Rhodium-103 NMR

Carlton, Laurence

doi:10.1016/s0066-4103(07)63003-8

Cited by 29 publications

(31 citation statements)

References 438 publications

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“…[36] This gives rise to chemical shift values in the range −9000 to −8000 ppm that can be converted and compared to the values ranging from −700 to +300 ppm relative to ( 103 Rh) = 3.16 MHz by using the formula reported by Carlton. [37] Crystal data of [Rh(COD)((S,S)-DIOP)]PF 6 …”

Section: Determination Of 103 Rh Chemical Shiftmentioning

confidence: 99%

Probing the stereo‐electronic properties of cationic rhodium complexes bearing chiral diphosphine ligands by ¹⁰³Rh NMR

Fabrello

Dinoi

Perrin

et al. 2010

Magnetic Reson in Chemistry

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(103)Rh NMR represents a powerful tool to assess the global electronic and steric contribution of diphosphine ligands on [Rh(COD)(diphosphine)](+) complexes. In the case of DIOP, BINAP and MeDUPHOS, this approach proved to be more informative than classical CO-stretching frequency measurements. After validation, this method has been extended to a set of seven diphosphines. (103)Rh NMR measurements on [Rh(COD)(diphosphine)]PF(6) lead to the following order of donor properties: dppe > MeBPE > MeDUPHOS > dppb > DIOP > BINAP > Tol-BINAP. This trend has been validated by DFT in the case of DIOP, BINAP and MeDUPHOS. In conjunction, (31)P NMR chemical shift has been shown to reflect the ring constraints of the Rh-diphosphine scaffold. This contribution is a step towards a mechanistic investigation of the catalytic hydrogenation of unsaturated substrates by (103)Rh NMR and DFT.

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Section: Determination Of 103 Rh Chemical Shiftmentioning

confidence: 99%

Probing the stereo‐electronic properties of cationic rhodium complexes bearing chiral diphosphine ligands by ¹⁰³Rh NMR

Fabrello

Dinoi

Perrin

et al. 2010

Magnetic Reson in Chemistry

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“…[32,44] Differences between the 183 W chemical shifts of the phosphine and phosphite complexes can be rationalized in terms of the weak/strong dimension, where P(OR) 3 provides a stronger ligand field than PR 3 , leading to larger E and lower δ. The trend to higher δ in the phosphine complexes occurs as the substituents on phosphorus become progressively less electron donating, i.e.…”

Section: X-ray Crystallographymentioning

confidence: 99%

“…At the risk of further obscuring matters, a new chemical shift reference for organotungsten NMR of ( 183 W) = 4.15 MHz is proposed in the hope that it might enjoy the success of the comparable standard used in rhodium NMR. [31,32] …”

Section: Introductionmentioning

confidence: 99%

A tungsten-183 NMR study of cis and trans isomers of [W(CO)4(PPh3)(PR3)](PR3 = phosphine, phosphite)

et al. 2008

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Tungsten-183 NMR data are reported for the complexes cis- and trans-[W(CO)4(PPh3)(PR3)] (PR3 = PnBu3, PMe3, PMe2Ph, PMePh2, PPh3, P(4-C6H4OMe)3, P(4-C6H4Me)3, P(4-C6H4F)3, P(OMe)3, P(OEt)3, P(OPh)3 and for PCy3, P(NMe2)3(trans isomer only). The 183W chemical shift (obtained by indirect detection using 31P) is found to be related to the PR3 ligand parameters nu and theta (Tolman electronic factor and cone angle, respectively) for the cis isomers and to nu (but only poorly to theta) for the trans isomers. The 183W-31P spin coupling constant is also related, less clearly for P-C than for P-N and P-O bonded ligands, to nu. Chemical shifts are referenced to an absolute frequency Xi (183W) = 4.15 MHz, which is proposed as a calibration standard for 183W NMR. The structures of cis-[W(CO)4(PPh3)(PMe3)] and cis-[W(CO)4(PPh3){P(4-C6H4F)3}] are reported.

