Bond lengths isocyanide complexes

Mo1 isocyanide complexes of the form [MoOX(CNR)4]Y (R = alkyl X=C1, Br Y = C1, Br, Brl2,13, PF6) have been prepared by several synthetic routes.125 These complexes contain a trans O—Mo—X arrangement, and in [MoOCl(CNMe)4](I3) the Mo—O, distance is 1.64(4),126 a length typical of the multiple terminal oxomolybdenum(IV) bond (Table 3). 

A mononuclear tantalum-benzyne complex (121) has been prepared by thermolysis of 120 [Eq. (20)].14 An X-ray crystal structure was reported for 121. Bond lengths for the benzyne unit are given in Table III. Complex 121 exhibits a rich insertion chemistry similar to that of Ti, Zr, and Ru benzyne complexes. Insertion reactions of 121 with ethylene, 2-butyne, acetonitrile, and carbon dioxide give 122, 123, 124, and 125, respectively (Scheme 15). Diphenylacetylene does not couple with 121, presumably because of steric constraints. Reagents with acidic protons such as methanol or terminal alkynes cleave the Ta—C bond to give butyl isocyanide and carbon monoxide, but... 

The bending at the isocyanide is electronic in origin (see below), but a linear geometry has been quoted [20] for the bulkier CNBu ligand at the same metal site. In addition, the Re-C bond length, for trans [ReCl(CNMe)(dppe)2] 2.015(17) S [19] is quite short, even slightly shorter than that exhibited by the vinylidene complex trans-[ReCl(=C=CHPh)(dppe) ], 2,046(8) S [5],... 

Apart from carbene transfer from early transition metals, insertion of isocyanides into a palladium alkyl bond, followed by alkylation, has been found to lead to palladium(ii) amino carbene complexes (Equation (21)). Isocyanide insertion first leads to an iminoacyl complex, from which the carbene is generated by alkylation or protonation of the nitrogen. The molecular structure of 55 has been determined and a Pd-G bond length of 1.97(1) A observed. 

A number of iron-platinum bimetallic clusters with isocyanide ligands have been studied those, such as 129, bridged by a dppm ligand have proved to be versatile (Scheme 30). " Both charged, 129, and uncharged, 130, complexes are possible, depending on the reaction route taken Fe-Pt bond lengths are typically 2.80 A. 

Heteronuclear dimers 131 bridged by both dppm and other ligands, such as an amino-bridged diphosphine, can be stabilized by bridging isocyanides (Scheme 31), whereupon the Fe-Pt bond length shortens to around 2.53 A. 443,i44 In these complexes, the bridging isocyanide is prone to electrophilic attack, and is converted into a bridging carbene. 

In 2009, a dipaHadium(I) amidinate compound 102 was reported with a Pd(I)-Pd(I) bond length of 2.5824(3) A (Entry 12, Table 10.7) (Figure 10.4) [67]. Complex 102 has two parallel isocyanide ligands, and can catalyze transformation of BuNC and alkynes into pyrroles. 

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