Metallosite Selectivity Studies in Reactions of Tetrahedral MCo₃ Carbonyl Clusters (M = Fe, Ru) with Cyclohexylphosphine. Skeletal Rearrangements Leading to Tri- and Pentanuclear Phosphinidene Clusters and Crystal Structures of RuCo₄(μ₄-PCy)(μ-CO)₂(CO)₁₁ and RuCo₂(μ₃-PCy)(CO)₉

Abstract

We have studied the metallosite selectivity of substitution reactions at heterometallic tetranuclear clusters of the type HMCo3(CO)12 (M = Fe, Ru). Monosubstitution with PCyH2 occurs with a different metalloselectivity as a function of M. When M = Fe, substitution of a Co-bound CO ligand occurs whereas when M = Ru, the phosphine ligand is bound to Ru. Introduction of a second substituent (PCyH2 or NMe3) occurs in both cases at cobalt and, in the case of HFeCo3(CO)11(PCyH2), at a cobalt that does not carry the PCyH2 substituent. The clusters HMCo3(CO)11(PCyH2) (2a, M = Fe; 2b, M = Ru) transform in solution to give the corresponding μ3-phosphinidene-capped heterotrinuclear clusters MCo2(μ3-PCy)(CO)9 (4a, M = Fe; 4b, M = Ru). The μ4-phosphinidene-capped intermediate RuCo4(μ4-PCy)(μ-CO)2(CO)11 (5b) could be fully characterized, whereas the analogous species could not be isolated when M = Fe. The transformation of 2a,b was accelerated by addition of Me3NO. This work demonstrates that a reaction which represents a partial cluster fragmentation, with a nuclearity change from 4 to 3, may occur via the intermediacy of a larger cluster, of nuclearity 5. Reactions and products were studied by IR and 1H, 31P{1H}, and 59Co NMR spectroscopic methods, and the clusters 4b and 5b have been characterized by X-ray diffraction.

Grafting and Thermal Stripping of Organo‐Bimetallic Clusters on Au Surfaces: Toward Controlled Co/Ru Aggregates

“…[39][40][41] Substitution of one cobalt-bound carbonyl group by the phosphine ligand occurs in the trans position with respect to the ruthenium cap, in agreement with previously established www.chemeurj.org reactivity patterns. [39,[42][43][44] The axial orientation of the functional phosphine ligand is comparable to the situation in [RuCo 3 (H)(CO) 11 A C H T U N G T R E N N U N G (PPh 3 )]. [40] The Co À P length of 2.236(2) is similar to the values of 2.223(8) and 2.228(2) found in [RuCo 3 (CO) 11 [41] respectively, but slightly shorter than the value of 2.261(5) found in [RuCo 3 (CO) 11 …”

Alkyl, Silyl, and Phosphane Ligands—Classical Ligands in Nonclassical Bonding Modes

“…The interconversion between the [Co‐P,Ru‐P] and [Co‐P,Co‐P] isomers 21 and 22 , which involves phosphane migration between Ru and Co has also been discussed [Eq. (8) ] 58…”

Reactivity of the Heterometallic Clusters [HMCo3(CO)12] and [Et4N][MCo3(CO)12] (M = Fe, Ru) toward Phosphine Selenides, Including Selenium Transfer. Crystal Structures of [HRuCo3(CO)7(μ-CO)3(μ-dppy)], [MCo2(μ3-Se)(CO)7(μ-dppy)], and [RuCo2(μ3-Se)(CO)7(μ-dppm)] [dppy = Ph2(2-C5H4N)P, dppm = Ph2PCH2PPh<

“…The reactivity of tetrahedral clusters of the type [HMCo 3 (CO) 12 ] (M = Ru and Fe) with nucleophiles (especially tertiary phosphines, phosphites, amines) generally leads to a metallosite-selective substitution of one or more carbonyl ligands (on the basal plane). − The first substitution by donor ligands generally occurs by replacement of a terminal axial carbonyl of a cobalt atom. A recent exception was observed in the reaction of [HMCo 3 (CO) 12 ] with PCyH 2 which led to CO substitution at the apical Ru center . On the contrary, the introduction of a second ligand can take place either on a basal or on the apical metal. − ,− , The effects of phosphine substitution on the other ligands are usually restricted to minor distortions, for example, asymmetry in the carbonyl coordination; rarely is the position of the hydride ligand also affected. −,− …”

“…A recent exception was observed in the reaction of [HMCo 3 (CO) 12 ] with PCyH 2 which led to CO substitution at the apical Ru center. 19 On the contrary, the introduction of a second ligand can take place either on a basal or on the apical metal. [10][11][12][15][16][17][18]20 The effects of phosphine substitution on the other ligands are usually restricted to minor distortions, for example, asymmetry in the carbonyl coordination; rarely is the position of the hydride ligand also affected.…”