| Abstract
| - Several types of substituted cyclopentadienyl osmium(IV) complexes can be obtained byreaction of OsH(η5-C5H5)Cl(EPh3)(PiPr3) (E = Ge (1), Si (2)) with LiNu reagents. Both 1 and2 react with LiCH2CN. The reactions give OsH2(η5-C5H4EPh3)(CH2CN)(PiPr3) (E = Ge (3),Si (4)). The reaction of the perdeuterated cyclopentadienyl complex OsH(η5-C5D5)Cl(SiPh3)(PiPr3) (2-d5) with LiCH2CN affords Os(H)(D)(η5-C5D4SiPh3)(CH2CN)(PiPr3) (4-d5). Complex4 reacts with CD3OD to give OsH2(η5-C5H4SiPh3)(CD2CN)(PiPr3) (4-d2), which can be alsoobtained by addition of LiCD2CN to 2. The treatment of 1 with RLi leads to OsH2(η5-C5H4R)(GePh3)(PiPr3) (R = CH3 (5), nBu (6), secBu (7)). Under the same conditions, the additionof nBuLi to OsH(η5-C5D5)Cl(GePh3)(PiPr3) (1-d5) affords Os(H)(D)(η5-C5D4nBu)(GePh3)(PiPr3)(6-d5). Complex 2 also reacts with CH3Li and nBuLi. In both cases, complex (8) is obtained. The structure of 8 has been determined by X-raydiffraction analysis. The distribution of ligands around the metallic center can be describedas a four-legged piano stool geometry with the phosphine and the metalated phenyl groupmutually transoid. The treatment at room temperature of 2-d5 with nBuLi leads to a mixtureof (8-d4) and Os(H)(D)(η5-C5D4nBu)(SiPh3)(PiPr3) (9-d5) ina 2:1 molar ratio. The reaction of 2 with secBuLi also gives a mixture. In this case, it isformed by OsH2(η5-C5H4secBu)(SiPh3)(PiPr3) (10) and 8 in a 1:4 molar ratio. The addition ofLiCH2C(O)CH3 to 2 leads to (11). The reactions of 1 withLiNR2 afford OsH2(η5-C5H4NR2)(GePh3)(PiPr3) (R = Et (12), allyl (13)), while under the sameconditions 2 gives mixtures of 8 and OsH2(η5-C5H4NR2)(SiPh3)(PiPr3) (R = Et (14), allyl (15)).The structure of 13 has been also determined by X-ray diffraction analysis. The distributionof ligands around the metallic center is also a four-legged piano stool geometry, but in thiscase, the phosphine is transoid to GePh3. Both 1 and 2 react with LiPPh2. The reactionsgive the cyclopentadienyl phosphine derivatives OsH2(η5-C5H4PPh2)(EPh3)(PiPr3) (E =Ge (16), Si (17)).
- The reactions of OsH(η5-C5H5)Cl(EPh3)(PiPr3) (E = Ge, Si) with LiNu reagents can give rise to four different types of compounds: OsH2(η5-C5H4EPh3)(Nu)(PiPr3), OsH2(η5-C5H4Nu)(EPh3)(PiPr3), and The formation of these derivatives can be rationalized on the basis of the trend of the EPh3 and Nu ligands of OsH(η5-C5H5)(EPh3)(Nu)(PiPr3) for exchanging their positions with the hydrogen atoms of the cyclopentadienyl group and on the basis of the stability of these species and OsH2(η5-C5H4EPh3)(Nu)(PiPr3) toward the reductive elimination of H−Nu.
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