SYNTHESIS, STRUCTURE, AND REACTIVITY OF HETEROMETALLIC POLYHYDRIDE COMPLEXES OF RHENIUM WITH YTTRIUM AND LUTETIUM

Yttrium and lutetium methyl complexes readily react with rhenium hydride compounds to eliminate methane and form heterometallic polyhydride complexes. The complexes (C5H5)2LnMe(THF) (Ln = Y, Lu) react with ReH7(PPh3)2 and ReH5(PMe2Ph)3 to form (C5H5)2Ln(THF)H6Re(PPh3)2 and (C5H5)2Ln(THF)H4Re(PMe2Ph)3. (C5H5)2Y(THF)H6Re(PPh3)2, 1, crystallizes from 3:1 toluene/THF at -35-degrees-C in space group P2(1)/c (C2h5; No. 14) with a = 19.886 (4) angstrom, b = 9.8014 (15) angstrom, c = 25.815 (5) angstrom, beta = 102.653 (15)-degrees, V = 4909.5 (15) angstrom3, and D(calcd) = 1.49 g cm-3 for Z = 4. Least-squares refinement of the model based on 5022 reflections (F2 > 3.0sigma(F2)) converged to a final R(F) = 5.0%. (C5H5)2Y(THF)H4Re(PMe2Ph)3,2, crystallizes from hexane at -35-degrees-C in space group Pca2(1) (C2v5; No. 29) with a = 21.537 (4) angstrom, b = 11.734 (2) angstrom, c = 30.142 (4) angstrom, V = 7617 (2) angstrom3, and D(calcd) = 1.562 g cm-3 for Z = 8. Least-squares refinement of the model based on 5087 reflections (F2 > 4.0sigma(F2)) converged to a final R(F) = 5.8%. Both 1 and 2 exist as molecular species containing bridging hydride ligands. In each case, the geometry around each metal resembles that in analogous monometallic systems with some distortions arising from steric crowding. The complexes (C5H5)2LnMe(THF) (Ln = Y, Lu) also react with Re2H8(PMe2Ph)4 in THF to form (C5H5)2y(THF)H7Re2(PMe2Ph)4, 3, and (C5H5)2LuH7Re2(PMe2Ph)4, 4. 3 crystallizes from hexane at -35-degrees-C in space group P2(1)/n with unit cell parameters at 213 K of a = 11.9546 (16) angstrom, b = 31.613 (4) angstrom, c = 12.571 (2) angstrom, beta = 92.376 (11-degrees, V = 4746.5 (11) angstrom3, and D(calcd) = 1.712 g cm-3 for Z = 4. Least-squares refinement of the model based on 6616 reflections (F2 > 4.0sigma(F2)) converged to a final RF = 6.1%. 4 crystallizes from hexane at -35-degrees-C in space group P2(1)/c with unit cell parameters at 183 K of a = 16.677 (4) angstrom, b = 12.960 (2) angstrom, c = 19.199 (3) angstrom, beta = 90.990 (16)-degrees, V = 4397.7 (14) angstrom3, and D(calcd) = 1.87 g cm-3 for Z = 4. Least-squares refinement of the model based on 4253 reflections (F2 > 3.0sigma(F2)) converged to a final R(F) = 4.9%. Complex 3 is a fluxional molecule which contains an open L-shaped YRe2 unit. Complex 4 contains a closed triangular LuRe2 core which will not add THF. THF can be removed from 3 to form an yttrium analog of 4. The bimetallic complex 1 is unreactive toward CO, CO2, and PhC=CPh but is highly reactive toward olefin polymerization. In contrast, the trimetallic complexes (C5H5)2LnH7Re2(PMe2Ph)4 are reactive toward CO and CO2 but unreactive with ethylene.