92479-08-8Relevant academic research and scientific papers
Oxidative addition to M-M quadruple bonds. Preparation of new edge-sharing bioctahedral complexes of the type (L-L)Cl2M(μ-Cl)2MCl2(L-L) (M = Mo, W, L-L = 1,2-bis(diphenylphosphino)ethane; M = Mo, L-L = 1-(diethylphosphino)-2-(diphenylphosphino)ethane)
Agaskar,Cotton,Dunbar,Falvello,O'Connor
, p. 4051 - 4057 (2008/10/08)
The reaction of chlorine with the quadruply bonded compounds M2Cl4(dppe)2 (dppe = Ph2PCH2CH2PPh2) affords the oxidized products M2(μ-Cl)2Cl4(dppe)2 (M = Mo, W). A third compound Mo2(μ-Cl)2Cl4(dedppe)2 (dedppe = Et2PCH2CH2PPh2) was isolated from the reaction of Mo2Cl4(dedppe)2 with dichloromethane. The air-stable M26+ complexes were characterized by elemental analysis, IR spectroscopy, and X-ray crystallography. Crystals of Mo2Cl6(dppe)2·4CH2Cl 2 (1) are monoclinic, space group C2/m, with a = 17.288 (2) A?, b = 18.500 (2) A?, c = 13.855 (4) A?, β = 121.14 (2)°, V = 3793 (3) A?3, and Z = 2. The structure was refined to R = 0.0694 (Rw = 0.0718), and quality of fit = 2.21. The molecule has crystallographic 2/m (C2h) symmetry; the virtual symmetry of the core is D2h. The Mo-Mo distance is 2.762 (1) A?. Mo2Cl6(dedppe)2·2CH2Cl 2 (2) crystallizes in the monoclinic system, space group P21/c with the following unit cell dimensions: a = 12.148 (6) A?, b = 10.707 (5) A?, c = 22.529 (5) A?, β = 101.57 (4)°, V = 2870 (4) A?3, Z = 2. The binuclear Mo2 unit resides on a crystallographic inversion center. Final residuals for the structure are R = 0.064 (Rw = 0.079); goodness of fit = 1.56. The Mo-Mo distance is 2.785 (3) A?, which is very similar to the distance in 1. The ditungsten complex W2Cl6(dppe)2·4CH2Cl 2 (3) crystallizes in the triclinic system, space group P1, with a = 12.521 (2) A?, b = 13.956 (3) A?, c = 20.690 (5) A?, α = 104.36 (4)°, β = 92.34 (3)°, γ = 112.34 (4)°, V = 3202 (4) A?3 and Z = 2. The asymmetric unit is defined by two independent molecules of W2Cl6(dppe)2, each of which resides on an inversion center, and four molecules of CH2Cl2 that occupy general positions. The two ditungsten molecules are structurally alike, and their corresponding bond distances and angles are very similar. The average W-W distance is 2.681 [1] A?. Successful refinement gave R = 0.0441 (Rw = 0.0538). In all three cases, the molecules possess an edge-sharing bioctahedral geometry in which the metals are bridged by two Cl atoms. Two bidentate phosphine ligands assume a chelating mode in the equatorial plane, which is defined by the metal and μ-Cl atoms; above and below the equatorial plane are apical positions occupied by terminal chloride ligands. Compounds 1 and 3 have been characterized magnetically, and 1 has been further studied by cyclic voltammetry and UV-visible spectroscopy.
