP(C6H5)2(o-C6H4CH(OSi(CH3)3)C=O) (29, 52%), which upon subsequent treatment with KF gives an authentic sample of carbonylated 4, hydroxyacyl complex (CO)4MnP(C6H5)2(o-C6H4CH(OH)C=O) (30, 93%). 1986, American Chemical Society. All rights reserved.