Cyclo-octa-1,5-diene complexes, with

The insoluble complexes (27) have been prepared by the room-temperature reaction of the appropriate cyclo-octa-1.5-diene cuprous halide dimer with [(Tt-CpljTilSR),], in toluene, under an atmosphere of nitrogen. The existence of a Ti—Cu bond is suggested from comparative spectral studies with [(7t-Cp)2-... 

The above type of bonding is assumed to occur in other metal-olefin and metal-acetylene complexes (172). Acetylenes have two mutually perpendicular sets of ir-orbitals and are therefore capable of being bonded to one or to two metal atoms both types of complexes are known. When the hydrocarbon is a nonconjugated polyolefin e.g., cyclo-octa-1,5-diene, each C C bond interacts independently with the metal atom. In complexes of conjugated polyolefins, e.g., cyclopentadiene, infrared and nuclear magnetic resonance studies (99) indicate that it is not yet possible to distinguish between structure (IV), in which each C C bond independently contributes two --electrons to the metal-olefin bonding, and structure (V), in which... 

Dienes react with molybdenum hexacarbonyl to give complexes of the type [Mo(CO)4(diene)] and [Mo(CO)2(diene)2], which are generally yellow, soluble in organic solvents, and readily sublimed. Cyclo-octa-1,5-diene (12, 79, 151), bicyclo[2,2,l]hepta-2,5-diene (175), a dimer of cyclo-octa-tetraene (12) and dimethyldivinylsilane (158) give the former type of complex with the structure (VI M = Mo), while butadiene (81) and cyclo-hexa-1,3-diene form the latter type (80). Tetracyclone gives the complex [Mo(CO)2(tetracyclone)2] (215). 

Diene complexes of the type [W(CO)4(diene)l (VI M = W) are formed by cyclo-octa-1,5-diene (79, 151), hexa-1,5-diene (151), and dimethyldi-vinylsilane (158) on heating with tungsten hexacarbonyl. Cycloheptatriene (158) displaces cyclo-octa-1,5-diene and 1 mol. of carbon monoxide from its tungsten complex ... 

Treatment of tungsten hexacarbonyl with a mixture of cyclo-octa-1,3,5-and -1,3,6-triene gives the complex [W(OO iCslIiohJ (85). The hydrocarbon is believed to be the 1,3,6-triene, acting as a diene, but for the reasons mentioned (see Section III,H) it is possible that the ligand is bicyclo[4,2,0]-octa-2,4-diene (XV). 

The strongly chelating dienes bicyclo[2,2,l]hepta-2,5-diene (1) and cyclo-octa-1,5-diene (12) react with ruthenium halides to give stable, diamagnetic complexes of the composition [RuX2(diene)] (X = Cl, Br, I). Note added in proof. 

Osmium (IV) does not react with ethylene under pressure (97), or with cyclo-octa-1,5-diene (45), but the osmium(II) complex [Os2Cl3(PEtPh2)6]Cl gives the stable, 6-coordinated complex [OsCUfPEtPl MCsHu)] on treatment with cyclo-octa-1,5-diene, which acts as a chelating ligand in the complex (40a). 

Treatment of the complex (XXVII X = Cl) with acetylacetone (acacH) in alkali gives the mononuclear a-acetylacetonyl compound [Rh(acac)(C8Hi2)]. The stable, diamagnetic complex cyclo-octa-l,5-dicne-cyclopentadienylrhodium(I), [Rh(C6H6) (CgH )], is formed from the dimer (XXVII X = Cl) and cyclopentadienyl sodium (44, 45). The analogous complex, with cyclopentadiene as the chelating diene, has been prepared in 1-2% yield (91) by the reaction ... 

No complex was obtained on treatment of iridium (III) chloride with ethylene (67, 97, 138) or cyclo-octa-1,5-diene (45), but the ethylene complex [IrCl2(C2H4)] was reported to be formed by the action of ethanol on iridium chloride (67,138). No further examination of this complex has been reported. 

