Generation of functionally substituted cyclopentadienyl ligands in osmium(IV) chemistry

Several types of substituted cyclopentadienyl osmium(IV) complexes can be o btained by reaction of OsH(eta (5)-C5H5)Cl(EPh3)((PPr3)-Pr-i) (E = Ge (1), Si (2)) with LiNu reagents. Both 1 and 2 react with LiCH2CN. The reactions give OsH2(eta (5)-C5H4EPh3)(CH2CN)((PPr3)-Pr-i) (E = Ge (3), Si (4)). The r eaction of the perdeuterated cyclopentadienyl complex OsH(eta (5)-C5D5)Cl(S iPh3)((PPr3)-Pr-i) (2-d(5)) with LiCH2CN affords: Os(H)(D)(eta (5)-C5D4SiPh 3)(CH2CN)((PPr3)-Pr-i) (4-d(5)). Complex 4 reacts with CD3OD to give OsH2(e ta (5)-C5H4SiPh3)(CD2CN)((PPr3)-Pr-i) (4-d(2)), which can be also obtained by addition of LiCD2CN to 2. The treatment of 1 with RLi leads to OsH2(eta (C5H4R)-C-5)(GePh3)((PPr3)-Pr-i) (R = CH3 (5), Bu-n (6), Bu-sec (7)). Under the same conditions, the addition of (BuLi)-Bu-n to OsH(eta (5)-C5D5)Cl(Ge Ph3)((PPr3)-Pr-i) (1-d(5)) affords Os(H)(D)(eta (5)-(C5D4Bu)-Bu-n)(GePh3)(( PPr3)-Pr-i) (6-d(5)). Complex 2 also reacts with CH3Li and (BuLi)-Bu-n. In both cases, complex OsH2{eta (5)-C5H4-Si(C6H4Ph2}((PPr3)-Pr-i) (8) is obtai ned. The structure of 8 has been determined by X-ray diffraction analysis. The distribution of ligands around the metallic center can be described as a four-legged piano stool geometry with the phosphine and the metalated phe nyl group mutually transoid. The treatment at room temperature of 2-d(5) wi th (BuLi)-Bu-n leads to a mixture of OsH2(eta (5)-C5D4Si(C6H4)Ph-2}((PPr3)- Pr-i) (8-d(4)) and Os(H)(D)(eta (5)-(C5D4Bu)-Bu-n)(SiPh3)((PPr3)-Pr-i) (9-d (5)) in a 2:1 molar ratio; The reaction of 2 with (BuLi)-Bu-sec also gives a mixture. In this case, it is formed by OsH2(eta (5)-(C5H4Bu)-Bu-sec)(SiPh 3)((PPr3)-Pr-i) (10) and 8 in a 1:4 molar ratio. The addition of LiCH2C(O)C H3 to 2 leads to OsH(eta (5)-C5H5)(SiPh2C6H4)((PPr3)-Pr-i) (11) The reactio ns of 1 with LiNR2 afford OsH2(eta (5)-C5H4NR2)(GePh3)((PPr3)-Pr-i) (R = Et (12), allyl (13)), while under the same conditions 2 gives mixtures of 8 a nd OsH2(eta (5)-C5H4NR2)(SiPh3)((PPr3)-Pr-i) (R = Et (14), allyl (15)). The structure of 13 has been also determined by X-ray diffraction analysis. Th e distribution of ligands around-the metallic center is also a four-legged piano stool geometry, but in this case, the phosphine is transoid to GePh3, Both 1 and 2 react with LiPPh2. The reactions give the cyclopentadienyl phosphine derivatives OsH2(eta (5)- C5H4PPh2)(EPh3)((PPr3)-Pr-i) (E = Ge (16), Si (17)).