110511-63-2Relevant academic research and scientific papers
Chemical transformations on phosphido-bridged clusters. Synthesis of the 48- and 50-electron acetylide complexes Ru3(CO)n{μ3-η 2-C≡C(i-Pr)}(μ-PPh2) (n = 8, 9) and their reactions with diazomethane. Carbon-carbon bond forming reactions and the conversion of acetylide to allenyl clusters
Nucciarone,MacLaughlin,Taylor,Carty
, p. 106 - 117 (2008/10/08)
The 50-electron phosphido-bridged clusters Ru3(CO)9{μ3-η 2-C≡CR}(μ-PPh2) (R = i-Pr, 2a; R = t-Bu, 2b) have been synthesized from Ru3(CO)11(Ph2PC≡CR) (1a,b) via controlled oxidative insertion into the P-C bond of the phosphinoalkyne. These compounds lose CO at 60°C affording the 48-electron clusters Ru3(CO)6(μ-CO)2{μ3-η 2-C≡CR}(μ-PPh2) (R = i-Pr, 3a; R = t-Bu, 3b). Full single-crystal X-ray structural analyses of 2a and 3b have been carried out. Compound 2a crystallizes in the monoclinic space group P21/c with a = 13.189 (1) A?, b = 9.674 (1) A?, c = 22.481 (2) A?, β = 91.82 (1)°, and Z = 4. The structure was refined to R and Rw values of 0.025 and 0.028 with use of 2743 observed (3785 measured) reflections. The molecule has an open triangular structure with two strong Ru-Ru interactions and an axial μ-PPh2 group bridging the long (Ru(1)-Ru(3) = 3.4658 (6) A?) edge. The 48-electron decarbonylation product 3b crystallizes in a triclinic cell, space group P1, with a = 9.674 (1) A?, b = 13.373 (1) A?, c = 13.654 (1) A?, α = 108.97 (1)°, β = 72.64 (1)°, γ = 93.79 (2)°, and Z = 2. Final R and Rw values based on 4911 observed diffractometer data were 0.029 and 0.031. Principal structural features are an equatorial phosphido bridge across a short Ru-Ru bond (Ru(1)-Ru(3) = 2.8257 (4) A?), two bridging carbonyls across the other edges of the Ru3 triangle, and a μ3-η2-acetylide on the Ru3 face. Reactions of 2a and 3a with CH2N2 have been explored. The cluster 3a reacts rapidly with diazomethane affording the μ3-allenyl cluster Ru3(CO)8{μ3-η3-CH 2=C=C(i-Pr)}(μ-PPh2) (4) via coupling of a methylene (CH2) unit with the acetylide. Isolation of 4 and further reaction with CH2N2 gave the μ-methylene cluster Ru3(CO)7(μ-CH2){μ3-η 3-CH2=C=C(i-Pr)}(μ-PPh2) (5). Both 4 and 5 have been fully characterized by single-crystal X-ray diffractometry. Complex 4 crystallizes in space group P21/c with a = 11.892 (2) A?, b = 12.200 (2) A?, c = 19.698 (4) A?, β = 93.22 (1)°, and Z = 4. Crystals of 5 are monoclinic space group P21/c with a = 11.890 (2) A?, b = 11.973 (1) A?, c = 19.675 (2) A?, β = 90.10 (1)°, and Z = 4. Final R and Rw values were 0.029 and 0.031, respectively, for 4 and 0.035 and 0.039, respectively, for 5. The clusters 4 and 5 are remarkably similar in skeletal stereochemistry with the allenyl fragments and the phosphido bridges being almost identically coordinated on the trinuclear framework. In 5 however a μ-CH2 group bridges one Ru-Ru bond, replacing a CO ligand in 4. The nature of the carbon-carbon bond forming reactions and the structural relationships between 2a, 3b, 4, and 5 are discussed.