Anhydrous silver-olefin complexes are readily dissociable, low-melting, and variable in composition 92a, 176, 183). Cyclic olefins and polyolefins form stable complexes with silver nitrate or perchlorate, but again the Stoichiometry of the complexes varies considerably, sometimes depending on the conditions of preparation. The following types have been isolated [Ag(un)2]X (un = e.g., cyclohexene, a- and /3-pinene) ISO), [Ag(diene)]X diene = e.g., dicyclopentadiene 220), cyclo-octa-1,5-diene 50, 130), bi-cyclop, 2,1 ]hepta-2,5-diene 207), and cyclo-octa-1,3,5-triene 52), and [Ag2(diene)]X2 (diene = e.g., cyclo-octa-1,3- and -1,4-diene 180), bi-cyclo[2,2,l]hepta-2,5-diene 1) and tricyclo[4,2,2,0]-decatriene 10)). Cyclo-octatetraene (cot) forms three adducts with silver nitrate 52), viz., [Ag(cot)]NOs, [Ag(cot)2]N03, and [Ag3(cot)2](N03)3. On heating, the first two lose cyclo-octatetraene and all three decompose at the same temperature. From the stoichiometry of the above complexes it appears that the... 

CO)3] (R = H or Pz) complexes via carbonylation of [Rh(RBPz3](L L)] (L-L = C2H4 cyclo-octa-1,5-diene) substrates.146 Oxidation of this product with iodine in dichloromethane yielded the deep red Rh111 derivative [Rh(RBPz3)I2(CO)], which n.m.r. evidence showed to be an (i3-polypyrazolylborate complex. 

Higher 43-hydrocarbyl derivatives of transition metals can be obtained by partial protolysis of the bis(7i-allyl)metal compounds formed from cyclo-octa-1,5-diene metal complexes and 1,3-butadiene with one equivalent of the Bronsted acid in the presence of the proper ligand in a polar solvent at lowered temperature (e.g. — 40°C). For instance, Ni [43-(CxHn)l and Ni—[43-(Ci2Hig)] derivatives have been yielded by the reaction of Ni(CxH 2)2 [(Ni(Cod)2] with 1,3-butadiene (C4H6), followed by treatment with a Bronsted acid, according to scheme (1) [132] and scheme (2) [37] respectively ... 

A serendipitous discovery(6) that [Pt(cod)2] (cod cyclo-octa-1,5-diene) reacted with perfluoropropene to give the diplatinum complex [pt2 y-C(CF3)2 (cod)2], rather than the simple Ti2 adduct [Pt(CF2 CFCF3)(cod)], led to the idea(7) that mononuclear metal-carbene or -carbyne complexes would combine with nucleophilic and co-ordinatively unsaturated metal species (M") ... 

Olefinic complexes of copper have been reviewed in Volume 12 of this series (289). Since the appearance of this review, [Cu(cycloocta-l,6-diene)2]BF4 has been prepared by electrolysis of Cu(BP4)2 in methanolic diolefin at copper electrodes (231). Complexes (cycloocta-l,5-diene)Cu02C-CPg, (cyclooctatetrene)(Cu02C CPa)2, and (cyclo-octa-l,5-diene)(Cu02C CF3)a have been obtained as white or pale yellow solids by reacting CuOaC -CFg with the olefins in pentane or benzene, respectively (107). The structure of Cu2Gl2(trans-cyclooctene)3 (Fig. 10) has been determined (124) and is reminiscent of the structure of Cu2Cl2(PPh3)3 (Fig. 5). 

Perhaps the most useful of the r 3 allyl complexes (cf. 24) are the Jt-allyls of nickel.15 The simplest type 61 are rather unstable and form the bromide-bridged complex 62 on treatment with HBr. These are stable compounds officially complexes of Ni(I) but better regarded for our purpose as dimers of r 3 complexes of allyl anions and Ni(II), much as allyl Grignard reagents 2 can be regarded as o-complexes of allyl anions and Mg(II). Direct exchange of Mg(II) for Ni(II) gives the unstable complexes 61, but the stable dimer 62 can be made by oxidative insertion of Ni(0), as its cyclo-octa-1,5-diene (COD) complex, into allyl bromide 1. 

The formation of an complex has also been proposed to occur in the solid-liquid hydrogenation of alkenes with the supported hydrogen-bonded (SHB) catalyst [(sulphos)Rh(cod)]/Si02 (sulphos = 03S(C6H4)CH2C(CH2PPh2)3 cod = cyclo-octa-1,5-diene) (Scheme 10) [55-56]. 

