Preparation, Structure, and Reactions of Triphenyl Phosphite Complexes of Iron, Ruthenium, and Osmium

A brief comparison of these 'H IVMR data to those spectral data of several nonmetalla-P-ketoimine analogues is warra~~ted.~JO For the N-phenyl, N-methyl, N-benzyl, and the unsubstituted acetylacetonimine molecules the NH resonances appear at 6 12.6 (CC14), 10.7 (CDC13), 11.2 (CDCl,), and 9.7 (CC14), respectively. The average values of the syn and anti NH resonances in CDC1, for the analogous metalla molecules 3, 6, 11, and 19 are 6 13.41, 11.44, 11.44, and 11.27, respectively. This lowering of the NH resonance along with the observation of benzylic coupling to the NH proton in Nbenzylacetylacetonimine may indicate a greater acidity (or localized positive charge) of the NH protons of the metalla-p-ketoimine molecules than for the organic analogues. This conclusion is consistent with the zwitterionic structures 3 and 4. However, the NH proton of the nonmetalla molecules (eg, N-benzylacetylacetonimine) also undergoes relatively facile deuterium e~change,~ and the electronic and magnetic influence of incorporating the rhenium atom directly into the P-ketoimine molecule is not well defined. It is also evident from the structure of complex 3 and the above 'H NMR data that the metalla-P-ketoimine molecules are quite different from the amino carbenoid complexes. The NH resonances of (OC)5Cr[C(CH3)(NHCH2C6H5)] and (OC)SCr[C(CH3)(NHC6Hs)]1' in CDC13 are 6 9.67 and 10.43, respectively. These values are 1.77 and 2.98 ppm to higher field than the average enolic NH resonances of the N-benzyl- and N-phenylmetallaacetylacetonimine complexes. Also, the NH proton of the N-benzyl carbenoid complex does not undergo deuterium exchange with methanol-d,. Complex 1 did not react with p-nitroaniline, (*)-aphenylethylamine, or (*)-a-tert-butylethylamine. Although the mechanism of the condensation reaction was not examined, if the condensation reaction is stopped prematurely, then a monoamine adduct of the metalla-P-diketone molecule can be isolated. The cyclohexylamine and isobutylamine adducts, 21 and 22, of complex 1 are crystalline solids which melt at slightly lower temperatures than the corresponding metalla-P-ketoimine molecules (AT = 8 and 14 OC, respectively). Although the structures of these adducts, which appear to be nonionic solids, are not known, they may be related structurally