Displacement of the Benzene Solvent Molecule from Cr(CO)5(benzene) by Piperidine: A Laser Flash Photolysis Experiment

Bengali, Ashfaq A.; Charlton, Samantha B.

doi:10.1021/ed077p1348

Cited by 10 publications

(16 citation statements)

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“…The inclusion of excess ethylene, methyl acrylate (CH 2 ϭCHCO 2 CH 3 ; MA) or dimethyl fumarate (trans-CH 3 CO 2 CHϭCHCO 2 CH 3 ; DMFU) in the illuminated reaction vessel produces Ru(CO) 4 …”

Section: Experimental Backgroundmentioning

confidence: 99%

“…In the undergraduate laboratory, these compounds are most often prepared by thermal reaction of the parent binary metal carbonyl with a suitable ligand, L (1). When thermal routes fail, photochemical synthesis is a viable alternative for carbonyl ligand replacement (2), but, with a few notable exceptions (3)(4)(5)(6)(7), this approach can often be too technically demanding for the conventional undergraduate laboratory. Even in these instances, the use of sophisticated equipment can be required (4,5), potentially limiting the applicability of the experiment to only the most well-equipped institutions.…”

mentioning

confidence: 99%

“…When thermal routes fail, photochemical synthesis is a viable alternative for carbonyl ligand replacement (2), but, with a few notable exceptions (3)(4)(5)(6)(7), this approach can often be too technically demanding for the conventional undergraduate laboratory. Even in these instances, the use of sophisticated equipment can be required (4,5), potentially limiting the applicability of the experiment to only the most well-equipped institutions. Furthermore, the inherent challenges of carrying out synthetic photochemistry on metal carbonyl compounds have thus far limited undergraduate laboratory investigation to the group six metals (Cr, Mo, W) (3)(4)(5)(6)(7).…”

mentioning

confidence: 99%

“…Ruthenium pentacarbonyl is thermally unstable and is difficult to handle (8), which often renders thermal reactions inconvenient for the synthesis of Ru(CO) 4 L compounds. However, advantage can be taken of the efficient photochemical metal-metal bond cleavage in Ru 3 (CO) 12 to prepare Ru(CO) 4 (η 2 -alkene) compounds; when a sufficiently labile alkene is used, the latter can serve as [Ru(CO) 4 ] transfer reagents to generate different Ru(CO) 4 L compounds (9,10).…”

mentioning

confidence: 99%

“…However, advantage can be taken of the efficient photochemical metal-metal bond cleavage in Ru 3 (CO) 12 to prepare Ru(CO) 4 (η 2 -alkene) compounds; when a sufficiently labile alkene is used, the latter can serve as [Ru(CO) 4 ] transfer reagents to generate different Ru(CO) 4 L compounds (9,10). In contrast, thermal reactions of Ru 3 (CO) 12 typically yield ligand-substituted trinuclear clusters (11).…”

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confidence: 99%

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Photochemical Synthesis and Ligand Exchange Reactions of Ru(CO)4(n2-alkene) Compounds

2007

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Substituted mononuclear metal carbonyls play a central role in the discussion of organometallic chemistry. In the undergraduate laboratory, these compounds are most often prepared by thermal reaction of the parent binary metal carbonyl with a suitable ligand, L (1). When thermal routes fail, photochemical synthesis is a viable alternative for carbonyl ligand replacement (2), but, with a few notable exceptions (3-7), this approach can often be too technically demanding for the conventional undergraduate laboratory. Even in these instances, the use of sophisticated equipment can be required (4, 5), potentially limiting the applicability of the experiment to only the most well-equipped institutions. Furthermore, the inherent challenges of carrying out synthetic photochemistry on metal carbonyl compounds have thus far limited undergraduate laboratory investigation to the group six metals (Cr, Mo, W) (3-7).Ruthenium pentacarbonyl is thermally unstable and is difficult to handle (8), which often renders thermal reactions inconvenient for the synthesis of Ru(CO) 4 L compounds. However, advantage can be taken of the efficient photochemical metal-metal bond cleavage in Ru 3 (CO) 12 to prepare Ru(CO) 4 (η 2 -alkene) compounds; when a sufficiently labile alkene is used, the latter can serve as [Ru(CO) 4 ] transfer reagents to generate different Ru(CO) 4 L compounds (9, 10). In contrast, thermal reactions of Ru 3 (CO) 12 typically yield ligand-substituted trinuclear clusters (11).From a pedagogic perspective, the students are introduced to the notion that it is not always a metal-carbonyl bond that cleaves in photochemical reactions, but that larger metal clusters can be induced to fragment with useful results. Although Ru 3 (CO) 12 is relatively expensive, 1 the experiments that will be described can be carried out on a scale of only a few mg͞student, with the compounds characterized in situ by IR spectroscopy rather than being isolated. This exposes the students to a common microscale method used in research laboratories when working with reagents that are either very costly or are difficult to prepare in large quantities. We have found that our students appreciate being exposed to the (somewhat novel) prospect of carrying out a photochemical synthesis and being able to learn a great deal about the chemistry of a system without necessarily needing to submit an isolated compound at the conclusion of the experiment. Experimental BackgroundThe photochemical fragmentation of Ru 3 (CO) 12 can take place under a variety of conditions, ranging from filtered high-intensity light (9, 10) to sunlight or conventional fluorescent lighting (12), rendering the experiment quite flexible in terms of the sophistication of equipment required. The UV-vis spectrum of Ru 3 (CO) 12 reveals a single band at the short wavelength extreme of the visible spectrum, centered at 390 nm ( Figure 1). This band has been assigned to a σ → σ* transition in the Ru 3 framework (13), and allows one to understand why a metal-metal bond is cleaved upon photochem...

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Section: Experimental Backgroundmentioning

confidence: 99%