Influence of the group 14 element on the deprotonation of OsH(eta(5)-C5H5)(C CPh)(EPh3)(PiPr(3)) (E = Si, Ge): Two different organometallic chemistries

The complexes OsH(eta (5)-C5H5)Cl(EPh3)((PPr3)-Pr-i) (E = Si (1), Ge (2)) r eact with lithium phenylacetylide to give the hydride-alkynyl derivatives O sH(eta (5)-C5H5)(C equivalent to CPh)(EPh3)(PPr3)-Pr-i) (E = Si (3), Ge (4) ). The structure of 4 has been determined by X-ray diffraction analysis. Th e distribution of ligands around the osmium atom can be described as a four -legged piano-stool geometry with the monodentate ligands lying in the four -membered face. Treatment of 3 with n-butyllithium and the subsequent addit ion of methanol, methanol-d(4), and methyl iodide to the resulting solution leads to OsH(eta (5)-C5H4SiPh3){=C=C(H)Ph}((PPr3)-Pr-i) (5), OsH(eta (5)-C 5H4SiPh3){=C=C(D)Ph}((PPr3)-Pr-i) (5-d), and OsH(eta (5)-C5H4SiPh3){o-C6H4C (CH3)=CH}((PPr3)-Pr-i) (6), respectively. Similarly to 3, the reaction of t he perdeuterated cyclopentadienyl complex OsH(eta (5)-C5D5)(C drop CPh)(SiP h3)(PiPr(3)) (3-d5) with n-butyllithium and methanol gives OsH(eta (5)-C5D4 SiPh3){=C=C(H)Ph}((PPr3)-Pr-i) (5-d(4)). The structure of 6 has been also d etermined by X-ray diffraction analysis. In this case, the distribution of ligands around the osmium atom can be described as a piano-stool geometry w ith the metalated carbon atom transoid to the phosphine and cisoid to the h ydride. Complex 5 reacts with HBF4 to give the hydride-carbyne derivative [ OsH(eta (5)-C5H4SiPh3){equivalent to CCH2Ph}((PPr3)-Pr-i)]BF4 (7), which is stable. Initially, the addition of HBF4 to diethyl ether solutions of 6 al so leads to a hydride-carbyne complex, [OsH(eta (5)-C5H4SiPh3){equivalent t o CCH(CH3)Ph}((PPr3)-Pr-i)]BF4 (8). However, in solution, complex 8 evolves into the hydride-allyl compound [OsH(eta (5)-C5H4SiPh3){eta (3)-CH2C(Ph)CH 2}((PPr3)-Pr-i)]BF4 (9). The structure of 9 has been determined by X-ray di ffraction analysis. The distribution of ligands around the osmium atom can be described as a piano-stool geometry, where the allyl ligand occupies two cisoid positions. Treatment of 4 with n-butyllithium and the subsequent ad dition of methanol, methanol-d4, and methyl iodide to the resulting solutio n gives the germyl-vinylidene complexes OS(eta (5)-C5H5)(GePh3){=C=C(H)Ph}( (PPr3)-Pr-i) (10), Os(eta (5)-C5H4D)(GePh3){=C=C(D)Ph}((PPr3)-Pr-i) (10-d(2 )), and Os(eta (5)-C5H4CH3)(GePh3){=C=C(CH3)Ph}((PPr3)-Pr-i) (11), respecti vely. The protonation of 10 and 11 with HBF4 affords the corresponding carb yne derivatives [Os(eta (5)-C5H5)(GePh3)(equivalent to CCH2Ph)((PPr3)-Pr-i) ]BF4 (12) and [Os(eta (5)-C5H4CH3)(GePh3){equivalent to CCH(CH3)Ph}((PPr3)- Pr-i)]BF4 (13).