39049-79-1

Upstream product

• 13463-40-6 iron pentacarbonyl 
• 638-21-1 phenylphosphane 
• 86372-87-4 Fe₃(P(C₆H₅))2(CO)8(NCCH₂CH₃) 

Relevant academic research and scientific papers

Proton reduction by phosphinidene-capped triiron clusters

Bis(phosphinidene)-capped triiron carbonyl clusters, including electron rich derivatives formed by substitution with chelating diphosphines, have been prepared and examined as proton reduction catalysts. Treatment of the known cluster [Fe3(CO)9(μ3-PPh)2] (1) with various diphosphines in refluxing THF (for 5, refluxing toluene) afforded the new clusters [Fe3(CO)7(μ3-PPh)2(κ2-dppb)] (2), [Fe3(CO)7(μ3-PPh)2(κ2-dppv)] (3), [Fe3(CO)7(μ3-PPh)2(κ2-dppe)] (4) and [Fe3(CO)7(μ3-PPh)2(μ-κ2-dppf)] (5) in moderate yields, together with small amounts of the corresponding [Fe3(CO)8(μ3-PPh)2(κ1-Ph2PxPPh2)] cluster (x = -C4H6-, -C2H2-, -C2H4-, -C3H6-, -C5H4FeC5H4-). The molecular structures of complexes 3 and 5 have been established by X-ray crystallography. Complexes 1–5 have been examined as proton reduction catalysts in the presence of p-toluenesulfonic acid (p-TsOH) in CH2Cl2. Cluster 1 exhibits two one-electron quasi-reversible reduction waves at –1.39 V (ΔE = 195 mV) and at –1.66 V (ΔE = 168 mV; potentials vs. Fc+/Fc). Upon addition of p-TsOH the unsubstituted cluster 1 shows a first catalytic wave at –1.57 V and two further proton reduction processes at –1.75 and –2.29 V, each with a good current response. The diphosphine-substituted derivatives of 1 are reduced at more negative potentials than the parent cluster 1. Clusters 2–4 each exhibit an oxidation at ca. +0.1 V and a reduction at ca. –1.6 V; for 4 conversion to a redox active successor species is seen upon both oxidation and reduction. Clusters 2–4 show catalytic waves in the presence of p-TsOH, with cluster 4 exhibiting the highest relative catalytic current (icat/i0 ≈ 57) in the presence of acid, albeit at a new third reduction process not observed for 2 and 3. Addition of the dppf ligand to the parent diphosphinidene cluster 1 gave cluster 5 which exhibited a single reduction process at –1.95 V and three oxidation processes, all at positive values as compared to 2–4. Cluster 5 showed only weak catalytic activity for proton reduction with p-TsOH. The bonding in 4 was investigated by DFT calculations, and the nature of the radical anion and dianion is discussed with respect to the electrochemical data.

Metal cluster nitrile derivatives

Thermal and photochemical activation of Fe3(μ3-PC6H5) 2(CO)9 and Co4(μ4-PC6H5) 2(CO)10, in acetonitrile or propionitrile solutions, provided the reactive nitrile clusters: Fe3(μ3-PC6H5) 2(CO)8(NCR), Fe3(μ3-PC6H5) 2(CO)7(NCR)2, and Co4(μ4-PC6H5) 2(CO)9(NCR). Using these nitrile derivatives, a series of substitution derivatives with PF3, P(OR)3, PR3, and AsR3 ligands were prepared in high yield. Interestingly, the bis(acetonitrile) derivative of the iron cluster had both nitrile groups on the same (basal) iron atom. X-ray crystallographic studies for single crystals of Fe3(μ3-PC6H5) 2(CO)7(NCCH3)2 established that they utilize the centrosymmetric orthorhombic space group Pnma - C2h16 with a = 13.103 (2) A?, 6 = 16.972 (2) A?, c = 25.038 (5) A?, and Z = 8. The asymmetric unit contains two crystallographically independent molecules both of which possess rigorous Cs-m symmetry. The molecular structure of Fe3(μ3-PC6H5) 2(CO)7(NCCH3)2 is related to that of the parent Fe3(μ3-PC6H5) 2(CO)9 with two of the equatorial carbonyl ligands on a single basal Fe atom replaced by acetonitrile ligands. Basically, the stereochemistry of the phosphorus- and arsenic-based ligand derivatives of the iron cluster were analogous to that of the parent nitrile derivatives from which they were obtained. Conformationally, there were differences that can be rationalized in terms of steric and electronic factors and of fluxional features of the molecules. Studies of the temperature-dependent 13C spectra of the parent ion cluster and its derivatives established certain dominant mechanistic pathways for ligand site exchange in the cluster.