Synthesis And Structures of Di- And Trinuclear Di-terf-butylphosphido And Di- Tert -butylarsenido Complexes of Iridium: X-ray Crystal Structures of [ir(m-f-bu2e)(co)2]2(e = P, As), [ir(f-bu2ph)(co)]2(ai-h)(m-f-bu2p), [ir(f-bu2ph)(co)(m-h)]2(h)(m-f-bu2p), And Ir3(ai-f-bu2p)3(co)5

Thomas C. Wright, Bruce R. Whittlesey

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Abstract

Reaction of Li-f-Bu2P with [Ir(CO)3Cl]„ in THF at -78 °C yields deep red [Ir(fi-f-Bu2P)(CO)2]2(1) in ca. 35% yield. This complex has a planar central Ir2P2 core with an Ir-Ir double bond (Ir-Ir = 2.545 (1) A). Each Ir atom bears two CO units and has a distorted tetrahedral geometry. The /-Bu2As analogue of 1, yellow [Ir(ji-f-Bu2As)(CO)2]2(2), is produced in 12% yield in the reaction of Ir4(CO)12with /-Bu2AsH in refluxing toluene. In contrast to 1, 2 has two Ir(I) atoms that have planar coordination geometries and no Ir-Ir bond (Ir-Ir = 3.89 (1) A). Reaction of Ir4(CO)12with ?-Bu2PH in toluene under reflux yields the dinuclear hydrido- and phosphido-bridged complex [Ir(f-Bu2PH)(CO)]20t-H)(M-f-Bu2P) (4) (52%) as well as the trinuclear cluster Ir3(ju-f-Bu2P)3(CO)5(3) (24%). 3 consists of an Ir3 triangle that bears one f-Bu2P unit severely distorted from the Ir3 plane and bridges two Ir atoms that bear two CO units each. The third Ir atom has only one CO group. The two other p-t-Bu2P units lie much closer to the Ir3 plane. 4 has two roughly planar Ir atoms (Ir-Ir = 2.901 (1) A) bridged by H and f-Bu2P. The terminal f-Bu2PH groups lie cis with respect to the Ir-Ir interaction and are trans to the ix-t-Bu2P” unit. They occupy the same side of the molecule as the m-hatom. 4 reacts reversibly with H2 (1 atm) in both solution and the solid state to give [Ir(f-Bu2PH)(CO)(M-H)]2-(h)(m-t-bu2P) (5), which contains two bridging hydrides and one terminal hydride. 4 reacts with CO (1 atm) to replace one f-Bu2PH ligand and give (f-Bu2PH)(CO)Ir(M-H)(M-f-Bu2P)Ir(CO)2 (6), The structures of 1–5 have been determined by sin-gle-crystal X-ray diffraction studies. CAD-4 crystal data: (Mo Ka) (graphite monochromator) - 0.71073 A. Crystal data for 1: C20H36Ir2O4P2, MT 768.4, orthorhombic, Pnnm (No. 58), a = 8.535 (1) A, b = 11.990 (1) A, c = 12.574 (2) A, V= 1286.8 (5) A3, Z = 2, Z)calcd * 2.03 g cm”3, m(moka) = 208.7 cm”1, final R = 0.0301 (Rw= 0.0382) from 954 observed (/ > 3<r(/» reflections (1331 measured). Crystal data for 2: C20H36As2Ir2O4, Mx 874.6, monoclinic, C2/m (No. 12), a = 12.009 (2) A, b = 11.214(2) A, c = 11.087 (2) A, (3 = 120.26 (2)°, V= 1289.6 (5) A3, Z = 2, Dealcd = 2.25 g cm”3, fx(Mo Ka) = 128.34 cm”1, final R = 0.0392 (Rw = 0.0589) from 978 observed (/ > 3tr(/)) reflections (1246 measured). Crystal data for 3: C29H54Ir305P3, Mt 1151.6, monoclinic P2\\\\\\\\/c (No. 14), a = 19.753 (6) A, b = 11.796 (5) k,c- 17.116 (6) A, 0 = 113.11 (9)°, V= 3668.1 (5) A3, Z = 4, Dcajod = 2.01 g cm-3, fi(Mo Ka) = 112.65 cm”1, final R ~ 0.039, Rw= 0.048 from 1782 observed reflections (/> 3cr(/)), 2701 measured. Crystal data for 4: C32H71Ir202P3, Afr965.24, orthorhombic, P212121 (No. 19), a - 12.257 (9) A, b = 15.224 (4) A, c = 22.241 (8) A, V = 4150.0 (5) A3, Z = 4, DM= 1.545 g cm”3, m(moKa) = 65.20 cm”1, final R = 0.0713 (Rw= 0.0861) from 1833 observed (/ > 3tr(/)) reflections (4104 measured). Crystal data for 5: C26H61Ir202P3, Mv 883.10, monoclinic Pljc (No. 14), a = 12.341 (2) A, b = 12.313 (4) A, c = 22.597 (9) A, 0 = 92.77 (2)°, V= 3429.9 (5) A3, Z = 4, Dcalcd = 1.710 g cm”3, it(Mo Ka) = 78.80 cm”1, final R = 0.0592 (/?w= 0.0711) from 3436 observed reflections (/ > 3cr(/)), 5346 measured.

Original languageEnglish
Pages (from-to)4065-4073
Number of pages9
JournalInorganic Chemistry
Volume26
Issue number24
DOIs
StatePublished - Dec 1 1987

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