| Reaction of ((eta)-C(,5)H(,5))(,2)W(CH(,3))(,2) with NH(,4)I in THF allows convenient access to the valuable synthetic intermediate ((eta)-C(,5)H(,5))(,2)W(CH(,3))I . Treatment of this complex with PhMgBr results in the formation of ((eta)-C(,5)H(,5))(,2)W(CH(,3))C(,6)H(,5) which can be oxidized to ((eta)-C(,5)H(,5))(,2)W(CH(,3))C(,6)H(,5) PF(,6) (1) with either trityl or ferrocenium hexafluorophosphate. Reaction of 1 with trityl radical in acetonitrile results in the formation of ((eta)-C(,5)H(,5))(,2)W(CH(,2)C(,6)H(,5))(NCCH(,3)) PF(,6) (2), while the corresponding reaction in dichloromethane results in the formation of ((eta)-C(,5)H(,5))(,2)W(CH(,2)C(,6)H(,5))Cl PF(,6) (3) These two reactions are proposed to involve initial hydrogen atom abstraction from 1 to give ((eta)-C(,5)H(,5))(,2)W(CH(,2))C6H(,5) PF(,6). A subsequent (and unprecedented) migratory insertion of the electrophilic methylidene ligand into the tungsten-phenyl bond within this complex then generates a 16-electron tungstenocene-benzyl complex, which is trapped by a solvent molecule or a solvent derived atom. The identities of 2 and 3 have been confirmed by independent syntheses.; The electron rich complex ((eta)-C(,5)H(,5))(,2)W(CO) (4) readily reacts with a number of electrophilic organic heteroallenes to yield four-membered metallocyclic complexes derived from the formal 2+2 addition of a heteroallene double bond to the tungsten-carbonyl carbon bond. Thus, treatment of 4 with RNCO (R = CH(,3), Ph) results in the formation of ((eta)-C(,5)H(,5))(,2)W C(O)N(R)C(O) (5, R = CH(,3); 6, R = Ph), the first reported metallocycloimide complexes. Both 5 and 6 convert back to 4 when treated with an excess of water. Reaction of 4 with CH(,3)NCS, PhNCS, and PhNCNPh similarly gives ((eta)-C(,5)H(,5))(,2)W C(S)N(CH(,3))C(O) (7), ((eta)-C(,5)H(,5))(,2)W C(S)N(Ph)C(NPh) (8), and ((eta)-C(,5)H(,5))(,2)W C(O)N(Ph)C(NPh) (9), respectively; the X-ray crystal structures of 5 and 8 are reported.; Treatment of 4 with carbon tetrachloride results in the formation of the unusual mixed (eta)('5)-cyclopentadienyl/(eta)('4)-cyclopentadiene complex exo- ((eta)('5)-C(,5)H(,5))((eta)('4)-C(,5)H(,5)CCl(,3))W(CO)Cl ; the X-ray crystal structure of this species is also reported.; Oxidation of ((eta)-C(,5)H(,5))(,2)W(OCH(,3))CH(,3) (10) with ferrocenium hexafluorophosphate in methylethylketone results in the formation of the tungstenocene bridging-oxo complex ((eta)-C(,5)H(,5))(,2)W(CH(,3)) (,2)((mu)-O) PF(,6) (,2) (11). X-ray crystallography reveals the solid state structure of the cationic portion of 11 to consist of two ((eta)-C(,5)H(,5))(,2)W(CH(,3)) fragments centrosymmetrically linked by a bridging oxygen atom. Photolysis of 11 in acetonitrile produces a 1:1 mixture of ((eta)-C(,5)H(,5))(,2)W(NCCH(,3))CH(,3) PF(,6) (12) and ((eta)-C(,5)H(,5))(,2)W(O)CH(,3) PF(,6) (13), a rare example of a d('0) oxo-alkyl complex. In aerated acetone, photolysis of 11 produces exclusively 13, which can also be obtained by stirring an acetone solution of 12 in air. The X-ray crystal structure of 13 (as the I('-) salt) is reported. |
