Nitrosyl complexes insertion reactions

A parallel situation appears to obtain for the mixed allyl nitrosyl complex Ru(NO)(C3H5)L2 prepared by Schoonover and Eisenberg (231). This complex which is coordinatively saturated (NO+ and rf -allyl), forms a CO adduct which is assigned a bent nitrosyl structure (231). Further reaction under CO leads to the formation of Ru(CO)3L2 with the possible elimination of acrolein oxime. The coupling of the allyl and nitrosyl ligands can be viewed in this case as nucleophilic attack of NO- on an f/3-allyl species. Unlike in reaction (110), both of the moieties to be coupled lie within the same coordination sphere. The significance of these results is that it lends viability to the notion embodied in (109) in which a migratory insertion of nitrosyl occurs as NO-. 

Neutral and cationic homoleptic (see Homoleptic Compound) tnngsten-isocyanide complexes W(CNR)6 and [W(CNR)y] + (R = alkyl, aryl) are known, and W(CO)e (CNR) (n=l-3) complexes may be prepared from W(CO)6 and excess isocyanide in the presence of catalytic amounts of C0CI2 or PdO. Iso-cyanides are isoelecfronic with CO and also insert into the W-R bonds of alkyl complexes (see Alkyl Complexes). For instance, the alkyl-nitrosyl complexes Cp W(NO)(X)(CH2Bfr) (X = NHBfr, OBfr) react with CNBu to afford -iminoacyl complexes, and the isocyanide complexes, Cp W(CO)2(Me)(CNR) (10, R = alkyl), rearrange to afford either -iminoacyl Cp W(CO)2( -MeCNR)(ll) or ij -l-azaallyl Cp W(CO)2( -CH2CHNR) (12) derivatives, depending upon the reaction conditions (equation 4). ... 

Still more problematic is the apparent migratory insertion of nitric oxide into transition metal-carbon bonds, an important reaction in metal nitrosyl complexes and one that may be relevant to biochemical reactions (7). On the evidence of isotopic labeling and kinetic experiments, the insertion of NO into the C0-CH3 bond of the (cyclopentadie-nyl)cobalt complex (i75-C5H5)Co(NO)(CH3), which occurs in Reaction (3),... 

Reactions conducted with the more basic phosphine, PEtj, occur differently and afford the bent nitrosyl complex at the bottom left of Scheme 9.6. The reactions of this bent nitrosyl complex are inhibited by added phosphine, and ties inhibition suggests tiiat tiie bent NO is unreactive toward insertion. The linear nitrosyl in the starting complex appears to be more reactive. Some data suggest that the insertion of NO is slower than the insertion of CO. For example, MeFe(NO)(CO)3 reacts with CO to form the acyl complex [MeC(0)]Fe(N0)(C0)3. ... 

Two reviews by F. Basolo make interesting reading. Both are retrospective, and center mainly on work carried out by the author and his co-workers. One deals with conventional ligand substitutions.the other with substitution reactions of carbonyl and nitrosyl complexes/ and both contain material on four- and five-coordinate compounds. A review by R. Romeo on dissociative reaction pathways in platinum(II) chemistry takes the form of a useful compilation of the various reaction types which might lead to three-coordinate 14-electron species. These include -eliminations and various insertion reactions as well as ligand replacements and isomerizations. ... 

Codeposition of silver vapor with perfluoroalkyl iodides at -196 °C provides an alternative route to nonsolvated primary perfluoroalkylsilvers [272] Phosphine complexes of trifluaromethylsilver are formed from the reaction of trimethyl-phosphme, silver acetate, and bis(trifluoromethyl)cadmium glyme [755] The per-fluoroalkylsilver compounds react with halogens [270], carbon dioxide [274], allyl halides [270, 274], mineral acids and water [275], and nitrosyl chloride [276] to give the expected products Oxidation with dioxygen gives ketones [270] or acyl halides [270] Sulfur reacts via insertion of sulfur into the carbon-silver bond [270] (equation 188)... 

Chromatography cyclophosphazenes, 21 46, 59 technetium, 11 48-49 Chromites, as spinel structures, 2 30 Chromium, see Tetranuclear d-block metal complexes, chromium acetylene complexes of, 4 104 alkoxides, 26 276-283 bimetallics, 26 328 dimeric cyclopentdienyl, 26 282-283 divalent complexes, 26 282 nitrosyls, 26 280-281 trivalent complexes, 26 276-280 adamantoxides, 26 320 di(/ >rt-butyl)methoxides, 26 321-325 electronic spectra, 26 277-279 isocyanate insertion, 26 280 substitution reactions, 26 278-279 [9]aneS, complexes, 35 11 atom... 

The symmetry of transformation (107) is identical to that of the alkyl car-bonyl-to-acyl conversion, (5), and therefore the difference in the propensities of these insertions to occur must relate to differences in the orbital energetics of the two processes. Since the metal-nitrosyl jr-interaction is a dominant feature of the electronic structure in NO+ complexes, and since it will be weakened by the formation of a nitroso species, one can expect (107) to be correspondingly less favorable than acyl formation in (5). If reaction (107) does occur, however, one can readily envisage tautomerism of the nitroso ligand to an oxime. The reactive nature of the oxime may then create difficulties in the identification and isolation of organonitrogen products, and indeed, this may have obscured general observation of transformation (107) in the past. 

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