RESUMEN
The σ-arsolido complex [Mo(AsC4Me4)(CO)3(η5-C5H5)] is alkylated at arsenic by MeOTf to afford the pentamethylarsole complex [Mo(MeAsC4Me4)(CO)3(η5-C5H5)](OTf) while iodomethane affords a mixture of [Me2AsC4Me4]I, [MoMe(CO)3(η5-C5H5)], [MoI(CO)3(η5-C5H5)] and the arsole complexes cisoid- and transoid-[MoI(MeAsC4Me4)(CO)2(η5-C5H5)] and transoid-[Mo{C(îO)Me}(MeAsC4Me4)(CO)2(η5-C5H5)], The arsole ligand in [Mo(MeAsC4Me4)(CO)3(η5-C5H5)](OTf) is readily liberated by NaI in acetone to afford free MeAsC4Me4 and [MoI(CO)3(η5-C5H5)]. In a similar manner, the reaction of [Mo(AsC4Ph4)(CO)3(η5-C5H5)] with MeI affords MeAsC4Ph4 and [MoI(CO)3(η5-C5H5)], while [Mo{AsC4(SiMe3)-2-Me2-3,4}(CO)3(η5-C5H5)] with MeOTf affords [Mo{MeAsC4(SiMe3)-2-Me2-3,4}(CO)3(η5-C5H5)](OTf). The reaction of [Mo(AsC4Me4)(CO)3(η5-C5H5)] with activated alkynes (RCîCR: R = CF3, CO2Me) does not proceed via [4 + 2] cyclo-addition but rather electrophilic attack at arsenic followed by metallacyclisation with incorporation of a carbonyl ligand in the spirocyclic complexes [Mo{As(C4Me4)CRîCRCO}(CO)2(η5-C5H5)].
RESUMEN
The σ-stannyl complexes [M(SnnBu3)(CO)n(η5-C5H5)] (n = 3, M = Mo, W; n = 2, M = Fe) serve as mild reagents for the installation of σ-arsolyl ligands in transmetallation reactions with As-chloro-arsoles ClAsC4R4 (R = Me, Ph) to afford [M(σ-AsC4R4)(CO)n(η5-C5H5)]. The reaction of [Cr(SnnBu3)(CO)3(η5-C5H5)] with ClAsC4Ph4 most likely proceeds in a similar manner but is immediately followed by rapid formation of (AsC4Ph4)2 and [Cr2(CO)6(η5-C5H5)2]. The reaction of [Mo(SnnBu3)(CO)3(η5-C5H5)] with ClAsC4(SiMe3)-2,5-Me2-3,4 is accompanied by monodesilylation to afford [Mo{σ-AsC4(SiMe3)-2-Me2-3,4}(CO)3(η5-C5H5)]. The slow reaction of [Fe(SnnBu3)(CO)2(η5-C5H5)] with ClAsC4Me4 produced only traces of [Fe(σ-AsC4Me4)(CO)2(η5-C5H5)] due to competition with the Diels-Alder type dimerisation of the haloarsole. Although attempts to decarbonylate the σ-arsolyl complexes were unsuccessful, computational analysis suggests that the trigonal 'XL' arsolenium coordination mode is viable.
RESUMEN
The reactions of [W(îCBr)(CO)2(Tp*)] (Tp* = tris(dimethylpyrazolyl)borate) with LiTeCîCR (R = SiMe3, SiiPr3, iPr, nBu, tBu, Ph, C6H4Me-4, methylimidazol-2-yl) afford the first alkynyltellurolatocarbynes [W(îCTeCîCR)(CO)2(Tp*)]. Both the WîC and CîC multiple bonds are prone to metal addition as exemplified by treatment with [MCl(SMe2)] (M = Cu, Au) to afford the hexametallic complex [W2Cu4(µ-CTeCîCSiiPr3)2Cl4(CO)4(Tp*)2] and [WAu(µ-CTeCîCSiMe3)Cl(CO)2-(Tp*)] which evolves to the unusual hypervalent [WAu(µ-CTeCl4)(SMe2)(CO)2(Tp*)].
RESUMEN
The new bis(alkynyl)mercurial Hg{CîCSeCîW(CO)2(Tp*)}2 (Tp* = tris(dimethylpyrazolyl)borate) forms adducts with fluoride and phenathroline, the structures of which are interpreted in the context of two-coordinate mercury presenting a σ-torroid for spodium bonding.
RESUMEN
Treatment of the rhodium pincer complexes [RhCl(RPm)] (RPm = N,N'-bis(di-R-phosphinomethyl)perimidinylidene, R = Ph, Cy) with triphenylcyclopropenium hexafluorophosphate affords rhodacyclobutadiene complexes. These in turn react with activated alkynes (RCîCCO2Me, R = H, CO2Me) to afford unusually stable cyclopropenylvinyls, implicating the intermediacy of σ-cyclopropenyl isomers. In contrast, treatment of [RhCl{py(NHPtBu2)2-2,6}] with the same reagent instead results in double functionalisation (SEAr) at the pincer backbone.