Cyclo-octadiene ligand

Hence, two methods are available that can be applied to follow nanoparticles formation and growth (i) an indirect method that utilizes the consumption of molecular hydrogen pressure versus time and (ii) a direct method that follows the loss of precursor by the 1 1 conversion of its cyclo-octadiene ligand to cyclo-octane by GLC measurements. The mechanism developed by Watzky and Finke suggests that the nanoparticles act as Hving-metal polymers -a concept that could be used to obtain particles with defined sizes simply by adding the appropriate amounts of catalyst precursors [32]. 

The cyclo-octadiene ligand in TpRuCl(COD) is substitutionally inert in this complex, in contrast to the analogous complexes CpRuCl(COD) and Cp RuCl (COD), requiring vigorous conditions to be applied. Thus, in boiling DMF, TpRuCl(COD) converts with L or L2 (e.g., mono- and bidentate A-, O- and P-donor ligands such as tertiary phosphines, tertiary phosphites, aminophosphines, amines, imines, DMSO, DMF) to TpRuCl(L2) and TpRuCl(L)2. ... 

The addition of 1 or 2 moles of phosphite ligand to the complex [Rh2( x-t-C4H9S)(C0)2 P(0CH3)3 2] does not displace the CO groups. To prepare the first complex, the special ability of the phosphite ligand, which does not cleave the chloro bridges in [Rh2(n.-Cl)2[Pg.123]

Another recent application to the activation of transition metals was reported (247) by Bonnemann, Bogdavovic, and co-workers, in which an extremely reactive Mg species was used to reduce metal salts in the presence of cyclopentadiene, 1,5-cyclo-octadiene, and other ligands to form their metal complexes. The reactive Mg species, characterized as Mg(THF)3 (anthracene), was produced from Mg powder in THF solutions containing a catalytic amount of anthracene by use of an ultrasonic cleaning bath. A plausible scheme for this reaction has been suggested ... 

In contrast, 1,5-cyclo-octadiene remains coordinated during the catalytic cycle of hydrogenation of phenylacetylene to styrene, catalyzed by the related iridium complex [Ir(C0D)( Pr2PCH2CH20Me)]BF4. This complex, which contains an ether-phosphine-chelated ligand, catalyzes the selective hydrogenation reaction via a dihydrido-cyclo-octadiene intermediate. The reaction is first order in each of catalyst, phenylacetylene and hydrogen [11] the proposed catalytic cycle is shown in Scheme 2.3. 

Abbreviations arene, i/6-benzene or substituted benzene derivative bipy, 2,2 -bipyridyl Bu, Bu", Bu, iso-, n-, or rerf-butyl COD, 1,5-cyclo-octadiene Cp, /5-C5H5 DAD, dimethyl-acetylene dicarboxylate dam, 1,2-bis(diphenylarsino)methane DBA, dibenzylideneacetone DMF, A. A -dimethylformamide dpe, l,2-bis(diphenylphosphino)ethane dpen, os-l,2-bis(di-phenylphosphino)ethylene dpm, 1,2-bis(diphenylphosphino)methane ESR, electron spin resonance F6-acac, hexafluoroacetylacetone FN, fumaronitrile MA, maleic anhydride Me, methyl MLCT, metal ligand charge transfer phen, 1,10-phenanthroline Pr , Pr", iso- or n-propyl py, pyridine RT, room temperature TCNE, tetracyanoethylene tetraphos, (Ph2PCH2CH2)jP THF, tctrahydrofuran Xylyl, 2,6-Me2C6H3. 

Diene and, especially cyclodiene complexes (together with arene compounds) are the most explored organometallic ligands. The above-mentioned method of direct (immediate) interaction of reactants is also used to prepare their complexes. As a source of metal center, PtCl2 (3.62) and K2[PtCl4] (3.63) are applied in reactions with cyclo-octadiene-1,5 (COD) [11] ... 

In both formed complexes, cyclo-octadiene-1,5 behaves as a chelate-forming 71,71-ligand 624 [75c, p. 94]. Reduction of 624 (M = Pt) (COD)PtCl2 in the presence of COD gives Pt(COD)2, which reacts with ethene to form Pt(C2H4)4 and PhC = CPh to yield Pt(C2Ph2)2 [74b] ... 

