109086-52-4Relevant articles and documents
Complexes containing unbridged homonuclear or heteronuclear quadruple bonds. Crystal and molecular structures of MoWCl4(PMePh2)4, MoWCl4(PMe3)4, and Cl2(PMe3)2MoWCl2(PMePh 2)2
Luck, Rudy L.,Morris, Robert H.,Sawyer, Jeffery F.
, p. 2422 - 2429 (2008/10/08)
The reactions of Mo(η6-PhPMePh)(PMePh2)3 and Mo(η6-PhPMe2)(PMe2Ph)3 with MoCl4(THF)2 yield the homonuclear unbridged quadruply bonded complexes Mo2Cl4(PR3)4 (PR3 = PMePh2 (1), PMe2Ph (2)). Complex 1 readily undergoes phosphine substitution with PMe3 to yield Mo2Cl4(PMe3)4 (3). The reactions of Mo(η6-PhPMe2)(PMe2Ph)3 and Mo(η6-PhPMePh)(PMePh2)3 with WCl4(PPh3)2 yield the complexes MoWCl4(PR3)4 (PR3 = PMe2Ph (4), PMePh2 (5)), which are among the first to contain an unbridged quadruple bond between two different elements. Complex 5 undergoes phosphine substitution reactions with PMe3 to give sequentially Cl2(PMe3)2MoWCl2(PMePh 2)2 (6) and then MoWCl4(PMe3)4 (7). Complex 4 can also be synthesized by reacting 5 with PMe2Ph. The 31P and 1H NMR spectra, electronic and visible spectra, and cyclic voltammograms of these complexes are interpreted, and the crystal and molecular structures of 5-7 are reported. Compounds 5 and 7 were found to have disordered arrangements of the metal atoms; compound 6 with the different phosphine ligands on the metal atoms is, however, ordered with a Mo4-W bond length of 2.207 (1) A?. In 6 and 7 the molecules have crystallographic 2-fold symmetry. In all three structures the ligand arrangement over the metal-metal bond defines an eclipsed geometry with chlorine next to phosphine across the bond in a pseudo-D2d arrangement. The metal-metal distances in 5 and 7 are 2.208 (4) (average) and 2.2092 (7) A?, respectively. These values are close to distances expected on the basis of homonuclear M4-M bonds, and therefore there is no extra shortening of these bonds due to electronegativity differences. Crystal data: 5, monoclinic, space group P21/a, a = 21.511 (4) A?, b = 12.176 (6) A?, c = 40.863 (8) A?, β = 92.65(2)°, V = 10692 A?3, Dcalcd = 1.52 g cm-3 for Z = 8, R = 0.0957 for 3554 observed (I > 3σ(I)) reflections; 6, monoclinic, space group I2/a, a = 16.817 (4) A?, b = 11.925 (3) A?, c = 19.685 (5) A?, β = 103.87 (2)°, V = 3832.4 A?3, Dcalcd = 1.69 g cm-3 for Z = 4, R = 0.0364 for 2203 observed reflections; 7, monoclinic, space group I2/a, a = 17.312 (4) A?, b = 9.193 (1) A?, c = 19.085 (3) A?, β = 119.69 (2)°, V = 2638.9 A?3, Dcalcd = 1.57 g cm-3 for Z = 4, R = 0.0312 for 2084 observed reflections.
