Phosphoraneiminato complexes of rare-earth elements. Crystal structures of[Yb2Cp3(NPPh3)(3)], [YCp(NPPh3)(mu-OSiMe2NPPh3)](2), and [M(NPPh3)(2)(mu-OSiMe2NPPh3)](2) with M = Y and Sm

The ytterbium complex [Yb2Cp3(NPPh3)(3)] with sesqui distribution of cyclop entadienide and phosphoraneiminato ligands is made from YbCp2Cl and LiNPPh3 in boiling toluene and isolated as yellow, moisture sensitive crystals, wh ich enclose three molecules of toluene per unit cell. [Yb2Cp3(NPPh3)]. 3C(7 )H(8) (1): Space group Pbca, Z = 8, lattice dimensions at -80 degrees C: a = 2727.6(2), b = 1977.5(1), c = 2848.9(2) pm; R = 0.0541. Two of the (NPPh3 )(-)-groups link the ytterbium atoms to a nonplanar Yb2N2 four-membered rin g with a folding angle of 17.1 degrees along the Yb...Yb connecting line. T he third (NPPh3)(-) group is terminally bonded with a short Yb-N distance o f 214.2 pm. [YCp(NPPh3) (mu-OSiMe2NPPh3)](2). 4C(7)H(8) (2) originates from YCpCl2 and LiNPPh3 in boiling toluene with Baysilon-paste participating forming colour less, moisture sensitive crystals. Space group P2(1)/c, Z = 2, lattice dime nsions at -80 degrees C: a = 1469.0(1), b = 1234.1(1), c = 2761.5(2)pm, bet a = 93.196(10)degrees; R = 0.0518. In 2 the yttrium atoms are linked via th e oxygen atoms of the (OSiMe2NPPh3)(-) groups to form a centrosymmetric Y2O 2 four-membered ring with Y-O bonds of different lengths. Together with the terminally bonded (NPPh3)(-)-ligand, the eta(5)-C5H5- group, and the N ato m of the siloxyphosphaneimine group, which functions as a donor atom, the Y atoms achieve coordination number five. [Y(NPPh3)(2)(mu-OSiMe2NPPh3)](2). 2C(7)H(8) (3) and [Sm(NPPh3)(2)(mu-OSiMe2NPPh3)](2) (4) originate from the metal trichlorides with KNPPh3 in THF with Baysilon paste participating and subsequent crystallization from toluene as colourless, moisture sensitive crystal needles. 3: Space group P2(1)/n, Z = 2, lattice dimensions at -80 d egrees C: a = 1804.1(2), b = 1401.8(1), c = 2221.6(2) pm, beta = 98.716(9)d egrees; R = 0.0537. 4: Space group <P(1)over bar >, Z = 1, lattice dimensions at -80 degrees C: a = 1363.4(1), b = 1364.9(1), c = 1650.6(1) pm; alpha = 112.457(8)degrees beta = 91.948(9)degrees, gamma = 114.974(8)degrees; R = 0.0308. 3 and 4 form centrosymmetric dimeric molecules in which the metal atoms are linked via the oxygen atoms of the (OSiMe2NPPh3)(-) groups to form M2O2 fo ur-membered rings with M-O bonds of varying length. Together with the termi nally bonded (NPPh3)(-) ligands and the N atom of the siloxyphosphaneimine ligand, which functions as a donor atom, the metal atoms achieve coordinati on number five.