Cyclopentadienyl complex isocyanide

Insertions of isocyanide into niobium-carbon bonds follow a path similar to that with vanadium, resulting in the formation of the 7]2-iminoacyl complexes, which can then be involved in further chemistry.175 176 The reaction of acetone with cyclopentadienyl complex 110 under a carbon monoxide atmosphere gives the if -acetone compound 111. Complex 111 subsequently undergoes either stepwise insertion of two isocyanides via 112 or double insertion of the isocyanide to give complex 113 (Scheme 48).177... 

Cyclization takes place when tert-butylisocyanide, benzaldehyde, anilinium chloride, and carbonyl(dicyano)cyclopentadienyl ferrate are reacted, the carbene complex 42 being the result (95JOM(491)135). /50-butyraldehyde, tert-butyl isocyanide, ammonium hexafluorophosphate, and [(T -Cp)Fe(CO)(CN)2] give the cationic bis-carbene 43. 

The chemistry of rhenium(I) is dominated by organometallic compounds which are not covered by this review. Thus, cyclopentadienyl and related compounds, where the organometallic part of the molecule dominate the properties will generally not be considered. Nevertheless, compounds with carbonyl or isocyanide co-ligands will be treated when they can be regarded as constituents of a typical coordination compound or the compounds are of fundamental interest in a radiopharmaceutical context such as the hexakis(isocyanide)rhenium(I) cations. For the same reason a separate section has been included which gives a brief summary of recent attempts to develop synthetic routes to tiicarbonylrhenium(I) complexes for nuclear medical applications. 

C-H bond dissociation energies, 1, 298 C-N triple bond additions, 10, 427 C02, ketene, ketenimine complexes, 5, 84 CO and CNR reductive coupling, 5, 66 cyclopentadienyl alkyl and aryls, 5, 66 cyclopentadienyl carbonyl complexes, 5, 64 cyclopentadienyl hydrides, 5, 69 cyclopentadienyl isocyanide complexes, 5, 65 rf-acyl and rj2-iminoacyl complexes, 5, 82 fj3-complexes, 5, 87... 

In a recent study of the IR and NMR spectra of the cyclopentadienyl-copper and indenylcopper complexes with fcrf-butyl isocyanide, Saegusa and co-workers favored a rr-bonded structure for the former, but were uncertain of the latter 246). As the indenylcopper complex was deutera-ted at only positions 1 and 3 a preference was expressed for a o-bonded structure with 1,3-copper shifts. The structure of indenylcopper will doubtless be the subject of further research. 

Examples in organocopper chemistry are the synthesis of h -cyclopentadienyl-copper complexes with phosphite, phosphine or isocyanide ligands via the reaction of h -CjHjTl with Cu(I) halide-ligand complexes in pentane or THE at 25°C . 

A wide variety of organometallic, carbonyl, and isocyanide metal-metal bonded dimeric complexes of this oxidation state had been studied before 1985. The overall chemical shift range is the broadest for this particular oxidation state, spanning from the most shielded tricarbonyl species (-2100p.p.m.) to the most deshielded quadruply bonded Mo(II)-Mo(Il) dimer (-1-4150 p.p.m.). Typically, the monomeric and dimeric species resonate at opposite ends of the chemical shift scale. Because many complexes had been observed by 1985, Table 16, which contains only one carbonyl and two cyclopentadienyl species, serves to supplement the large number of Mo(II) complexes discussed previously by Minelli et al. ... 

Table6 IR data of different cyclopentadienyl U(III) isocyanide complexes [74]...

In this article the term organometallic compound includes alkyl and aryl derivatives of the rare earths—the transition metals of group III, scandium, yttrium, lanthanum and the lanthanides cerium to liitetium with covalent metal-to-carbon a-bonds, as well as the so-called 77-complexes with more than monohapto metal-to-carbon bonds, for example cyclopentadienyl and olefin complexes, metal acetylides, but not carbonyls, cyanides and isocyanide complexes. Derivatives of scandium, yttrium and lanthanum are included and discussed together with the compounds of the lanthanides, because of many similarities in the synthesis and the chemistry of these organometallic derivatives of the rare earths. 

Cyclopentadienyl and allyl complexes also undergo reduction by means of an excess amount of isocyanide ... 

Isocyanide complexes have found numerous applications in organic synthesis and catalysis. Isocyanides undergo polymerization in the presence of many transition metal complexes, for instance, metal carbonyls, metallocenes, cyclopentadienyl carbonyls, nickel(II), palladium(II), and cobalt(II) complexes. Exceptionally high activity is exhibited by nickel and cobalt carbonyls. The resulting polymers are Schiff bases ... 

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