89530-30-3Relevant academic research and scientific papers
Binuclear tungsten-iridium acyl hydrides, carbene hydrides, and related complexes. Crystal and molecular structures of WIrH(μ-PPh2)2(CO)5(PPh3) and WIrH(μ-PPh2)2{C(OMe)Ph}(CO)4(PPh 3)
Breen, Michael J.,Shulman, Peter M.,Geoffroy, Gregory L.,Rheingold, Arnold L.,Fultz, William C.
, p. 782 - 793 (2008/10/08)
Reaction of Li[W(CO)5(PPh2)] with trans-IrCl(CO)(PPh3)2 yields the binuclear complex WIr(μ-PPh2)(CO)6(PPh3)2 (1) which has been spectroscopically characterized. Complex 1 reversibly adds H2 and CO at the Ir center concomitant with reversible dissociation of the W-Ir bond. Reaction of Li[W-(CO)4(PPh2H)(PPh2)] with trans-IrCl(CO)(PPh3)2 gives the new complex WIrH(μ-PPh2)2(CO)5(PPh3) (2) which has been structurally characterized. Complex 2 crystallizes in the space group P21/n with a = 11.416 (2) A?, b = 19.129 (5) A?, c = 20.673 (3) A?, β = 100.78 (2)°, V = 4435 (2) A?3, and Z = 4. The structure was refined to R = 0.0332 and Rw = 0.0347 for the 5433 reflections with Fo2 > 3σ(Fo)2. The W and Ir atoms are separated by 2.876 A? and bridged by two μ-PPh2 ligands. The Ir atom is further coordinated by H (located and refined), PPh3, and one CO, and the W center is ligated by four additional CO's. Complex 2 reacts with PhLi and MeLi to give acyl-hydride derivatives [Li(THF)x][WIrH(μ-PPh2)2(CO) 4(PPh3){C(O)R}] (R = Ph (6a), Me (Gb)) with the acyl ligand terminally bound to W and the hydride on Ir. These in turn react with [(CH3)3O]BF4 to give the carbene-hydride complexes WIrH(μ-PPh2)2(CO)4(PPh 3){C(OCH3)R} (R = Ph (7a), Me (7b)) which have been characterized spectroscopically and (7a) by an X-ray diffraction study. The latter crystallizes in the space group P21/n with a = 18.773 (4) A?, b = 20.690 (6) A?, c = 12.761 (4) A?, β = 95.56 (2)°, V = 4933 (2) A?2, and Z = 4. Convergence for the 3408 reflections with Fo2 > 3σ(Fo)2 occurred to give residuals of R = 0.0504 and Rw = 0.0600. The carbene ligand is terminally bound to W which is further ligated by three CO's. The W-Ir bond (2.858 (1) A?) is bridged by the two PPh2 ligands, and the Ir center is further coordinated by the hydride (not located), PPh3, and one CO. Protonation of 6a gives a thermally unstable binuclear hydroxycarbene complex which decomposes above 0°C to release PhCHO. Complex 2 also reacts with Li[BH(sec-Bu)3] to give the dihydride anion [WIrH2(μ-PPh2)2(CO)5(PPh 3)]- which was spectroscopically characterized. The methyl complex WIrCH3(μ-PPh2)2(CO)5(PPh 3) (3) results from the reaction of Li2[W(CO)4(PPh2)2] with trans-IrCl(CO)(PPh3)2 followed by treatment with CF3SO3CH3. Spectroscopic data for 3 imply a structure analogous to 2 with the CH3 ligand bound to Ir.