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“…Such an effect (substituent R bonded to ligands other than pyridine) has been observed for complexes [Rh(η 5 ‐C 5 H 4 R)(CO) 2 ] and [W(CO) 4 (PPh 3 )(PR 3 )] and can be rationalized as follows. The two major influences on a transition metal chemical shift are (from a simplified form of the Ramsey equation) ΔE −1 , where ΔE is the energy difference between the highest occupied and lowest unoccupied molecular orbitals, and < r −3 >, where r is the average radius of a d orbital . The ability of a ligand to increase the d orbital radius, r , is related to its polarizability (hard/soft property).…”

Section: Resultsmentioning

confidence: 99%

“…The two major influences on a transition metal chemical shift are (from a simplified form of the Ramsey equation [29] ) ΔE À1 , where ΔE is the energy difference between the highest occupied and lowest unoccupied molecular orbitals, and <r À3 >, where r is the average radius of a d orbital. [30] The ability of a ligand to increase the d orbital radius, r, is related to its polarizability (hard/soft property). For ligands that create a low ΔE, such as pyridine, which is a good s donor and poor p acceptor, polarizability effects will largely determine the value of the metal chemical shift.…”

Section: Resultsmentioning

confidence: 99%

Tungsten‐183 NMR study of cis‐[W(CO)₄(PPh₃)(4‐RC₅H₄N)]; effect of varying the σ donor strength of the pyridine

Carlton

Mokoena

Fernandes

2013

Magnetic Reson in Chemistry

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Tungsten-183 NMR data are reported for the complexes cis-[W(CO)4(PPh3)(4-RC5H4N)] (R = H, Me, Ph, COMe, COPh, OMe, NMe2, Cl, NO2). The (183)W chemical shift (obtained by indirect detection using (31)P) is found to correlate with the Hammett σ function for the group R, with (183)W shielding increasing approximately linearly with the donor strength of the pyridine over a range of 93 ppm. The X-ray structures of cis-[W(CO)4(PPh3)(4-MeOC5H4N)] and cis-[W(CO)4(PPh3)(4-PhCOC5H4N)] are also reported.

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Rhodium-103 NMR

Cited by 29 publications

References 438 publications

Probing the stereo‐electronic properties of cationic rhodium complexes bearing chiral diphosphine ligands by ¹⁰³Rh NMR

Probing the stereo‐electronic properties of cationic rhodium complexes bearing chiral diphosphine ligands by ¹⁰³Rh NMR

A tungsten-183 NMR study of cis and trans isomers of [W(CO)4(PPh3)(PR3)](PR3 = phosphine, phosphite)

Tungsten‐183 NMR study of cis‐[W(CO)₄(PPh₃)(4‐RC₅H₄N)]; effect of varying the σ donor strength of the pyridine

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Rhodium-103 NMR

Cited by 29 publications

References 438 publications

Probing the stereo‐electronic properties of cationic rhodium complexes bearing chiral diphosphine ligands by 103Rh NMR

Probing the stereo‐electronic properties of cationic rhodium complexes bearing chiral diphosphine ligands by 103Rh NMR

A tungsten-183 NMR study of cis and trans isomers of [W(CO)4(PPh3)(PR3)](PR3 = phosphine, phosphite)

Tungsten‐183 NMR study of cis‐[W(CO)4(PPh3)(4‐RC5H4N)]; effect of varying the σ donor strength of the pyridine

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Probing the stereo‐electronic properties of cationic rhodium complexes bearing chiral diphosphine ligands by ¹⁰³Rh NMR

Probing the stereo‐electronic properties of cationic rhodium complexes bearing chiral diphosphine ligands by ¹⁰³Rh NMR

Tungsten‐183 NMR study of cis‐[W(CO)₄(PPh₃)(4‐RC₅H₄N)]; effect of varying the σ donor strength of the pyridine