Formyl transition-metal complexes

III. Physical Properties of Transition Metal Formyl Complexes. 13... 

Possible routes (i) hydrolysis of thioformyl or similar derivative (ii) dealkylation of M=CHOR carbenes Scheme 1. Some synthetic approaches to transition metal formyl complexes. 

All anionic transition metal formyl complexes described in the literature through the end of 1980 (21-47) are compiled in Table I. Since several of these have been prepared with more than one counterion, cations are not specified in the table. Geometric isomers are not assigned unless warranted by direct spectroscopic evidence. Also, the stability data in Table 1 should be regarded as qualitative, since decomposition rates have been shown to be dependent on both purity and counterion. When half-lives are specified, they are usually based upon measured rate constants. 

All neutral transition metal formyl complexes described in the literature through the end of 1980 (52-68) are compiled in Table II. General comments made in the previous section regarding Table 1 apply. 

PHYSICAL PROPERTIES OF TRANSITION METAL FORMYL COMPLEXES... 

Transition metal formyl complexes are capable of donating hydride to several classes of substrates, of which ketones and aldehydes are pro-... 

It is evident that transition metal formyl complexes possess a unique and rich chemistry. There are numerous surprising contrasts to reactions of transition metal acyl complexes. Since synthetic routes to formyl com-... 

Flowing afterglow techniques are yet another approach to studying ion-molecule reactions of organometallic species (, 52). Here ion-molecule reactions are conducted in a flow of inert buffer gas (usually He), so that all reagents and products are completely thermalyzed. Representative experiments have employed bracket-ing/competition experiments (cf., Equations 45-47) to obtain information such as hydride affinities of metal carbonyls and transition metal formyl complex stabilities (, ). ... 

Reactions between [Cp Ir(PMe3)(Me)(OTf)] and aldehydes (RCHO) proceed with high selectivity to give the hydrocarbyl carbonyl salts [Cp Ir(PMe3)(R)(CO)]OTf (137, R = Me, Et, Pr, Ph, 1-ethylpropyl,/>-Tol, Mes, (Z)-l-phenyl-l-propen-2-yl, vinyl, Bu, 1-adamantyl). The tandem C-H bond activation/decarbonylation reaction afforded the first isolated tertiary alkyl complexes of Ir. X-ray diffraction studies were carried out on Mes, Bu, and 1-adamantyl derivatives. Hydride reduction of the /)-Tol complex provided an example of a rare transition metal formyl complex, [Cp lr(PMe3)(p-Tol)(CHO)]. ... 

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