Phosphorus ligand exchange equilibriums on zerovalent nickel. Dominant role for steric effects

Tolman, Chadwick A.

doi:10.1021/ja00713a007

Cited by 769 publications

(332 citation statements)

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“…To define quantitatively the steric bulk of these ligands, several authors (Alyea, Dias, Ferguson & Restivo, 1977; Richardson & Payne, 1977;Smith & Oliver, 1978) have expanded Tolman's (1970) concept of a ligand cone angle by using crystallographic coordinates to generate a series of half-cone angles (0/2) as a function of the angle of rotation about the metal-P bond, which is termed a ligand profile. A plot of the ligand profile for the dimethylphenylphosphine ligand of PTPP has been deposited.…”

Section: Trans-bis(dimethylphenylphosphine)bis(pyrazole)platinummentioning

confidence: 99%

Structure of trans-bis(dimethylphenylphosphine)bis(pyrazole)platinum, [Pt(C3H4N2)2{P(CH3)2(C6H5)}2]

Oliver¹,

Mullica²,

Grossie³

et al. 1984

Acta Crystallogr C

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plane defined by the Pt, P and coordinated N atoms of the pyrazole ligand. The coordinated pyrazole ligand is flat and virtually isometric. Selected geometrical details are Pt-P = 2.305 (3), Pt-N = 2.027 (7), average C-C (phenyl) = 1.382 (14) A, P-Pt-N = 91.7 (2) °.Introduction. The determination of the crystal structure of the title compound (hereinafter referred to as PTPP) was initiated as part of a continuing study of the steric requirements of coordinated trisubstituted phosphine ligands. Platinum metal and organoplatinum complexes are often used as catalysts for hydrogen-transfer reactions. This reaction generally includes a catalytic (2) 832 (5) 1587 (20) 3334 (7) 67 (8) C (3) 1168 (4) 2568 (25) 3979 (5) 58 (6) C (4) 3661 (4) 3216 (16) 3990 (6) 41 (7) C (5) 3509 (5) 1431 (19) 3525 (6) 53 (7) C (6) 3976 (6) 313 (19) 3267 (6) 65 (8) C (7) 4591 (6) 958 (24) 3467 (8) 83 (11) C (8) 4758 (5) 2720 (3 !) 3924 (8) 94 (13) C (9) 4294 (5) 3865 (21) 4179 (7) 74 (10) C (10) 3366 (5) 7008 (15) 4775 (6) 54 (8) C (11) 2535 (5) 5571 (17) 3366 (6) 56 (7) * Ueq defined as one third of the trace of the orthogonalized U u tensor.cycle whose intermediates are metal hydrides. These hydrides and organometallic intermediates are extremely reactive. Decomposition of this complex to the metal could easily occur under reduction situations if some stabilizing ligand were not incorporated into the metal complex. The functions of these stabilizing ligands are numerous. Primarily they bind strongly to the metal so that it may undergo any changes in oxidation state, ligation, coordination number and stereochemistry during the catalytic cycle without precipitation of the metal. These ligand s also influence the path of the reaction by their steric interactions with any incoming reactants. The most commonly used ligands for stabilizing the intermediate organometallic species are tertiary phosphines.Experimental. Crystals of the title compound obtained from Dr H. C. Clark of the University of Guelph; D m by flotation method in aqueous silver nitrate, yellow, rectangular-shaped crystal, 0.05 x 0.14 x 0.32 mm, glass-fiber mount, Enraf-Nonius CAD-4F four-circle diffractometer, graphite-monochromatized Mo Ka radiation and an Si(Li) energy-dispersive detector (MuUica, BeaU, Milligan & Oliver, 1979); cell constants from setting angles of 25 reflections; correction for Lorentz, polarization and absorption effects, t Discussion. The final atomic parameters are given in Table 1.* A perspective drawing of PTPP is shown in Fig. 1, which also illustrates the atom-labeling scheme used. A stereoscopic view of the molecular packing is shown in Fig. 2. Bond lengths and bond angles are presented in Table 2. The Pt atom lies on a crystallographic inversion r_~!!~ and has a square-planar coordination center k4,4,2/ geometry. The phenyl ring and the pyrazole rings are planar with the largest displacement of any non-H atom from its plane being 0.008 and 0.007 ./~ respectively. The planes of the phenyl ring and the pyrazole ring (1) 2.027 (7) C (2) , 1983; ...

