Arene Carbonyl Complexes

The first example of a 1,3-dienetetracarbonylchromium complex, butadienetetracarbonylchromium, has been prepared by condensing chromium atoms with butadiene and subsequent treatment with CO. The compound has been characterized by mass, i.r., and n.m.r. spectral studies.  

The reactions of 5-acetyl-1,2,3,4,5-pentamethylcyclopentadiene with metal carbonyls provide a convenient route to various pentamethylcyclopentadienyl metal carbonyl derivatives. Thus, [CrfCO) ] and MejCjAc give [ MejCjCr-(00)2)2] iu boiling 2,2,5-trimethylhexane. The crystal structure of 

Glass and T. Shiels, Inorg. Nuclear Chem. Letters, 1972,8, 257. 

The crystal structures of (3a,4-8,8a-f/)-[5.7,8-trimethyl-8H-cyclohepta-(fe)-thiophen]- and (1—3,3a.8a-f7)-[5,7-dimethyl-4//-cyclohepta-(c)-thiophen]-chromium tricarbonyl complexes, (55) and (56). respectively, have been determined.  

The crystal structure of tricarbonyl-(2,4,6-triphenylphosphorin)chromium (57) has been reported. The Cr(CO)3 group has a central position above the 

An interesting case of fluxional behaviour of a benzene ligand on the surface of a trimetallic osmium cluster has been observed for [Os3(CO)8(ti -C2H4)(p3,t), ti, ti -C6H6)] [51]. The motion is described as a ring jumping between discrete nuclear sites with minimum potential rather than as a hindered rotation when intermediate orientations might be populated for 

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The only description of (rj-arene)carbonyl complexes of Ti, Zr, and Hf has again been in the patent literature. Ethyl Corporation reported the preparation of (T/-C6H6)Ti(CO)3 via the carbonylation of TiPh2Cl2 (116). 

Closely related to these arene carbonyl complexes are the cycloheptatriene derivatives, which, however, are prepared by insertion of C7H8 into a Re-C bond followed by H abstraction, with Ph3C+, as shown in Scheme 32. 

Arene-carbonyl complexes such as [M(arene)(CO)3] are very resistant to oxidation. This is due to acceptor properties of the CO groups which cause the increase of the positive charge on the metal. Few cases of oxidation of complexes of the type [M(arene)(CO)3] are known however, in these cases, the coordination number increases. 

Bis ( -arene) metal complexes have been made for many transition metals by the AI/AICI3 reduction method and cationic species [M( j -Ar)2]"" " are also well established for n = 1, 2, and 3. Numerous arenas besides benzene have been used, the next most common being l,3,5-Mc3C6H3 (mesitylene) and CeMce. Reaction of arenas with metal carbonyls in high-boiling solvents or under the influence of ultraviolet light results in the displacement of 3CO and the formation of arena-metal carbonyls ... 

XI. Group 4B Carbonyl Complexes Containing rj-Arene Rings. 375... 

GROUP 4B CARBONYL COMPLEXES CONTAINING tj-ARENE RINGS... 

Mixed Carbonyl-Cyclopentadienyl and Carbonyl-Arene Metal Complexes.142... 

The only example of P.E. spectra of a mixed arene-carbonyl metal complex is that of Cr(bz)(CO)3 reported by Guest et al. (76). In the latter compound, the two d-bands observed in the spectrum of Cr(bz)2 merge into a single band, with maximum at 7.42 eV, containing the ionizations of all six -electrons. A second band, at 10.70 eV, is related to a benzene orbital, while a third band, at 12.70 eV, has both carbonyl and benzene character. The assignment is supported by theoretical calculations and by comparison between He(I) and He(II) spectra (76). 

The behavior shown in Schemes 2.22 and 2.23 suggests that these hydrido arene-iridium complexes might act as hydrogenation catalysts. Thus, the [(T -C6H6)IrH2(P Pr3)]BF4 complex has been shown to be an efficient hydrogenation catalysts for alkenes and alkynes, as well as some carbonyl groups [22]. 

Asymmetric transfer hydrogenation of imines catalyzed by chiral arene-Ru complexes achieves high enantioselectivity (Figure 1.34). Formic acid in aprotic dipolar solvent should be used as a hydride source. The reaction proceeds through the metal-ligand bifunctional mechanism as shown in the carbonyl reduction (Figure 1.24). 

