537683-52-6Relevant articles and documents
Reactivity of the unsaturated dimolybdenum anion [Mo2(η5-C5H5)2(μ-PCy2)(μ-CO)2]- towards electrophiles based on p- and d-block elements
Alvarez, M. Angeles,García, M. Esther,Ramos, Alberto,Ruiz, Miguel A.
, p. 36 - 44 (2010/09/04)
The 30-electron binuclear anion [Mo2Cp2(μ-PCy2)(μ-CO)2]- reacts with the chlorophosphite ClP(OEt)2 or the organotin chlorides Cl2SnPh2 or ClSnPh3 to give compounds of the formula trans-[Mo2Cp2(μ-E)(μ-PCy2)(CO)2], (E = P(OEt)2, SnPh3, SnPh2Cl). In contrast, this anion reacts with the organosilicon chlorides ClSiR3 (R = Ph, Me) to give unstable silyloxycarbyne-bridged complexes [Mo2Cp2(μ-PCy2)(μ-COSiR3)(μ-CO)], which rapidly hydrolyze to give the known hydride [Mo2Cp2(μ-H)(μ-PCy2)(CO)2]. Two main types of products were also observed in the reactions of the title anion with different chlorocomplexes of the transition and post-transition metals. Thus, the reactions with [MCl2Cp2] (M = Ti, Zr) give moisture-sensitive isocarbonyl-bridged complexes of the type [Mo2Cp2(μ-COMClCp2)(μ-PCy2)(μ-CO)]. In contrast, softer metallic electrophiles such as [AuCl(PR3)] (R = iPr, ptol) react with the anion at the dimolybdenum site to form new trimetallic clusters of the formula [AuMo2Cp2(μ-PCy2)(CO)2(PR3)], also retaining a Mo-Mo triple bond. Subsequent reactions of the latter products with the solvate complexes [Au(PR3)(THF)][PF6] give the tetranuclear clusters [Au2Mo2Cp2(μ-PCy2)(CO)2(PR3)2][PF6] (Mo-Mo = 2.5674(3) A? and Au-Au = 2.7832(2) A? when R = iPr). Finally, the reaction of the title anion with HgI2 gives the pentanuclear cluster [Hg{Mo2Cp2(μ-PCy2)(CO)2}2] or the trinuclear cluster [Mo2Cp2(μ-HgI)(μ-PCy2)(CO)2] depending on the stoichiometry being actually used for the reaction. The trinuclear species is only stable in tetrahydrofuran (THF), and decomposes to give a mixture of the dimeric species [Mo2Cp2(μ-HgI)(μ-PCy2)(CO)2]2 along with variable amounts of the known iodide-bridged complex [Mo2Cp2(μ-I)(μ-PCy2)(CO)2].
Structure and bonding in the unsaturated hydride- And hydrocarbyl-bridged complexes [Mo2(η5-C5H5) 2(μ-X)(μ-PCy2)(CO)2] (X = H, CH 3, CH2Ph, Ph). Evidence for the presence of α-agostic and π-bonding interactions
Garcia, M. Esther,Ramos, Alberto,Ruiz, Miguel A.,Lanfranchi, Maurizio,Marchio, Luciano
, p. 6197 - 6212 (2008/10/09)
The reactions of the triply bonded anion [Mo2Cp 2(μ-PCy2)(μ-CO)2]- (Li + salt) with [NH4]PF6, MeI, and PhCH 2Cl give, with good yields, the corresponding hydride- or alkyl-bridged derivatives [Mo2Cp2-(μ-X)(μ-PCy 2)(CO)2] (X = H, Me, CH2Ph). The related phenyl complex [Mo2Cp2(μ-Ph)(μ-PCy2-CO) 2] can be obtained upon reaction of the above anion with Ph 3PbCl. According to the corresponding X-ray diffraction studies, the latter complex displays its phenyl group bonded to the dimetal center exclusively through the ipso carbon atom, while the methyl and benzyl complexes adopt an asymmetric α-agostic structure whereby one of the C-H bonds of the bridgehead carbon is bound to one of the molybdenum atoms. The intermetallic distances remain quite short in all cases, 2.56-2.58 A. In solution, the hydride complex exhibits dynamic behavior involving mutual exchange of the carbonyl ligands. The alkyl derivatives behave similarly to each other in solution and also exhibit dynamic behavior, possibly implying the presence of small amounts of a nonagostic structure in equilibrium with the dominant α-agostic structure. Density functional theory calculations (B3LYP, B3PW91) correctly reproduce the experimental structures, and predict an α-agostic structure for both the methyl and benzyl complexes. The bonding in the above hydride and hydrocarbyl complexes was analyzed using molecular orbital, atoms in molecules, and natural bond orbital methodologies. The intermetallic binding in the hydride complex can be thus described as composed of a tricentric (Mo2H) plus two bicentric (Mo2) interactions, the latter being of σ and π types. In the hydrocarbyl-bridged complexes, analogous tricentric (Mo2C), and bicentric (Mo2) interactions can be identified, but there are additional interactions reducing the strength of the intermetallic binding, these being the α-agostic bonding in the case of the alkyl complexes and a π-donor interaction from the π-bonding orbitals of the hydrocarbon ring into suitable metal acceptor orbitais, in the case of the phenyl complex. The strength of these additional interactions have been estimated by second-order perturbation analysis to be of 70.3 (Me), 89.2 (CH2Ph), and 52.2 (Ph) kJ mol-1, respectively.
