| Popis: |
Anhydrous Chromium(III) chloride has been treated with the tertiary phosphines Me3P, Et3P, Bun3P, PhPEt2, and Ph2PEt by heating under reflux in benzene or toluene at 60°. Only in the first three cases did reaction take place and only for Et3P and Bun3P could the green complexes [CrCl3(PR3)2]2 be isolated. These complexes lose one mole of trialkylphosphine on gentle warming in 1:1 CCl4–CH2Cl2 to form insoluble purple complexes [CrCl3(PR3)]n, which are probably polymeric, with halogen bridging. Treatment of the green complexes [CrCl3(PR3)2]2 with Ph4PCI (or in some cases with Ph4AsCl) results in the formation of green salts of the type Ph4P[CrCl4(PR3)2] which are unstable in solution. Their i.r. and electronic spectra (together with spectra of the neutral dimers) show that the anions have trans-octahedral stereochemistry. Assignments for the Cr–Cl and Cr–P stretching frequencies in these complexes are given, together with values for various ligand-field parameters. |
