PREPARATION AND X-RAY STRUCTURES OF K[LN(O-2,6-I-PR2C6H3)4] (LN=LA, ND, ER) - EXTENDED-CHAIN STRUCTURES OF LANTHANIDE TETRAKIS(ARYLOXIDE) ANIONS BRIDGED BY POTASSIUM-ETA-ARENE INTERACTIONS

Reaction of several lanthanide trichlorides LnCl(3) (Ln = La, Nd, Er, Lu) with 3 or 4 equiv of potassium 2,6-diisopropylphenoxide in THF sol ution leads to the formation of potassium salts of formula K[Ln(O-2,6- i-Pr2C6H3)(4)] [Ln = Nd (5), Er (6), Lu (7), La(8)]. These salts exhib it unusual solid-state structures involving multihapto potassium-pi-ar ene interactions. Not all lanthanide trichlorides produce the potassiu m salt directly from this reaction, and the nature of the product appe ars to be related to the solubility of the LnCl(3) starting material i n THF solution. Compounds 5 and 6 exist in the solid state as pseudo-o ne-dimensional infinite-chain structures featuring multihapto K-C inte ractions with phenyl rings from two adjacent [Ln(OAr)(4)](-) units. Co mpound 8 forms a pseudo-two-dimensional sheet structure, with multihap to K-C interactions linking three neighboring [Ln(OAr)(4)](-) units. L n-O distances within the tetrahedral [Ln(OAr)(4)](-) units average 2.2 11(12) (5), 2.084(14) (6) and 2.253(6) Angstrom (8). Potassium-carbon distances of the arene rings are in the ranges 3.097(8)-3.772(11) Angs trom (5), 3.018(8)-3.484(10) Angstrom (6) and 3.089(3)-3.519(4) Angstr om (8). Crystal data for 5 (at -171 degrees C): monoclinic space group P2(1)/n, a = 12.990(4) Angstrom, b = 18.977(6) Angstrom, c = 18.594(5 ) Angstrom, beta = 93.94(1)degrees, V = 4572.66 Angstrom(3), d(calc) = 1.296 g cm(-3), Z = 4, R = 0.0538, R(W) = 0.0530. Crystal data for 6 (at -161 degrees C): monoclinic space group P2(1)/n, a = 10.567(3) Ang strom, b = 20.856(6) Angstrom, c = 20.938(6) Angstrom, beta = 102.72(1 )degrees V = 4500.93 Angstrom(3), d(calc) = 1.351 g cm(-3), Z = 4, R = 0.0362, R(W) = 0.0368. Crystal data for 8 (at -171 degrees C): orthor hombic space group Pcab, a = 19.153(2) Angstrom, b = 20.898(3) Angstro m, c = 22.673(3) Angstrom, V = 9074.66 Angstrom(3), d(calc) = 1.299 g cm(-3), Z = 8, R = 0.0272, R(W) = 0.0281.