SYNTHESIS, X-RAY CRYSTAL-STRUCTURE DETERMINATION, AND NMR SPECTROSCOPIC INVESTIGATION OF 2 HOMOLEPTIC 4-COORDINATE LANTHANIDE COMPLEXES - TRIVALENT ((T)BU(2)P(2))(2)LA[(MU-P(T)BU(2))(2)LI(THF)] AND DIVALENT YB[(MU-P(T)BU(2))(2)LI(THF)](2)

La(OSO2CF3)(3) reacts with 4 equiv of LiP(t)Bu(2) in tetrahydrofuran t o give dark red ((t)Bu(2)P)(2)La[(mu-P(t)Bu(2))(2)Li(thf)](2) (1). Yb( OSO2CF3)(3) reacts with LiP(t)Bu(2) in tetrahydrofuran in a 1:5 ratio to produce Yb[(mu-P(t)Bu(2))(2)Li(thf)](2) (2) and 1/2 an equiv of (t) Bu(2)P-P(t)Bu(2). Both 1 and 2 crystallize in the monoclinic space gro up P2(1)/c. Crystal data for 1 at 214 K: a = 11.562 (1) Angstrom, b = 15.914 (1) Angstrom, c = 25.373 (3) Angstrom, beta = 92.40 (1)degrees; V = 4664.5 Angstrom(3); Z = 4; D-calcd = 1.137 g cm(-3); R(F) = 2.61% . Crystal data for 2 at 217 K: a = 21.641 (2) Angstrom, b = 12.189 (1) Angstrom, c = 20.485 (2) Angstrom, beta = 109.01 (1)degrees; V = 5108 .9 Angstrom(3); Z = 4; D-calcd = 1.185 g cm(-3); R(F) = 2.80%. The mol ecular structures of 1 and 2 show the four-coordinate lanthanide atoms in distorted tetrahedral environments. These complexes are the first representatives of the lanthanide elements surrounded by four only-pho sphorus-containing substituents. The main features of the crystal stru cture of 1 are the shortest La-P distances (2.857(1) and 2.861(1) Angs trom) reported so far and a three-coordinate lithium cation. The molec ular structure of 2 represents a divalent his ''ate'' complex with two three-coordinate lithium cations. Complex 2 shows photoluminescent pr operties. VT NMR spectra (Li-7 and P-31) are reported for 1 and 2.