Cationic Group 11 carbonyl complexes have been implicated in catalytic carbony-lation reactions of alkenes, arenes, alcohols, saturated hydrocarbons and aldehydes under acidic conditions [106]. While the mono- and di-carbonyls [M(CO)] and [M(C0)2] (M = Cu, Ag, Au) can be formed at atmospheric pressure of CO, only Cu(I) forms a tricarbonyl cation under such conditions [107]. Strauss and co-workers reported the observation of [Ag(CO)3] when a Fluorolube mull of Ag[Nb(OTep5)5] was subjected to 13 bar CO in an HP IR transmission cell [108]. 

Fig. 12. Polystyrene anchored arene-chromium carbonyl complex...

The carbonyl complexes listed in Table V are of two types tricarbonyl-chromium rj6-arene 77-complexes, and pentacarbonyltungsten <7-pyridine complexes, with both complex types having relatively low y. Nonlinearities increase on arene or pyridine 77-system lengthening, and on proceeding from acceptor to donor substituent on the tricarbonylchromium-coordinated arene ring. Relative magnitudes and trends thus mirror those observed with quadratic nonlinearities of these complexes (see Ref. 1)... 

The deoxygenation of arene oxides have also been achieved by using chromium carbonyl complexes. The aromatic hydrocarbons produced are partially converted to chromium complexes. Formation of 246 in methanol suggests Rh-catalyzed solvolysis, resulting in nucleophilic addition of meth-... 

A series of cobalt carbonyl complexes of polyphosphazenes have been prepared via arene coordination sites. Examples are shown as 3.65 and 3.66.112 These are synthesized via the reactions of (NPC12) with the sodium salt of the appropriate metal-arene terminated alcohol. Mixed-substituent polymers with trifluoroethoxy or phenoxy cosubstituents have also been prepared. 

Aminoalkenes, oxidative cyclization, 10, 710-711 Aminoalkoxides, on zinc compounds, 2, 371 a-Aminoalkylallenes, cycloisomerizations, 10, 720 a-Aminoalkylcuprates, preparation, 9, 519-520 -Aminoalkylidynes, diiron carbonyl complexes with cyclopentadienyl ligands, 6, 248 Aminoalkynes, hydroamination, 10, 717 a-Aminoallenes, activation by gold, 9, 574 Amino r]5-amides, in Ru and Os half-sandwich rf3-arenes,... 

Carbonyl complexes with actinides, 4, 192 (7 5-acyclic)Re(CO)3 complexes, 5, 919 allylation, 10, 663 with allylic tins, 9, 354 into 7 3-allyl palladium complexes, 8, 364 arene chromium carbonyls... 

Density functional theory studies arene chromium tricarbonyls, 5, 255 beryllium monocyclopentadienyls, 2, 75 chromium carbonyls, 5, 228 in computational chemistry, 1, 663 Cp-amido titanium complexes, 4, 464—465 diiron carbonyl complexes, 6, 222 manganese carbonyls, 5, 763 molybdenum hexacarbonyl, 5, 392 and multiconfiguration techniques, 1, 649 neutral, cationic, anionic chromium carbonyls, 5, 203-204 nickel rj2-alkene complexes, 8, 134—135 palladium NHC complexes, 8, 234 Deoxygenative coupling, carbonyls to olefins, 11, 40 (+)-4,5-Deoxyneodolabelline, via ring-closing diene metathesis, 11, 219... 

Di(arylalkynyl) ligands, in platinum(II) complexes, 8, 539 Diarylallenylidenes, in ROMP initiation, 11, 633-634 Diarylcarbinols, via zinc reagents, 9, 115—116 Diaryl-carbonyl complexes, in Ru and Os half-sandwich rf-arenes, 6, 602 Diaryl compounds... 

Manganese carbenes, preparation, 5, 825 Manganese carbonyl complexes with 776-arene complexes, 5, 787 cyclopentadienyl complexes, 5, 783 with hydrocarbon ligands, complexes, 5, 776 synthesis and characteristics, 5, 761 Manganese carbonyl halides, applications and reactivity,... 

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