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Section: Trans-bis(dimethylphenylphosphine)bis(pyrazole)platinummentioning

confidence: 99%

Structure of trans-bis(dimethylphenylphosphine)bis(pyrazole)platinum, [Pt(C3H4N2)2{P(CH3)2(C6H5)}2]

Oliver¹,

Mullica²,

Grossie³

et al. 1984

Acta Crystallogr C

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“…[19][20][21][22] He studied the σ-basicity and π-acidity of phosphorous ligands by looking at the stretching frequencies of the co-ordinated carbon monoxide ligands in complexes such as NiL(CO) 3 or CrL(CO) 5 , where L is the phosphorous ligand. Tolman characterized the steric bulk of a monophosphine ligand by measuring its cone angle (θ).…”

Section: D-descriptorsmentioning

confidence: 99%

In Silico Design in Homogeneous Catalysis Using Descriptor Modelling

Burello

Rothenberg

2006

IJMS

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This review summarises the state-of-the-art methodologies used for designing homogeneous catalysts and optimising reaction conditions (e.g. choosing the right solvent). We focus on computational techniques that can complement the current advances in highthroughput experimentation, covering the literature in the period 1996-2006. The review assesses the use of molecular modelling tools, from descriptor models based on semiempirical and molecular mechanics calculations, to 2D topological descriptors and graph theory methods. Different techniques are compared based on their computational and time cost, output level, problem relevance and viability. We also review the application of various data mining tools, including artificial neural networks, linear regression, and classification trees. The future of homogeneous catalysis discovery and optimisation is discussed in the light of these developments.

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“…Steric effects, however, appear to be very important. Tolinan and co-workers (34,35) have shown 011 the basis of tertiary phosphine exchange studies that steric effects are niore important than electronic efrects in determining coniplex stabilities for nickel(0) complexes of the type NiL4 (L = phosphorus donor). As a quantitative criterion of ligand size, the 'cone angle' was defined as the apex angle of the cone, centred at the metal atom, which just Can.…”

Section: Proto11 N~iclem Mrrgtzetic Reso~icr~zce Sl~ectrcimentioning

confidence: 99%

Tertiary phosphine complexes of the cobalt(III) NN′-ethylenebis(salicylideneiminato) and bisdimethylglyoximato systems

Smith¹,

Loon²,

Baird³

1976

Can. J. Chem.

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Complexes of the types [CosalenPR3]X, [Cosalen(PR3)2]X, [Co(DH)2PPh3X], and [Co(DH)2(PR3)2]ClO4, many of them new, have been prepared and characterized with respect to 1H nmr spectra, ligand field parameters, and equilibrium constants for the formation of the 2:1 salen complexes. 1H chemical shifts appear to be dominated by anisotropic rather than inductive effects, while the relative tertiary phosphine ligand field strengths appear to correlate with the steric requirements of the phosphines as well as their expected σ donor strengths. Ease of formation of the 2:1 salen complexes is determined largely by steric effects, as are trans effects in the DH systems.

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Phosphorus ligand exchange equilibriums on zerovalent nickel. Dominant role for steric effects

Cited by 769 publications

References 1 publication

Structure of trans-bis(dimethylphenylphosphine)bis(pyrazole)platinum, [Pt(C3H4N2)2{P(CH3)2(C6H5)}2]

Structure of trans-bis(dimethylphenylphosphine)bis(pyrazole)platinum, [Pt(C3H4N2)2{P(CH3)2(C6H5)}2]

In Silico Design in Homogeneous Catalysis Using Descriptor Modelling

Tertiary phosphine complexes of the cobalt(III) NN′-ethylenebis(salicylideneiminato) and bisdimethylglyoximato systems

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