Labile organometallic complex

Most other work with d8 complexes concerns 5-coordinate organometallic complexes. Some examples are given in Table 14.73 74,76"80 The electronic spectrum of Fe(CO)s has been measured and the lowest absorption has been identified as LF dxy, dx2 y2 -> dz2 according to the one-electron level scheme in Scheme 11.81 Such a transition should yield labilization principally along the z-axis due to the... 

Table 6 is composed of dissociative reactions for quite different classes of compounds. These data indicate several features, which appear to be general, (i) Organometallic complexes with a d configuration are relatively labile, (ii) Complexes with a configuration are relatively inert, (hi) Dissociative reactivity apparently follows the order d o > d > d > d for a homologous series. 

More coimnonly, it is to be expected that the reactivity of a mixed-metal cluster will be comparable to that of the most labile metal. For example, the rates of CO dissociation from (/u,-H)Ru3 Os (/u.-COMe)(CO)io fall in the series as Rus (4500) > RU2OS (1100) > RuOs2(220) OS3 (1). If this is the case, the relative rates for a series can provide information concerning the number of metal atoms which participate in such a transformation (see also Mechanisms of Reaction of Organometallic Complexes and Ligand Substitution). 

The lability of water molecules in the q5-organometallic complexes Cp Ir(H20)3 + and Cp Rh(H20)3+ and the mechanism of water exchange with bulk solvent water molecules were discussed in the previous section.159 A subsequent study in which the kinetics of substitution of a water molecule in these species by several ligands (L) at... 

Labile H2 complexes [Re(jj -H2)(PR3)2L3] (L = CO, CN-f-Bu) formed upon protonation of ReH(PR3)2L3 are stabilized by large noncoordinating anions [BAr4] in comparison to [Bp4]. Similar W complexes have been widely investigated see Tungsten Organometallic Chemistry. ... 

The synthetic methods which have been used include modern versions of established methods of metal colloid preparation such as the mild chemical reduction of solutions of transition metal salts and complexes and newer methods such as radiolysis and photochemical reduction, metal atom extrusion from labile organometallics. And the use of metal vapor synthesis techniques. Some of these reactions have been in use for many years, and some are the results of research stimulated by the current resurgence in metal colloid chemistry. The list of preparative methods is being extended daily, and, as examples of these methods are described below, the reader will quickly be made aware that almost any organometallic reaction or physical process which results in the deposition of a metal is in fact a resource for the metal colloid chemist. The acquisition of new methods requires only the opportunism of the synthetic chemist in turning a previously negative result into a synthetic possibility. 

The configurational stability of the metal center in organometallic complexes in solution therefore depends on the nature of the ligands coordinated to the metal center and the spatial configurations of their substituents [16,106,111,119]. Early work on the Ru(II) arene iodido complexes [Ru(r -/ -cymene)(LL )I] (LL = (Sc)-(-)-dimethyl(l-phenylethyl)amine) revealed that they were more configurationally labile (ti/2 = 15.2 min at 269 K in CD2CI2) compared with their chlorido analogs [120] with a half-life T1/2 = 107.8 min under the same... 

The effect of the cis ligand(s) on substitution rates has been noted especially in the chemistry of octahedral organometallic complexes. In general, Ae effect is less than the trans effect. The order of cis labilization for various ligands is... 

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