1,5-Cyclooctadiene, complex with

In an ethanol solution of RhCl3, cis,irons-1,5-cyclodecadiene is converted to its cts,cis-l,6-isomer with subsequent formation of the dimeric rhodium complex [(l,6-CioHie)RhCl]2 which can also be prepared by direct interaction of the 1,6-olefin with RhCl3 in ethanol (579, 582). Spectral evidence suggests a configuration (192) much like that of the 1,5-cyclooctadiene complex with the 1,6-CioHie rings in a boat conformation. 

Square-planar Rh(I)-l,5-cyclooctadiene complexes with antitumor activity include 47-50. In these complexes, the bidentate cycloocta-... 

Catalytic Asymmetric Hydroboration. The hydroboration of olefins with catecholborane (an achiral hydroborating agent) is cataly2ed by cationic rhodium complexes with enantiomericaHy pure phosphines, eg, [Rh(cod)2]BE4BINAP, where cod is 1,5-cyclooctadiene and BINAP is... 

Photolytic reactions of dienes frequently give complex mixtures of rearranged products. Described here, however, is a photolytic isomerization of 1,5-cyclooctadiene (present in solution, in part, as a complex with cuprous chloride) that affords a good yield of one product. 

The synthetic route represents a classical ladder polymer synthesis a suitably substituted, open-chain precursor polymer is cyclized to a band structure in a polymer-analogous fashion. The first step here, formation of the polymeric, open-chain precursor structure, is AA-type coupling of a 2,5-dibromo-1,4-dibenzoyl-benzene derivative, by a Yamamoto-type aryl-aryl coupling. The reagent employed for dehalogenation, the nickel(0)/l,5-cyclooctadiene complex (Ni(COD)2), was used in stoichiometric amounts with co-reagents (2,2 -bipyridine and 1,5-cyclooctadiene), in dimethylacetamide or dimethylformamide as solvent. 

The neutral complexes [Au(C6F5)(PPhPy2)[ and [Au(CgF5)(PPy3)] were used to prepare the monocationic complexes [142] shown in Figure 3.22 by reaction with [Rh2( J--Cl2)L2] [L= 1,5-cyclooctadiene (COD), 5,6,7,8-tetrafluoro-l,4-ethenonaphtha-lene (TFB)]. The crystal structure of the complex with R = PPhPy2 and TFB as the diolefin was studied by X-ray diffraction. 

In 2004, Dieguez et al. reported the development of novel C2-symmetric dithioether ligands derived from the corresponding binaphthyl or biphenanthryl diols. Thus, various (i )-binaphthyl dithiols substituted by alkyl groups on the sulfur atom in order to increase the steric bulk were synthesised, and the corresponding mononuclear cationic Ir(I) -cyclooctadiene complexes were prepared and characterised (Scheme 8.20). NMR studies demonstrated that, in all cases, the coordination of the ligands proceeded with complete stereoselectivity at the... 

A remarkably stable, deep red Ni° stannylene complex, [Ni(1068)4l, has been prepared by the reaction of [Ni(l,5-cyclooctadiene)2] with (1068) in toluene at —78 °C. 70 In spite of the bulkiness of (1068) and the known tendency of analogous Ni° phosphine complexes to dissociate in solution, [Ni(1068)4] remains intact in solution and, moreover, melts at 178-180 °C without decomposition. X-ray crystallography shows tetrahedral geometry about the nickel atom, with Ni—Sn bond lengths of 2.3898(2)-2.399(2) A. 

In contrast to Ni, alkylpalladium precursors can be easily prepared and isolated owing to their greater stability (Scheme 2). The monomethyl chloride adducts of formula (diimine)PdMeCl can be conveniently synthesized via diimine displacement of other weakly coordinating ligands, such as COD from Pd(COD)MeCl (COD = 1,5-cyclooctadiene) [44], or by in situ alkylation-complexation with tetramethyltin [52], The chloride ligand can then be cleanly abstracted by metathesis with NaBAF... 

As mentioned earlier, preparation of (Z),( )-l, 5-cyclooctadiene (31) in an optically active modification 2) first demonstrated the chiral nature of ( )-cycloalkenes. In this classical experiment, Cope and coworkers obtained ( + )-31 by the Hofmann elimination of the (-l-)-ammonium salt 30. They were also successful in obtaining (+)-31 by optical resolution of racemic 31 through complexing with a chiral Pt(II)... 

The reverse process, in turn, is catalyzed by RhCl3, which preferentially forms a stable complex with 1,5-cyclooctadiene.197... 

Reactions of the HNiL3CN complex with 1,3-cyclopentadiene, 1,3-cyclo-hexadiene, and 1,3-cyclooctadiene gave intermediates with decreasing stabilities in that order the 1,3-cyclooctadiene intermediate was not spectroscopically observable. The cyclohexadiene adduct was shown to be the cyclohexadienyl complex 12 by its proton spectra, with resonances of H , Hb, and —(CH2)3— at 14.53, 6.06, and 8.47, respectively these values are close to the chemical shifts found earlier (51) for 13 14.52,5.86, and 8.48. The reaction of DNi[P(OMe)3]X with cyclopentadiene gives 13-d, with addition of D and Ni to the same side of the ring (52). Backvall and Andell (55) have shown, using Ni[P(OPh)3]4 and deuterium cyanide (DCN), that addition of D and CN to cyclohexadiene is stereospecifically cis, as expected for jt-allyl intermediate 12. 

In a different system, l-(trimethylsilyl)cycloocta-l,5-diene forms complexes with Ag(I), Rh(I), Pd(H) and Pt(II), in which the metals are pushed away from the Me3Si group267. The distortion in their structures, in comparison with the near-symmetrical structures of the corresponding 1,5-cyclooctadiene complexes, changes the characteristics of their 111 and 13 C NMR spectra. 

A number of compounds have been proposed as useful intermediates for the synthesis of ruthenium(II) complexes. Singleton and co-workers have investigated [Ru(diene) (N2H4)4]2+ in this respect. Reaction of the cyclooctadiene compound with bpy in acetone yields [Ru(cod)(bpy)2]2+ u8. With some ligands complete substitution resulted119. They later claimed120 [Ru(H)(cod)(NH2NMe2)3]+ to be the most versatile precursor known at that time. 

Coordination catalysts of formula (I), where M is Pd, Q is an alkyl, S is a halogen, R1 is H or an alkyl (1-4 carbon atoms), preferably a methyl group, and R2 is a hydrocarbyl (1-4 carbon atoms), preferably a methyl group, may be made by the reaction of the corresponding 1,5-cyclooctadiene (COD) Pd complex with the appropriate diimine. When M is Ni, (I) can be made by the displacement of another ligand, such as a dialkylether or a polyether such as 1,2-dimethoxyethane, by an appropriate diimine ... 

Complexes with alkenes and arenes are formed when the hydrocarbons are shaken with aqueous solutions of silver(I) salts. Di- or polyalkenes often give crystalline compounds with Ag+ bound to one to three double bonds. The formation of alkene complexes of varying stability may be used for the purification of alkenes, or for the separation of isomeric mixtures (e.g., 1,3-, 1,4-, and 1,5-cyclooctadienes), or of the optical isomers of a- and /3-pinene. There is very little back-bonding contribution in the formation of Ag1 rr-complexes. For example, the planar complex (hfa)Ag(Ph-C= C-Ph) contains an almost linear acetylene ligand with a C=C... 

Pentafluorophenylcopper tetramer is reported to form complexes with the 7T-bases 2-butyne and 1,5-cyclooctadiene (52). 

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