Mixed-metal cluster chemistry VII: some phosphine and alkyne chemistry of Cp2Mo2Ir2(CO)10; X-ray crystal structures of Cp2Mo2Ir2(μ-CO)3(CO)6(PMe3) and Cp2Mo2Ir2(μ4-η2-HC2Ph)(μ-CO)4(CO)4
| Autor: | Michael Lloyd Williams, Peter Conrad Healy, Nigel T. Lucas, Mark G. Humphrey |
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| Rok vydání: | 1997 |
| Předmět: |
Steric effects
chemistry.chemical_classification Chemistry Stereochemistry Organic Chemistry Cluster chemistry Alkyne Crystal structure Biochemistry Medicinal chemistry Inorganic Chemistry chemistry.chemical_compound Cyclopentadienyl complex Phenylacetylene Acetylene Materials Chemistry Physical and Theoretical Chemistry Phosphine |
| Zdroj: | Journal of Organometallic Chemistry. :519-530 |
| ISSN: | 0022-328X |
| Popis: | Reactions of Cp 2 Mo 2 Ir 2 (CO) 10 ( 1 ) with stoichiometric amounts of phosphines afforded the substitution products Cp 2 Mo 2 Ir 2 (CO) 10− x L x , (L = PPh 3 , x = 1 ( 5 ), 2 ( 6 ); L=PMe 3 , 1 ( 7 ), 2 ( 8 )), in fair to excellent yields (36–78%), shown by low temperature 31 P NMR to consist of mixtures of interconverting isomers. An X-ray structural study of Cp 2 Mo 2 Ir 2 (μ-CO) 3 (CO) 6 (PMe 3 ( 7a ), one isomer of 7 , revealed that the PMe 3 ligand occupies the electronically-preferred axial site (with respect to the plane of the bridging carbonyls). Geometries of all other isomers of 5–8 have been postulated from a combination of NMR data and results from the analogous Cp 2 Mo 2 Ir 2 (CO) 10 system. Reactions of 1 with a range of alkynes afforded Cp 2 Mo 2 Ir 2 (μ 4 -η 2 -RC 2 R′)(CO) 8 (R = R′ = Ph ( 9 ), H ( 14 ); R = H, R′ - Ph ( 10 ), 4-C 6 H 4 NO 2 ( 11 ), 4,4′-C 6 H 4 C≡CC 6 H 4 NO 2 ( 12 ), CH 2 Br ( 13 )) in fair to good yields (34–80%). An X-ray structural study of 10 revealed that the alkynes have formally inserted into the Mo−Mo bond of 1 , to afford clusters with a pseudooctahedral core geometry. Qualitative analysis of reaction rates for the syntheses of 9–14 revealed the trends acetylene > terminal alkyne > internal alkyne and 4-nitrophenylacetylene > phenylacetylene, assigned to a combination of electronic and steric effects. |
| Databáze: | OpenAIRE |
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