Hydrogen bridging rhodium and tin: an NMR study of [Rh(H){(.mu.-H)SnR3}2(PPh3)2] (R = nBu, Ph)

Carlton, Laurence; Weber, Rosemarie

doi:10.1021/ic00072a001

Cited by 12 publications

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“…All hydrides reveal the typical hydride 1 H NMR signal, albeit shifted to higher frequency (5.83 ppm for 3a, 6.98 ppm for 3b, and 6.01 ppm for 3c) when compared, for example, to tributyltin hydride (4.78 ppm) [23,24]. Another parameter characteristic for monomeric triorganotin hydrides is 1 J( 119 Sn, 1 H) coupling constant, found here to be 1627 Hz for 3a, 2128 Hz for 3b to be compared to 1576 Hz for n-Bu 3 SnH and 1950 Hz for Ph 3 SnH [25]. The 119 Sn chemical shift of compound 3a (À113.2 ppm, Table 1) is strongly shifted to low frequency field when compared to its closest analog without intramolecular donor, Bu 2 PhSnH, 82 ppm [26].…”

Section: Resultsmentioning

confidence: 58%

C,N-chelated hexaorganodistannanes, and triorganotin(IV) hydrides and cyclopentadienides

Turek

Padělková

Černošek

et al. 2009

Journal of Organometallic Chemistry

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Section: Resultsmentioning

confidence: 58%

C,N-chelated hexaorganodistannanes, and triorganotin(IV) hydrides and cyclopentadienides

Turek

Padělková

Černošek

et al. 2009

Journal of Organometallic Chemistry

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“…The value of δ( 119 Sn) increases by more than 200 ppm, J (Sn−H) (further discussion of this parameter will refer to the absolute value) increases by 70%, and J (Rh−Sn) decreases by 30%. By comparison, the complexes [Rh(H){(μ−H)SnR 3 } 2 (PPh 3 ) 2 ] (R = Ph, Bu) (ref and Table ) show δ( 119 Sn) to increase (by a much smaller amount) and J (Sn−H) and J (Rh−Sn) both to decrease on exchanging Ph for Bu. In other examples of R 3 SnH complexes where substituents on tin have been varied, it has been found that as electron-donating substituents are successively replaced by electron-withdrawing substituents the magnitude of J (Sn−H) increases.…”

Section: Resultsmentioning

confidence: 99%

“…m J ( 117 Sn− 31 P) = 2608 Hz measured from the 31 P spectrum. n Solution in toluene at 295 K (data taken from ref ). At 248 K, signals other than those of 31 P are broadened.…”

Section: Resultsmentioning

confidence: 99%

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Interaction of Triphenyltin Hydride and Rhodium. Structure of [Rh(NCBPh₃)(H)(SnPh₃)(PPh₃)₂] and NMR (¹H,¹⁵N,³¹P,¹⁰³Rh,¹¹⁹Sn) Study of Pyridine-Containing Derivatives

1998

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The structure of [Rh(NCBPh(3))(H)(SnPh(3))(PPh(3))(2)] (1) (formed from [Rh(NCBPh(3))(PPh(3))(3)] and Ph(3)SnH) was determined by a single-crystal X-ray diffraction study which shows the geometry to be equally well described as a distorted tetragonal pyramid with tin at the apex or a distorted trigonal bipyramid with a hydrogen of one of the phosphine phenyl groups occupying the sixth coordination site. The tin-hydride distance of 2.31(5) Å is consistent with a weak interaction. Crystal data for 1: space group, P2(1)/c; a = 12.564(4), b = 26.942(4), c = 18.000(3) Å; beta = 92.93(2) degrees; V = 6085(2) Å(3); Z = 4; R = 0.050 for 5655 reflections with I >/= 2sigma(I). Complex 1 reacts with pyridine and substituted pyridines L (L = pyridine (py) (a), 4-(dimethylamino)pyridine (4-Me(2)Npy) (b), and 4-carbomethoxypyridine (4-MeO(2)Cpy) (c)) in dichloromethane at -25 degrees C to give trans-[Rh(NCBPh(3))(H)(SnPh(3))(PPh(3))(2)(L)] (2a-c). With L = 4-Me(2)Npy, the products cis-[Rh(NCBPh(3))(H)(SnPh(3))(PPh(3))(2)(4-Me(2)Npy)] (3) and cis- and trans-[Rh(NCBPh(3))(H)(SnPh(3))(PPh(3))(4-Me(2)Npy)(2)] (4 and 5, respectively) are also formed. At room temperature, [Rh(NCBPh(3))(H)(SnPh(3))(PPh(3))(L)] (6a-c) is the final product, decomposing over a period of hours. The pyridine-containing complexes were not isolated and were characterized by NMR spectroscopy, which showed the magnitude of the spin coupling constant J(Sn-H) to increase by factors of up to 5.5 compared with the value of 29 Hz observed for 1. At 50 degrees C, 6 (in the presence of L and PPh(3) originating from 1) undergoes reductive elimination of Ph(3)SnH to give cis-[Rh(NCBPh(3))(PPh(3))(2)(L)]; at this temperature 1 is stable, decomposing only at temperatures of 85 degrees C and above. A kinetic study of the dissociation of Ph(3)SnH from 6b (L = 4-Me(2)Npy) gave activation parameters DeltaH() = 97 +/- 6 kJ mol(-)(1) and DeltaS() = 1 +/- 20 J K(-)(1) mol(-)(1). The weakened interaction between Ph(3)SnH and rhodium is accounted for in terms of a three-center "agostic" bond.