In butadiene di- and dimerization with nickel catalyst and (o-PhCd 1,0)3P as a stabilizing ligand, the yields of cyclo-octadiene and cyclo-dodecatriene... 

Ist der Ligand D jedoch ein zweizahniger -Donator wie 1-5-Cyclo-octadien, CsHi2, so erfolgt der Austausch nach einem SnI- und Ss2-Mechanismus (Tabelle 7 Nr. 4 u. 5). 

The 3H NMR spectrum of (191) shows that rotation about the C-N bond is fast on the NMR timescale even at —40°C.944 Variable-temperature H and 13C NMR spectra of cationic Ir(I) cyclo-octadiene complexes containing binaphthalene templated sulfide ligands show that in all cases the ligand chelation is stereoselective, and only one stereoisomer is produced 945... 

Sutherland have confirmed an earlier report about the dimerization of iso-prene over a nickel-based catalyst, and have additionally shown that the proportions of the products [(10), (11), and (12)] are 78 8 14, the cyclo-octadiene (10) being more than 98% head-to-tail linked. Some interesting reactions of the cyclo-octadiene (10) are described. Dimerization of isoprene with nickel-ligand... 

Hollaway et al. (11) also reported NMR data for a series of 1,5-cyclo-octadiene complexes of rhodium. The authors suggested that metal s orbital participation in Jrh-c may be small due to the large energy separation between the rhodium 5s and ligand donor orbitals. Consequently, small changes in the s orbital participation may have large effects on Jm-c-... 

Figure 9.7 Rhodium complex of the chiral ligand DIPAMP [Rh(l,5-cyclo-octadiene = COD)DIPAMP] (tetrafluoroborate).

Reactive nickel (Eq. 4), from nickel acetyl-acetonate and sodium, reacts in situ with 1,5-cyclo-octadiene to yield the Ni(COD)2 complexRuthenium chloride is reduced by zinc, and the metal reacts immediately with added ligands... 

The reaction of bis(cyclo-octa-l,3-diene)nickel with hexafluorobut-2-yne gives (cyclo-octadiene)nickel[(hexakistrifluoromethyl)benzene], (114) or (115), which decomposes slowly at room temperature. Other ligands can displace the cyclo-octadiene, and alternative routes to some of the compounds are also reported, including the novel displacement of ethylene from (Ph3P)2Ni(C2H4) by preformed hexakis(trifluoromethyl)benzene. The compounds are formulated either as formally five-co-ordinate nickel complexes, with the planar arene occupying three co-ordination positions and free... 

The application of Rh catalysts, which moved in the 1970s but in focus till today, allows operating the process under much milder conditions (20-120 bars, 70-160°C). Usually, the catalyst is produced from Rh(II)carboxylates, Rh(acac)(CO)2 (acac = acetylacetonate), or Rh(acac)(COD) (COD = 1,5-cyclo-octadiene). Commercial phosphorus ligands, such as monodentate phosphines (PPhg) or phosphites [P(OPh)3, P(0-o-tBuPh)3, Alkanox 240], significantly improve the activity. Simultaneously, isomerization of the starting olefin may occur. Commonly the ligand is used in an excess in comparison to the metal. 

Fig. 2.43. Reactions of [Fe2(CO)j ] with neutral species containing labile ligands (COD = 1,2-cyclo octadiene) [Tachikawa M, Geerts RL, Mueatterties EL (1981) J. Organoment. Chem. 213 11]...

T-Cyclopentadienyl-7c-l,5-cyclo-octadiene cobalt, (tc-C5H5)Co(C8Hi2), undergoes an exchange reaction in the presence of 2 moles of tolane (di-phenylacetylene). This reaction not only involves ligand exchange but also... 

T. V. Ashworth, M. J. Nolle, R. H. Reimann, and E. Singleton. Conversion of bonded cyclo-octadiene into a cyclo-octadienyl ligand and cleavage of boron-phenyl bonds of arenc-bonded tetraphenylborate anions in ruthenium(ii) systems X-ray crystal and molecular structures of [Ru(j -C H5BL3)(1-3,5,6-jj-C8Hii)] (L = Ph or F). J.C.S. Chem. Comm., 1977, 937. 

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