Isocyanides structure

The problem of the molecular geometry of the alkaline earth cyanides was solved in 1985 when Bauschlicher et al. [101] calculated that the isocyanide structures, MNC, are the most stable (Fig. 24). They found that the BeNC and MgNC molecules have barriers between the isocyanide and cyanide linkage isomers (Fig. 24) but that the heavier metals, Ca, Sr, and Ba do not. More recent calculations on MgNC [26] support this general picture for the ground X2S+ states. 

The bis(phosphinoalkyl-thioether)arene ligand with a fluorinated aryl group (l,4-(Ph2PCH2CH2S)2C6F4) was synthesized and allowed the preparation of symmetric bimetallic isocyanide structures with Rh , like 53. ... 

X-ray crystal structure, 6, 516 Benzophenanthridines synthesis from anils, 2, 416 Benzophenanthridines, tetrahydro-synthesis, 2, 469 Benzo[c]phenanthridines synthesis, 2, 414 from aryl isocyanides, 2, 411 from benzynes, 2, 432 Benzo[i]phenanthridines synthesis, 2, 414 Benzophenanthridinones... 

In solution the compounds exhibit solvent-dependent colours in dilute solution in non-polar solvents, planar monomers are present but in more concentrated solutions oligomerization occurs. In the solid state a dimeric structure has been identified (X-ray, Figure 2.30) with R = Ph there is a staggered configuration (Rh-Rh 3.193 A) but with other isocyanides (R = 4-FC6H4) the configuration is eclipsed. 

The methylisocyanide complex has a dimeric structure with a direct metal-metal bond (2.531 A) and only terminal isocyanides, in a staggered configuration (Figure 3.22). 

AuCN has a similar structure to AgCN and likewise dissolves in excess cyanide to form Au(CN)J this is important in the extraction of gold. It has been characterized as various salts (Tl, K, Bu4N, Cs) with Au-C 1.964A (Bu4N salt [91]). The thallium salt has short Au-Au (3.10A) and Au-Tl (3.50 A) interactions extended-Huckel calculations indicate the importance of relativistic effects in these covalent interactions. Isocyanides form stable complexes ... 

Rh(OEP)H reacts with CNR (R = Me, n-Bu,) to give the adduct Rh(OEP)-(H)CNR (which has no parallel in CO chemistry) which then slowly transforms to the formimidoyl insertion product, Rh(OEP)C(H)=NR. The dimer Rh(OEP))2 reacts with CNAr (Ar = 2.6-Cf,H3Mc2) in aqueous benzene to give the carbamoyl product. Rh(OEP)C(0)NHAr (characterized by an X-ray crystal structure) together with the hydride, which it.self reacts further with the isocyanide. This is suggc.sted to form via a cationic carbene intermediate, formed by attack of HiO on coordinated CNAr in concert with disproportionation to Rh(III) and Rh(l). 

The subjects of structure and bonding in metal isocyanide complexes have been discussed before 90, 156) and will not be treated extensively here. A brief discussion of this subject is presented in Section II of course, special emphasis is given to the more recent information which has appeared. Several areas of current study in the field of transition metal-isocyanide complexes have become particularly important and are discussed in this review in Section III. These include the additions of protonic compounds to coordinated isocyanides, probably the subject most actively being studied at this time insertion reactions into metal-carbon bonded species nucleophilic reactions with metal isocyanide complexes and the metal-catalyzed a-addition reactions. Concurrent with these new developments, there has been a general expansion of descriptive chemistry of isocyanide-metal complexes, and further study of the physical properties of selected species. These developments are summarized in Section IV. 

The initial work in this field appeared as a communication in 1969 8), and this work was later expanded to a full paper (9). Badley et al. described the synthesis of m-Pt(PEt3)(CNCjH5)Cl2 from Pt2(PEt3)2Cl4 and the isocyanide the bromide complex could be obtained from this complex by addition of bromide ion. These complexes were then observed to react with various substances [Eq. (16)]. A crystal structure study on the complex... 

Subsequent to the initial report by Badley et al. two communications appeared, which reported structural investigations on several products obtained from PtCl4 , methyl isocyanide, and hydrazine 33, 117) these compounds had previously been identified (incorrectly) as six-coordinate platinum(II) species 90). In addition, synthesis work in this area was extended somewhat further by these groups. The details of this work presented in these communications and in later full papers 34, 117) are summarized hy Eqs. (17). 

Aumann and Fischer (7), as part of a larger project on carbene-metal complexes, have investigated the reaction of Cr(CO)5C(OCHj)CH3 and cyclohexyl isocyanide. They describe an initial 1 1 adduct of these reagents, to which they ascribe structure (XX) it is interesting to note that neither... 

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