The Photochemistry of (Diene)(hydro)[tris(3,5-dimethylpyrazolyl)borato]rhodium Complexes, Preliminary Communication

Ferrari, Arlen; Merlin, Mattia; Sostero, Silvana; Rüegger, Heinz; Venanzi, L. M.

doi:10.1002/(sici)1522-2675(19990908)82:9<1454::aid-hlca1454>3.0.co;2-3

Cited by 9 publications

(1 citation statement)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Heating of a methanol solution of 2b at 80 °C for 2 d led to ∼40% conversion of 2b to 3 . A very small amount of Tp′Rh(CO)H 2 (doublet at δ −12.925, 1 J Rh–H = 18 Hz) was observed in the 1 H NMR spectrum. A small doublet of doublets seen at δ −15.158 ( 1 J Rh–H = 18.5 Hz, 2 J P–H = 26 Hz) in the 1 H NMR spectrum may arise from the product of formaldehyde C–H addition to the rhodium complex.…”

Section: Resultsmentioning

confidence: 99%

Determination of Rhodium–Alkoxide Bond Strengths in Tp′Rh(PMe₃)(OR)H

et al. 2016

View full text Add to dashboard Cite

The active fragment [Tp'Rh(PMe3)], generated from a thermal precursor Tp'Rh(PMe3)(CH3)H, underwent oxidative addition of water and alcohols to give O-H adducts of the type Tp'Rh(PMe3)(OR)H (R = H, Me, Et, (n)Pr, (n)Bu, CH2Ph, (i)Pr, c-pentyl, CH2CF3, CH2CH2OH) at ambient temperature. These activation products eliminate water or alcohols in benzene, which allows determination of the relative metal-oxygen bond energies by using previously established kinetics techniques. Analysis of the relationship between the relative M-O bond strengths and O-H bond strengths showed a linear correlation with RM-O/O-H of 0.97 (3) for aliphatic alcohols. The two extraordinary substrates (R = CH2CF3, CH2CH2OH) both have stronger M-O bonds than would be predicted from this trend, suggesting the stabilization of the M-O bond when an electron-withdrawing substituent is present as previously seen in M-C bond strengths. In addition, the O-H activation products of aliphatic alcohols are thermally unstable at 80 °C, as rearrangement to form Tp'Rh(PMe3)H2 from β-elimination is observed after 1 or 2 d. Benzyl alcohol and 2,2,2-trifluoroethanol activation products were stable. For benzyl alcohol, although the O-H activation product was kinetically favored, the C-H activation products of the benzene ring were thermodynamically preferred.

show abstract

Section: Resultsmentioning

confidence: 99%

Determination of Rhodium–Alkoxide Bond Strengths in Tp′Rh(PMe₃)(OR)H

et al. 2016

View full text Add to dashboard Cite

show abstract

¹⁰³Rh NMR spectroscopy and its application to rhodium chemistry

Ernsting

Gaemers

Elsevier

2004

Magnetic Reson in Chemistry

View full text Add to dashboard Cite

Rhodium is used for a number of large processes that rely on homogeneous rhodium-catalyzed reactions, for instance rhodium-catalyzed hydroformylation of alkenes, carbonylation of methanol to acetic acid and hydrodesulfurization of thiophene derivatives (in crude oil). Many laboratory applications in organometallic chemistry and catalysis involve organorhodium chemistry and a wealth of rhodium coordination compounds is known. For these and other areas, 103Rh NMR spectroscopy appears to be a very useful analytical tool. In this review, most of the literature concerning 103Rh NMR spectroscopy published from 1989 up to and including 2003 has been covered. After an introduction to several experimental methods for the detection of the insensitive 103Rh nucleus, a discussion of factors affecting the transition metal chemical shift is given. Computational aspects and calculations of chemical shifts are also briefly addressed. Next, the application of 103Rh NMR in coordination and organometallic chemistry is elaborated in more detail by highlighting recent developments in measurement and interpretation of 103Rh NMR data, in relation to rhodium-assisted reactions and homogeneous catalysis. The dependence of the 103Rh chemical shift on the ligands at rhodium in the first coordination sphere, on the complex geometry, oxidation state, temperature, solvent and concentration is treated. Several classes of compounds and special cases such as chiral rhodium compounds are reviewed. Finally, a section on scalar coupling to rhodium is provided.

show abstract