Reinvestigation of the Reaction of (NH4)2[Ce(N03)6] with Triphenylphosphine Oxide; the Crystal Structure and Magnetic Properties of mer-Ce(NO3)3(OPPh3)3 • 2 (CH3)2CO

The reaction of (NH4)2[Ce(NO3)6 ] with two equivalents of OPPh3(Ph = C6H5 ) in acetonitrile yields Ce(NO3 ) 4(OPPh3 )2 (1) in high yield, whereas using acetone as solvent affords mer- Ce(NO3 )3(OPPh3)3 • 2(CH3)2CO (2), the yield of which is dependent on the reaction time. A crystal structure determination of 2 shows that the Ce atom is coordinated with three bidentate nitrato groups and three OPPh3 ligands, thus achieving a coordination number of nine. Eight non-coordinating acetone molecules are present in the unit cell. Crystal data (292 K): space group P21/n (no. 14), 0=12.438(2), b = 25.532(4), c = 20.379 (4) Å, β = 96.33(2)°, V = 6432(1) , Z = 4, dcalc = 1.318 g em 3. Due to poor crystal quality the refinement converges at R = 0.11, Rw = 0.09. 2 is paramagnetic, but it does not follow the Curie-Weiss law at low temperature. Therefore crystal field theory was used in order to explain these findings.