Lanthanide Phosphido Complexes: A Comparison of the Divalent Homoleptic Species Ln[(μ-PtBu2)2Li(thf)]2 (Ln = Yb, Eu, Sm) Including the Structural Characterization and a Europium-151 Mössbauer Spectrum of Eu[(μ-PtBu2)2Li(thf)]21

Abstract

A comparison of the three isostructural homoleptic lanthanide phosphide species Ln[(&mgr;-P(t)Bu(2))(2)Li(thf)](2) [Ln = Yb (1), Eu (2), Sm (3)] is reported. Eu(OSO(2)CF(3))(3) reacts with 5 equiv of LiP(t)Bu(2) in tetrahydrofuran to give the europium complex Eu[(&mgr;-P(t)Bu(2))(2)Li(thf)](2) (2) in 50% yield plus 0.5 equiv of (t)Bu(2)P-P(t)Bu(2). 2 crystallizes in space group P2(1)/c. Crystal data for 2 at 248 K: a = 21.740(3) Å, b = 12.345(1) Å, c = 20.633(2) Å, beta = 109.13(1) degrees; V = 5231.5(10) Å(3); Z = 4; D(calcd) = 1.131 g cm(-)(3); R(F)() = 3.29%. The molecular structure shows the four-coordinate europium atom in a distorted tetrahedral environment. A main feature of the crystal structure of 2 is the shortest Eu-P distance [3.034(1) Å] of divalent europium reported so far. A (151)Eu Mössbauer spectrum at 4.2 K is reported exhibiting an isomer shift of -11.7 mm/s.