TERTIARY PHOSPHINE COMPLEXES OF CHROMIUM(III) - SYNTHESES, MAGNETIC-PROPERTIES, AND SINGLE-CRYSTAL STRUCTURE STUDIES ON CR2CL6(PME3)4, CR2CL6(PET3)4, AND CR2CL6(DMPM)2

Anhydrous chromium(III) chloride reacts, in appropriate solvents at reflux temperatures, with each of the monodentate tertiary phosphines PMe3 and PEt3 and with the bidentate tertiary phosphine bis(dimethylphosphino)methane (dmpm) to form Cr2Cl6-(PMe3)4 (1), Cr2Cl6(PEt3)4 (2) and Cr2Cl6(dmpm)2 (3), respectively. Complex 1 was also obtained from the reaction of Cr2(OAc)4, Me3SiCl, and PMe3. The magnetic susceptibility of 2 varies with temperature in the range 5-300 K, in agreement with the Curie-Weiss law, and this indicates no significant interaction between the Cr atoms. However, the magnetic properties of 3 suggest that there may be an antiferromagnetic interaction between the Cr atoms at low temperatures (1.3–10 K). The Cr•••Cr distances are as follows: 1, 3.587 (5) Å; 2, 3.637 (2) Å; 3, 3.480 (1) Å. Crystal data: Cr2Cl6(PMe3)4 (1), orthorhombic, space group Pmen, a = 13.452 (3) Å, b = 18.292 (3) Å, c = 11.317 (2) Å, V = 2784.7 (9) Å3, Z = 4, R = 0.064 (Rw = 0.092) for 877 data with Fo2 > 3s(Fo2); Cr2Cl6(PEt3)4 (2), orthorhombic, space group Pnma, a = 20.184 (3) Å, b = 19.066 (2) Å, c = 10.642 (1) Å, V = 4095.3 (9) Å, Z = 4, R = 0.0498 (Rw = 0.072) for 1889 data with F2 = 3s(Fo2); Cr2Cl6(dmpm)2 (3), monoclinic, space group P21/a, a = 8.505 (2) Å, b = 20.574 (2) Å, c = 8, 481 (1) Å, μ = 92.66°, V = 1482.4 (3) Å, Z = 2, R = 0.0332 (Rw = 0.0423) for 2099 data with Fo2 > 3s(Fo2). © 1990, American Chemical Society. All rights reserved.