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“…From rate constants measured at various temperatures, thermodynamic parameters can be obtained (31). The existence of a three-center bond can be inferred from values of J(E,H) (absolute magnitudes) that lie in the range Ϸ50-100 Hz (E ϭ 13 C) (13), Ϸ20-90 Hz (E ϭ 29 Si) (26,27,(32)(33)(34), and Ϸ90-350 Hz (E ϭ 119 Sn) (3)(4)(5)(6)(7)(8)(9)(10)(11) The present study examines the influence on the magnitude of J(E,H) and other NMR parameters of changes in the donor strength of a neutral ligand (pyridine) and of the number of points of attachment (the denticity) of the ligand positioned trans to tin in two series of isomeric rhodium 2 -triphenyltin hydride complexes.…”

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An NMR study oftransligand influence in rhodium η²triphenyltin hydride complexes

Carlton

Fernandes

Sitabule

2007

Proc. Natl. Acad. Sci. U.S.A.

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The complex [Rh(O2Cisoq)(H)(SnPh3)(PPh3)2] (O2Cisoq ‫؍‬ isoquinoline-1-carboxylate), characterized by x-ray crystallography, was used as a precursor to three-center bonded complexes [Rh(O2Cisoq)( 2 -HSnPh3) (PPh3)(4-Rpy)] (R ‫؍‬ carbomethoxy, acyl, bromo, aldehyde, hydrogen, methoxy, dimethylamino), which were prepared in situ from the bis(phosphine) complex in dichloromethane by addition of the pyridine. Of two isomeric forms of [Rh(O2Cisoq)( 2 -HSnPh3) (PPh3)(4-Rpy)], one, with 4-Rpy positioned trans to tin, is formed at 0°C; the other, with isoquinoline positioned trans to tin, is formed by partial (25-50%) conversion of the first isomer (in solution) upon warming to 30 -35°C for a few minutes. The relative coordination geometries of the two isomers were established by using a 15 N-enriched pyridine. NMR parameters ( 1 H, 31 P, 103 Rh, and 119 Sn) for the pyridine-containing complexes show trends consistent with a significantly greater SnH interaction in complexes having isoquinoline lying trans to tin and a threshold of donor strength for the pyridine below which the influence on Rh(SnH) bonding is minimal and above which the influence is to enhance the SnH interaction. Possible reasons for these effects are discussed. 103 Rh NMR ͉ 119 Sn NMR ͉ three-center bond ͉ trans influence T hree-center bonds between a transition metal, hydrogen, and a group 4 element [i.e., M(EH), where E carries substituents] are of interest as intermediates in numerous metal-catalyzed reactions and also in their own right as examples of how, with a suitable combination of ligands, a transition metal can bind to a bond, an interaction historically considered to be most unlikely. A transition metal complex, or three-center bonded complex, reflects a finely balanced electronic state of the metal such that a relatively small change in electron density can lead to an oxidative addition product (where permitted by the coordination geometry and oxidation state of the metal) or to the dissociation of the bond (EH) from the metal. Numerous examples of transition metal ϪR 3 CH, ϪR 3 SiH, ϪR 3 GeH (1, 2), and ϪR 3 SnH (3-11) complexes [among a wider range of types, including M(H 2 )] are known, and the relevant literature for ϪR 3 CH (12-24) complexes (almost all of which are agostic, i.e., supported) and ϪR 3 SiH (25-29) complexes has been extensively reviewed.The characterization of three-center bonds has relied heavily on x-ray diffraction, which suffers from the drawback that a hydrogen in close proximity to a heavy atom is often difficult to locate with accuracy. For the purpose of locating such hydrogens, neutron diffraction is a superior method. A further problem associated with solid samples is that packing forces within a crystal can modify or distort a three-center bond, changing it from the form in which it exists in solution. The most commonly used means of characterizing three-center bonds in solution is NMR spectroscopy, aided by the fact that 1 H, 13 C, 29 Si, 119 Sn, and in some cases the transition metal (e.g., 103 Rh), are...

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Hydrogen bridging rhodium and tin: an NMR study of [Rh(H){(.mu.-H)SnR3}2(PPh3)2] (R = nBu, Ph)

Cited by 12 publications

References 2 publications

C,N-chelated hexaorganodistannanes, and triorganotin(IV) hydrides and cyclopentadienides

C,N-chelated hexaorganodistannanes, and triorganotin(IV) hydrides and cyclopentadienides

Interaction of Triphenyltin Hydride and Rhodium. Structure of [Rh(NCBPh₃)(H)(SnPh₃)(PPh₃)₂] and NMR (¹H,¹⁵N,³¹P,¹⁰³Rh,¹¹⁹Sn) Study of Pyridine-Containing Derivatives

An NMR study oftransligand influence in rhodium η²triphenyltin hydride complexes

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Hydrogen bridging rhodium and tin: an NMR study of [Rh(H){(.mu.-H)SnR3}2(PPh3)2] (R = nBu, Ph)

Cited by 12 publications

References 2 publications

C,N-chelated hexaorganodistannanes, and triorganotin(IV) hydrides and cyclopentadienides

C,N-chelated hexaorganodistannanes, and triorganotin(IV) hydrides and cyclopentadienides

Interaction of Triphenyltin Hydride and Rhodium. Structure of [Rh(NCBPh3)(H)(SnPh3)(PPh3)2] and NMR (1H,15N,31P,103Rh,119Sn) Study of Pyridine-Containing Derivatives

An NMR study oftransligand influence in rhodium η2triphenyltin hydride complexes

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Interaction of Triphenyltin Hydride and Rhodium. Structure of [Rh(NCBPh₃)(H)(SnPh₃)(PPh₃)₂] and NMR (¹H,¹⁵N,³¹P,¹⁰³Rh,¹¹⁹Sn) Study of Pyridine-Containing Derivatives

An NMR study oftransligand influence in rhodium η²triphenyltin hydride complexes