Isocyanide bridged dimers

Z-selective cross-coupling of terminal alkynes with isocyanides to exclusively yield (Z)-l-aza-l,3-enyne products has been achieved for the first time using a constrained geometry catalysts [Y(C5Me4Si(Me2)NR)(Alk) (THF)X] (Aik = R, dimethylaminobenzyl R = lBu, Ph, 2,4,6-Me3C6H2. The intermediate was shown to be the acetylide-bridged dimer [Y(C5Me4Si (Me2)NR)(p-C=CPh)]2.41 [24]... 

Not only does the incorporation of the dpm ligand into 1 inhibit dissociation, it also prohibits further Rh-Rh bond formation. The cations (RNC)i Rh+ can further associate to formtrimers via reaction (2). Additionally the isocyanide bridge complex 2 also self associates via reaction (3) to form a tetrarhodium species. However the dpm-bridged dimers, 1, show no evidence for self association even at the highest concentrations. Undoubtedly... 

Titanium derivatives containing carbazole (cb) ligands have been isolated and studied. Reaction of Ti(CH2SiMe3)4 with carbazole yields the alkylidene-bridged dimer [Ti(/i-CHSiMe3)(cb)2]2 (Scheme 106). A singlet at 8 14.75 is observed in the 1H NMR spectrum of the alkylidene complex. The reaction of this compound with 2,6-dimethyl-phenyl isocyanide leads to titanium derivatives containing new carbon-carbon bonds (Section 4.05.2.3).109,110... 

Reactions of [Cp Ir(NR)] R = Bu 662a or 2,6-Pr 2C6H3 662b with 2,6-xylyl isocyanide [(Xyl)NG], mesityl isocyanate, and mesityl azide were studied by Danopoulos et The bridged dimers [Cp"lt(/r-NCsFl9)]2... 

The great majority of platinum(I) complexes are binuclear with monofunctional or bifunctional bridging groups. However, there is also a series of unsupported dimers with the general structure shown in (12). These are generally stabilized by phosphine, carbonyl, and isocyanide ligands.17 Dimeric hydride complexes can have terminal or bridging hydrides and these are discussed above in Section 6.5.2.1.4. 

Dimeric and cluster compounds containing isocyanide ligands exhibit dynamic behavior in solution. The dimer Cp2Mo2(CO)5CNMe exists as a mixture of nonbridged isomers and permutamers which are rapidly inter-converted by unimolecular processes at RT. The isocyanide passes rapidly from one metal atom to the other via carbonyl or carbonyl-isocyanide doubly bridged species (205). 

The analogous uranium(III) compounds also show unusual reactivity patterns. For example, addition of COT to (Cp )3U yields a mixed metallocene dimer (18) bridged by a COT ligand in this reaction, the (Cp )3U complex has effectively acted as a formal three-electron reductant (equation 3)." A variety of substituted (Cp )3U complexes form adducts with CO and CNR (isocyanides) - these are rare examples of actinide metals with r-acidic ligands." Paramagnetic uranium alkyl complexes are active in a range of catalytic processes." ... 

Reactions of M2Cl6(SMe2) with isocyanides RNC provided products of stoichiometry M2C16(RNC)6. These contain, in fact, dimerized isocyanides as bridging ligands (251).590... 

Isocyanide complexes of the stoicheiometry HgCl2,CNR have been prepared, and are postulated to be dimeric and halide-bridged with tetrahedral mercury co-ordination they react with primary and secondary amines to yield guanidines or with AC2CH2 to yield furans through redox decomposition reactions. ... 

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