ORGANOLANTHANOIDS - 23 - COMPLEXES OF TRIS(CYCLOPENTADIENYL)LANTHANOIDS WITH TERTIARY PHOSPHINE OXIDES AND THE X-RAY CRYSTAL-STRUCTURES OF [YBCP3(OPPH3)] AND [NDCP3(OPBU3N)](2)

Treatment of [LnCp(3)(THF)] (Ln=La, Nd, Sm, or Yb) (Cp, cyclopentadien yl and THF, tetrahydrofuran) and [Nd(MeCp)(3)(THF)] (MeCp, methylcyclo pentadienyl) with OPR3 (R=Ph, o-tolyl, Bu-n) in either THF or DME (DME , 1,2-dimethoxyethane) gave the complexes [LnCp(3)(OPPh3)] (Ln=La, Nd, Sm and Yb), [Nd(MeCp)(3)(OPPh3)], [SmCp3(OP(o-tolyl)(3))], [Nd(MeCp)( 3)(OP(o-tolyl)(3))], and [LnCp(3)(OPBu3n)] (Ln=La, Nd). An attempt to react [GdCp3(THF)] with OPPh3 in either THF or DME crystallised unsolv ated GdCp3, whilst a mixture of [GdCp3(OPPh3)] and OPPh3 was recovered from the filtrate. Attempted synthesis of [YbCp3(OPBu3n)] yielded [{Y bCp2(OPBu3n)}(2)O], the connectivity established by X-ray crystallogra phy, and impure [YbCp3(OPBu3n)]. Single crystal X-ray structure determ ination of [YbCp3(OPPh3)] (monoclinic, space group P2(1), a=8.4187(7), b=17.019(11), c=9.450(7) Angstrom, beta=97.97(6)degrees, Z=2, R=0.043 for 1576 observed data) showed the complex to contain formal ten coor dinate ytterbium with distorted pseudo tetrahedral stereochemistry whi lst the structure of [NdCp3(OPBu3n)] (trigonal, space group P31/c, a=b =12.973(4), c=9.657(6) Angstrom, Z=2, R=0.052 for 602 observed data) s howed ten coordinate neodymium with a distinctly trigonal pyramidal ar rangement of oxygen and the centroids (Ct) of the Cp rings (Ct-Nd-Ct 1 19.8 degrees). (C) 1998 Elsevier Science S.A. All rights reserved.