Formation of cationic molybdenum η²-vinyl complexes; structural evidence for the coupling of η²-vinyl and alkyne ligands

Abstract

Protonation (HBFd.Et20) of [ M O X ( ~~-M ~C ~M ~) ~L ] (X = CI, Br, I; L = q-C5H5 or q5-C9H7) affords the cations [XM-HMe(q2-MeC2Me)Ll [BF41, which react with LiX to give [X2klo=C(Me)~HMe(q2-MeC2Me)L] or with PR3 (R = Me, or OMe) to give the C-C coupled products [XMo=C(Me)-q3-{C(Me)C(Me)CHMe}(PR3) (L)][BF4], the latter being structurally identified by X-ray crystallography; carbon-carbon coupling also occurs on reduction of [Br2M-HMe(q2-MeC2Me)(q-C5H5)] with Mg/Hg in the presence of CO to form [MoBr(CO){q4-CHMe=C-(Me).C(Me)=CHMe}(q-C5H5)l, and treatment of the phosphine promoted coupled products with Li[N(SiMe3)2] leads to reversible deprotonation reactions affording [MoX{q4-CHMe=C(Me).C(Me)=C=CH2}(PR3)L].

Reactions of co-ordinated ligands. Part 55. Molybdenummediated addition of alkynes to cyclooctatetraene; one-electron oxidation and protonation of η3-allyl(η4-1,3-diene)(η-cyclopentadienyl or η5-indenyl) molybdenum complexes, and crystal structures of [Mo(η3,η4-C12H13)(η-C5H5)], [Mo(η2,η4-C14H17)(η-C5H5)][BF4] and [Mo(η2,η

“…2.315(7) A. The bonds Mo-C( 12) and Mo-C( 13) have lengthened by smaller amounts to 2.3 lO(7) and 2.288(6) A respectively, increases of 0.065(9) and 0.023 (9) A by comparison with the neutral complex 1. The carbon-carbon bond distances within the allyl are reduced; C(llbC(12) is 1.343(11) A, a reduction of 0.057( 14) A compared to that in 1, and C(12)-C(13) is 1.391(10) A, a reduction of 0.030( 14) A.…”

Reaction Chemistry of the Carbenoid Butadienyl Complex Ion [CpCo(σ,η4‐C4HMe4)]+ Formed by Protonation of the Cyclobutadiene Complex [CpCo(C4Me4)]

“…Marked C-H acidity at a carbon atom ß to a carbene center is well known for Fischer carbene complexes, [13] and has previously been observed for some of the known σ,η 4 -butadienyl complexes. [10,14] When 3 + was deprotonated with NEt 3 in a 1:1 ratio, i.e. under conditions where a low proton activity is retained, some unidentified solid material was deposited.…”

Deprotonation of η2(4e)-bonded alkynes as a pathway to σ,η2(3e)-prop-2-ynyl, η5-pentadienyl and η4-trans-1,3-diene substituted molybdenum complexes

“…Addition of diethyl ether afforded orange crystals of the cationic complex 12. Surprisingly, the IR spectrum of 12 showed no evidence for the presence of a co- 0.617 6 ( 5 ) 0.699 6 ( 5 ) 0.673 l ( 5 ) 0.564 5(5) 0.482 4( 5 A single-crystal X-ray diffraction study with the cationic complex 12 established the solid-state structure illustrated in Fig. 11, fractional coordinates and selected bond lengths and angles being listed in Tables 10 and 11 respectively.…”