36926-67-7Relevant academic research and scientific papers
Bond-stretch isomerism in the complexes cis-mer-MoOCl2(PR3)3: A reinvestigation
Yoon, Keum,Parkin, Gerard,Rheingold, Arnold L.
, p. 2210 - 2218 (2007/10/02)
The molecular structures of a series of complexes ds-mer-MoOCl2(PR3)3 (PR3 = PMe3, PMe2Ph) have been investigated by X-ray diffraction methods. The data indicate a large range of apparent Mo=O bond lengths. The apparent lengthening of the Mo=O bond in these complexes is rationalized in terms of compositional disorder with the isostructural trichloride derivative mer-MoCl3(PR3)3. These results suggest that, contrary to the original suggestion (Chatt, J.; Manojlovic-Muir, L.; Muir, K. W. Chem. Commun. 1971, 655-656), there is no evidence for bond-stretch or distortional isomerism for the cis-mer-MoOCl2(PR3)3 system.
Mononuclear octahedral and dinuclear edge-sharing and face-sharing bioctahedral compounds of molybdenum(III). Electronic control on the extent of metal-metal interaction in the dinuclear systems. An equilibrium, structural, and paramagnetic NMR study
Poli, Rinaldo,Mui, Humberto D.
, p. 65 - 77 (2008/10/08)
Octahedral Mo(III) mononuclear and edge-sharing and face-sharing dinuclear complexes have been investigated. The 1H NMR spectra of mononuclear compounds of formula MoX3L3 (X = Cl, Br, I; L = PMe3, PEt3, PMe2Ph) establishes their meridional configuration in solution. The temperature dependence of the spectra is consistent with Curie behavior. The face-sharing bioctahedral complexes Mo2Cl6L3 (L = PEt3, PMe2Ph) react with free phosphine to afford the corresponding edge-sharing bioctahedral complexes Mo2Cl6L4, which in turn react with more phosphine to produce the mononuclear MoCl3L3 complexes. The edge-sharing complexes slowly disproportionate to mixtures of the face-sharing dimers and monomers. The relative stability of the complexes in a phosphine-rich environment is as follows: face-sharing 2Cl6(PMe2Ph)4 compound has been crystallographically characterized. It shows the same edge-sharing bioctahedral geometry but a dramatically different metal-metal separation (2.8036 (8) ?) with respect to that of the Mo2Cl6(PEt3)4 molecule reported earlier. Possible causes for this difference are discussed. Crystal data for Mo2Cl6(PMe2Ph)4·2CHCl 3: triclinic, space group P1, a = 10.618 (3) ?, b = 13.297 (3) ?, c = 18.823 (4) ?, α = 73.96 (2)°, β = 86.16 (1)°, γ = 77.13 (2)°, V = 2490 (2) ?3, Z = 2, dc = 1.60 g·cm-3, μ(Mo Kα) = 12.88 cm-1, R = 0.034 (Rw = 0.047) for 469 parameters and 6076 unique data with Fo2 > 3σ(Fo2). The 1H NMR properties of this compound and of Mo2Cl6(PEt3)4 have been investigated at variable temperature. While the PMe2Ph complex shows only small paramagnetic shifts with a temperature-dependence consistent with a diamagnetic ground state and a slightly populated paramagnetic excited state, the PEt3 complex shows large paramagnetic shifts and a temperature dependence similar to that exhibited by the mononuclear compounds. The Mo2Cl6L3 (L = PEt3, PMe2Ph) complexes have also been structurally characterized. Crystal data for Mo2Cl6(PMe2Ph)3: triclinic, space group P1, a = 9.769 (1) ?, b = 12.9813 (6) ?, c = 13.744 (2) ?, α = 76.299 (6)°, β = 82.16 (1)°, γ = 71.682 (2)°, V = 1603.9 (5) ?3, Z = 2, dc = 1.70 g·cm-3, μ(Cu Kα) = 128.07 cm-1, R = 0.038 (Rw = 0.061) for 316 parameters and 3716 unique data with Fo2 > 3σ(Fo2). Crystal data for Mo2Cl6(PEt3)3·CH 2Cl2: monoclinic, space group P21/n, a = 14.212 (2) ?, b = 13.146 (3) ?, c = 19.090 (4) ?, β = 99.61 (1)°, V = 3516 (2) ?3, Z = 4, dc = 1.59 g·cm-3, μ(Cu Kα) = 130.51 cm-1, R = 0.080 (Rw = 0.099) for 289 parameters and 2928 unique data with Fo2 > 3σ(Fo2). Both structures show the metal-metal-bonded Mo2 core at the center of a face-sharing bioctahedral arrangement of the ligands in a relative anti configuration. The metal-metal distance is 2.753 (2) ? (PEt3) and 2.6582 (5) ? (PMe2Ph), respectively, indicating strong bonding. Both compounds exist as equilibrium mixtures of anti and gauche isomers in solution and exhibit slight paramagnetic shifts in the 1H NMR spectra with a temperature dependence similar to that of Mo2Cl6(PMe2Ph)4.
1H NMR investigation of the tetrahydrofuran replacement by phosphine ligands on MoCl3(THF)3. A trans effect
Poli, Rinaldo,Gordon, John C.
, p. 4550 - 4554 (2008/10/08)
The reactions of mer-MoCl3(THF)3 with the phosphine ligands (L) PPhxMe3-x (x = 0, 1, 2, 3), PPhxEt3-x (x = 0, 1, 2), and PR3 (R = n-Pr, n-Bu) have been investigated in CDCl3 or CD2Cl2 by paramagnetic 1H NMR spectroscopy. In all cases, a trans effect is shown by the data: the THF ligand trans to chloride is replaced much more rapidly than the two THF ligands trans to each other, to produce the observed mer-,trans-MoCl3(THF)2L intermediates. The reaction with PMe3, PEt3, PMe2Ph, PMePh2, and PEt2Ph proceeds to the tris(phosphine) mononuclear derivatives mer-MoCl3L3. For the bulkier PEtPh2 and PPh3 systems, the mer,trans-MoCl3(THF)2L intermediates completely lose THF but do not yield the corresponding tris(phosphine) derivatives; instead, they yield dinuclear products. The most nucleophilic among the above phosphines and P(n-Pr)3 and P(n-Bu)3 react with the chlorinated solvents to displace chloride anions, which generate the trans-[MoCl4(PR3)2]- anions. The latter ions have also been obtained independently from [MoCl4(THF)2]- and the appropriate phosphine.
