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Alkylidynes bridging

The reactivity of the alkylidyne-bridged binuclear species [(RCH2)2Ta]2(/i2-CR)2 ((22) R = SiMe3, (Scheme 4) towards a variety of 2,6-disubstituted phenols and mono- and di-substituted 1-napthyl phenols has been examined.66,67 For example, reaction with 2 eq ArOH = 2,6-But2-CgH3OH yielded the asymmetric 1,1-disubstituted species (RCH2)2Ta(/i2-CR)2Ta(OAr)2 (37). Silica-supported (22) catalyzed the hydrogenation of benzene and substituted benzenes.68... [Pg.248]

Alkyne either Inserts into the alkylidyne bridge of CFe2W(w2 CR) (u-CO)(C0)gCp3 (R = p-tol) to form a binuclear derivative or (e.g. alkyne = 02(811102)2 displaces two CO groups to form... [Pg.182]

Reactions of alkynes with trinuclear group 6-group 9 clusters incorporating bridging alkylidyne ligands proceeded by coupling the C-donor ligands. [Pg.72]

Byers, P.K, Carr, N. and Stone, F.G.A. (1990) Chemistry of polynuclear metal complexes with bridging carbene or carbyne ligands. Part 106. Synthesis and reactions of the alkylidyne complexes [M ( CR)(CO)2 (C6F5)AuC(pz)3 j (M = W or Mo, R — alkyl or aryl, pz — pyrazol-l-yl) crystal structure of pjC PtAu(C6F5)( l3-CMe)(CO)2(PMe2Ph)2 (C6F5)AuC(pz)3 ]. Journal of the Chemical Society, Dalton Transactions, (12), 3701—3708. [Pg.173]

We referred earlier to the significance of reactions at the alkylidyne carbon atoms of the dimetal species. Our studies in this area are in a preliminary stage, but Schemes 1 and 2 summarise some chemistry at the bridged carbon centres for the compounds (1 ) and (3,)(12). It will be noted that protonation of the neutral bridged al ylidyne compounds yields cationic alkylidene species in which one C—C bond of the tolyl group is n2 co-ordinated to tungsten, a feature revealed by both n.m.r. and X-ray diffraction studies. [Pg.371]

W=W triple bond and formation of both nitrido and alkylidyne complexes of WV1. Crystal structure determination94 of [(OBu )3W=N] and [(OBu )3W IMe]2 has shown that the nitrido complex is polymeric with unsymmetrical W—N—W bridges. The alkylidyne complex is dimeric with a short W—C bond length of 1.76 A. As expected, this distance is significantly shorter than the one observed for the W—C double bond. [Pg.982]

The structure of 11a has been established by X-ray diffraction. The compounds 11 are 30-cluster valence-electron (CVE) dimetal species, and are therefore electronically unsaturated. The electron distribution within the W(fi-C)fth rings may be represented by various canonical forms. However, that shown, which implies that the W=C bond in the ( 5-C2B9H9R 2)(OC)2-W=CC6H4Me-4 moiety formally contributes three electrons to the rhodium center (16-electron valence shell), accords with other results from our laboratory involving electronically unsaturated dimetal compounds with bridging alkylidyne ligands 18). [Pg.62]

As will be seen in later sections, the complexes in which the heteronuclear metal-metal bonds are bridged by agostic B—H—- metal interactions are intermediates in a variety of reactions involving the carbaborane cages and the /i-alkylidyne ligands. [Pg.70]

The firm identification of the alkylidyne group was particularly unexpected. These are almost certainly adsorbed on triangular 3-fold bridging sites on (111)... [Pg.52]

The general synthetic approaches for expanded porphycenes rely upon the insertion of alkylidene or alkylidyne moieties either as the meso-bridge or between the 2 and 2 positions of the bipyrrole subunits. Thus, the vinylogous dialdehyde 72 (Scheme 35) obtained from 4,4 -dipropyl-2,2 -bipyrrole with 3-(dimethyl-l-amino)acrolein has been converted to (1993PAC143) to 73 using a standard McMurry-type coupling. Expanded porphycene 73 with TFA precipitates as dication 74. [Pg.130]


See other pages where Alkylidynes bridging is mentioned: [Pg.120]    [Pg.35]    [Pg.167]    [Pg.2968]    [Pg.167]    [Pg.82]    [Pg.84]    [Pg.163]    [Pg.287]    [Pg.27]    [Pg.160]    [Pg.180]    [Pg.325]    [Pg.334]    [Pg.336]    [Pg.120]    [Pg.35]    [Pg.167]    [Pg.2968]    [Pg.167]    [Pg.82]    [Pg.84]    [Pg.163]    [Pg.287]    [Pg.27]    [Pg.160]    [Pg.180]    [Pg.325]    [Pg.334]    [Pg.336]    [Pg.169]    [Pg.73]    [Pg.204]    [Pg.220]    [Pg.250]    [Pg.152]    [Pg.227]    [Pg.361]    [Pg.143]    [Pg.126]    [Pg.126]    [Pg.65]    [Pg.162]    [Pg.70]    [Pg.87]    [Pg.376]    [Pg.380]    [Pg.96]    [Pg.81]    [Pg.102]    [Pg.113]    [Pg.121]   
See also in sourсe #XX -- [ Pg.108 , Pg.116 ]




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Alkylidyne

Alkylidyne ligand bridging

Alkylidynes

Bridging alkylidene and alkylidyne

Cluster bridging alkylidyne ligand

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