Polymeric-ruthenium catalysts have been prepared by the reaction of ( / -cyclo-octa-l,3,5-triene) (// -cycloocta-1,5-diene) ruthenium(0), (// -cydoocta-l,3,5-triene) (COT) (// -cycloocta-1,5-diene) (COD) with polystyrene in hydrogen at room temperature [258]. Elemental analysis, IR and mass-spectrometry data show that in these polymer-metal complexes, two cycloolefin ligands, present in the starting Ru(COT)(COD) complex, are substituted by two phenyl rings of polystyrene ... 

Treatment of 5,8-bis(trimethylsilyl)cyclo-octa-l,3,6-triene or 3,5,8-tris(trimethyl-silyl)cyclo-octa-l,3,6-triene with triruthenium dodecacarbonyl gave the pentalene complexes (352 X = H or SiMe ). Tricarbonyl(Ti-cyclo-octa-l,5-diene)ruthenium and tricarbonyl(T)-cyclo-octa-l,3-diene)osmium have been prepared. They react with trityl fluoroborate to give cyclo-octadienylium complexes [(CgHn)M(CO)3] which react with anionic nucleophiles to give neutral compounds, some of which... 

When di-p-chloro- and di-p-methoxidobis(2-methoxycyclo-oct-5-enyI)dipallad-ium(ii) were refluxed in methanol with and without added base, and when dichloro-(cyclo-octa-l,5-diene)palladium(ii) was refluxed in methanol with added base, complex mixtures of products were obtained comprising cyclo-oct-4-enyl methyl ether, cyclo-oct-4-enone, and cyclo-octa-2,4-, -2,5-, -3,5-, and -1,5-dienyl methyl ethers. 

The 1 1 complex derived from phenyltungsten trichloride and aluminium trichloride is an effective catalyst for diene-cyclobutane metathetical interconversions. Thus, the tetracyclic compounds (291) and (292) were respectively isomerized to the dienes (293) and (294). Rather more surprising was the virtually quantitative formation of the cyclobutanoid compound (296) from (295). Reaction of norbomadiene with 2,2 -bipyridyl(cyclo-octa-l,5-diene)nickel at 25°C yielded the exo-trans,endo-metal o-carbocyclic (297) which, on treatment with an activated olefin (e.g. maleic anhydride), afforded the cyclo-dimer (298 predominantly exo-trans,endo) in good yield by displacement of the hydrocarbon moiety. Catalytic conversions can also be achieved. 

Although synthetic routes using Ru(II) arene dimers can give high yields of relatively pure half-sandwich products, they are limited by the availability of suitable precursor dienes. Alternative routes involve, for example, substitution of weakly bound naphthalene in the Ru(0) complex [(ri -naphthalene)Ru(Ti -COD)] (where COD is cyclo-octa-1,5-diene) by an added arene [38] followed by conversion to the Ru(II) arene dimer on addition of HCl [39]. This pathway can provide access to Ru(I I) arene complexes with functional side-chains on the arene [40]. Other routes involve thermal displacement of coordinated p-cymene by sterically-demanding arenes such as hexamefhylbenzene [41], photoinduced substitution ofe.g. benzene in [(ri -benzene)Ru(amidinate)(Cl)] [42], derivatization of coordinated arenes in [(ri -arene)Ru(Cp)] complexes [43], and stoichiometric cyclotrimerization of alkynes using [(ri -naphthalene)Ru(r -COD)] [44, 45]. It is also possible to synthesize mono- and bis-arene Ru(II) complexes starting from [Ru(II)(H20)g] which can aromatize cyclic olefins when heated in water or other suitable protic solvents [46, 47]. 

Hexafluorobut-2-yne adds to the 1,4-positions of the rhodiunv-acetyl-acetonate ring of acetylacetonato(cyclo-octa-l,5-diene)rhodium, and this adduct reacts with hexakis(trifluoromethyl)benzene, formed in situ, to give complex (86a), in which the cyclo-octadiene has been displaced. This structure is confirmed by single-crystal A -ray diffraction. The same product is formed from the corresponding (hexachloronorbomadiene)rhodium complex, but with acetylacetonatobis(ethylene)rhodium or the (ethylene)-(tetrafluoToethylene)rhodium complex, the cyclohexadiene complex (87), in which the one molecule of ethylene is incorporated into the co-ordinated... 

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