Molybdenum complexes isocyanide

Seven and eight coordinate molybdenum complexes and related molybaenum(IV) oxo complexes with cyanide and isocyanide ligands. S. J. Lippard, Prog. Inorg. Chem., 1976, 21, 91-103 (44). 

Molybdenum carbonyl-isocyanide complexes may be obtained as in Section 36.2.2.1.1. In most respects isocyanides behave in a very similar way to carbon monoxide, with which they are isoelectronic. As for the carbonyls, the isocyanide complexes may be regarded as derivatives of [Mo(CNR)6] and have been reviewed comprehensively.la,b... 

Lippard, Stephen J., Seven and Eight Coordinate Molybdenum Complexes and Related Molybdenum (IV) Oxo Complexes, with Cyanide and Isocyanide... 

Cyanides.—A concise review of the seven- and eight-co-ordinate molybdenum complexes and related molybdenum(vi) 0x0 complexes, with cyanide and isocyanide ligands has appeared and Group Via cyanide complexes have been reviewed within the broader scope of transition metal cyanides. ... 

NOCgHj, Benzoyl isocyanide, chromium complex, 26 32,34,35 N0C,3H,3, Formanide, N-(l-(l-naphthal-enyl)ethyll-, rhenium complex, 29 217 NOPCjsHjj, Benzamide. 2-(diphenylphos-phino)-N-phenyl-, 27 324 NOPCjjHjj, Benzamide, Af-[2-(diphenyl-phosphino)phenyl]-, 27 323 NO2CH3, Methane, nitro-, antimony complex, 29 113 cobalt complex, 29 114 NOjCjHj, 4-Pyridinecarboxylic acid, rhodium complex, 27 292 NO2P2C3JH33, Phosphorus(l-t-), p-nitrido-bis(triphenyl-, acetate, 27 296 NO2SC3H7, L-Cysteine, molybdenum complex, 29 255,258... 

Relative susceptibility of isocyanide and carbonyl ligands to insertion depends on reaction systems. The greater thermodynamic stability of the iminoacyl complexes than the acyl complexes was demonstrated by thermal isomerization of acyl(isocyanide)molybdenum to iminoacyl(carbonyl)molybdenum complexes (Eq. 7.13) [94]. 

A more complex reaction is involved in the cooligomerization of acetylenes and tert-butyl isocyanide using nickel acetate as the catalyst (Scheme 20)43 the nature of intermediate complexes leading to the formation of 2-cyano-5-terf-butylaminopyrroles has not been established. Cocyclization of tert-butyl isocyanide with coordinated hexafluoro-2-butyne gives rise to coordinated cyclopentadienone anils for molybdenum systems,44 hence the nature of acetylene substitutents and of the organometallic catalyst play crucial roles in these processes. The pyrrole products from the former reaction can be decomposed by sulfuric acid and the overall sequence provides a simple synthesis of 5-amino-2-cyanopyrroles (Scheme 20). 

In a three-component reaction, a cationic platinum isocyanide complex [(Ph3P)2Pt(CNR)Cl][BF4] is reacted with a /3-bromoamine and butyl lithium to give an imidazoldin-2-ylidene complex.This transformation can be a two-component reaction if the isocyanide ligand contains already the necessary amine functionality. This was shown for chromium, molybdenum, tungsten, and rhenium carbonyls. 

NO, Nitrosyls, molybdenum and tungsten, 26 132, 133 NOC, Cyanate tungsten complex, 26 42 NOC4H7, 3-Butenamide nickel complex, 26 206 NOC4H , 2-Propenamide, 2-methyl-nickel complex, 26 205 NOC H, Benzoyl isocyanide chromium complex, 26 32, 34, 35 N04ReC16H, Perrhenate, tetrabutylam-monium, 26 391... 

Isocyanides are rather more reactive than CO at low-valent molybdenum centres and may react with nucleophiles, e.g. R NH2, to give carbene complexes,la e.g. equation (2), or with electrophiles to give carbyne complexes,1,4 e.g. (3). 

Simple oxidation/reduction has also been studied for a wide range of isocyanide complexes. Again those complexes containing mainly molybdenum-carbon bonds have been reviewed in... 

A number of isocyanide complexes, [Mo(CN)4(CNR)4] (R = Me, Pr, Bu allyl, NCPh2), have been made by the action of RI on Ag4[Mo(CN)8]. The crystal structure of [Mo(CN)4(CNMe)4] shows a dodecahedral geometry, with the CN- ligands at 2.177(8) A and the MeNC ligands at 2.148(8) A from the molybdenum.207 Both 13C NMR and vibrational spectroscopy indicate that only one isomer is present in solution. 

It is over eight years since the last comprehensive review appeared on metal isocyanide chemistry. In the interim, reviews have appeared on specific aspects of isocyanide chemistry. Lippard reviewed seven and eight coordination in molybdenum isocyanide compounds (7), Yamamoto reviewed metal(O)- isocyanide complexes (2), and in related reviews on car-bene complexes by Cotton and Lukehart (5), Lappert et al. (4), and Casey (5), mention was made of carbenes synthesized from metal isocyanides. 

The striking advance since 1973 has been the synthesis of homoleptic isocyanides for vanadium and almost all of the post-group-VIA metals up to group IB (see Table I), and this has been helped in some respects by synthetic rationale. For example, the discovery of the simple reductive or nonreduc-tive cleavage of multiple metal-metal bonds in suitable dinuclear complexes of molybdenum and tungsten has provided a high yield route to W(CNPh)6 and [M(CNR)7]2+ (M = Mo, W) and related complexes (5-14). During these studies the series [M(CNR)7]2+ was completed with the isola-... 

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