Benzenechromium tricarbonyl

Bailey, M. F. Dahl, L. F. (1965) "Three-dimensional crystal structure of benzenechromium tricarbonyl with further comments on the dibenzenechromium structure, Inorg. Chem. 4, 1314-1319. 

These compounds provide interesting subjects for study, since there arises the possibility of two quite different types of product molecule, in addition to the target compound the carbonyl and the pure diarene. These possibilities are well illustrated in the study by Baumgartner and Zahn of benzenechromium tricarbonyl, as is shown in Table 11. 

Table 11. Retention and yields of Cr from benzenechromium tricarbonyl (Baumgartner and Zahn )...

The first such compound to be studied was benzenechromium tricarbonyl (14), which gave the results shown in Table VI. The striking thing about... 

Benzenechromium tricarbonyl 371 is deprotonated by BuLi in EtiO-THF at —40 °C in a reaction that needs carefnl control for good yields . The prodnct 372 can be sily-lated to give 373 in 60% yield (Scheme 158). Toluenechrominm tricarbonyl lithiates non-regioselectively on the ring (bnt at the benzylic position with Na or K bases). Excess base can lead to polylithiation . 

Among the compounds that form complexes with silver and other metals are benzene47 (represented as in 6) and cyclooctatetraene. When the metal involved has a coordination number greater than 1, more than one donor molecule participates. In many cases, this extra electron density comes from CO groups, which in these complexes are called carbonyl groups. Thus, benzenechromium tricarbonyl (7) is a stable compound.4 Three arrows are... 

In a related compound, benzenechromium tricarbonyl, C6H6Cr(CO)3377, internal rotation was seen to be nearly unhindered. 

These, to some extent, are related to redistribution reactions but, of course, do not lie within the scope of this review. Probably one of the first redistribution reactions of ir-bonded compounds is the exchange of carbonyl groups with 7r-bonded benzene (85) on chromium leading to the mixed compound, benzenechromium tricarbonyl. 

It is well known that certain transition metal organometallic complexes, such as ferrocene, cymantrene (cyclopentadienylmanganese tricarbonyl) and butadieneiron tricarbonyl, and to a lesser extent, benzenechromium tricarbonyl, form organic derivatives and have an extensive derivative chemistry of their own. The parent complexes have already been discussed there follows a summary of the main features observed in the mass spectra of their organic derivatives (Table II, at the end of this section). 

Selective 1,4-hydrogenation of 1,3-dienes to (Z)-alkenes is possible with benzenechromium tricarbonyl as a catalyst precursor. Only those conjugated dienes that can adopt a cisoid conformation, and hence chelate to the metal, are hydrogenated. Methyl sorbate (68) is reduced to methyl (Z)-3-hexenoate (70) [46,47]. The reaction... 

Benzenechromium tricarbonyl (Fluorobenzene)chromium tricarbonyl Cyclopentadienyl)rhenium tricarbonyl (1,3-Cyclohexadiene)iron tricarbonyl (1,3-Cyclohexadienyl)manganese tricarbonyl (T rimethylenemethane)iron tricarbonyl (Cyclopentadienyl)manganese tricarbonyl (1,3-Butadiene)iron tricarbonyl... 

Figure 1. Molecular structure of benzenechromium tricarbonyl complex with thiourea as determined by x-ray analysis. There are three thiourea molecules per organometallic unit.

Figure 2. View of molecular packing arrangement in benzenechromium tricarbonyl-(thiourea)3 complex. The view is down the crystal c-axis, looking down the honeycomb formed by the thiourea lattice.

Addition of earbanions to ir-arenechromium tricarbonyl complexes. Experimental details for addition of earbanions to n -benzenechromium tricarbonyl and for subsequent transformations (oxidation, reaction with electrophiles) of the resulting addition compounds have been published. ... 

Ph2Hg, benzenechromium tricarbonyl, and diphenylbis(chromium tricarbonyl) were identified in the products of photolysis of the title complex by chromatographic analysis 47). No further details were given. 

In one of the earlier studies, Strohmeier and Mittnacht found 98) that the exchange of benzenechromium tricarbonyl with labeled benzene is essentially slower than the corresponding reaction with (7r-C7Hg)Cr(CO)3. Kinetics of the isotopic exchange reaction... 

Cyclobutadiene iron tricarbonyl is permercurated easily , but benzenechromium tricarbonyl is less reactive than free benzene ... 

PHENYLATION n-Benzenechromium tricarbonyl. rr-(Chlorobenzene)chtomium tri-carhonyl. 

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