title: Sigma-borane complexes of iridium: synthesis and structural characterization.
abstract: Reaction of NaBH4 with (tBuPOCOP)IrHCl affords the previously reported complex (tBuPOCOP)IrH2(BH3) (1) (tBuPOCOP = kappa(3)-C6H3-1,3-[OP(tBu)2]2). The structure of 1 determined from neutron diffraction data contains a B-H sigma-bond to iridium with an elongated B-H bond distance of 1.45(5) A. Compound 1 crystallizes in the space group P1 (Z = 2) with a = 8.262 (5) A, b = 12.264 (5) A, c = 13.394 (4) A, and V = 1256.2 (1) A(3) (30 K). Complex 1 can also be prepared by reaction of BH3 x THF with (tBuPOCOP)IrH2. Reaction of (tBuPOCOP)IrH2 with pinacol borane gave initially complex 2, which is assigned a structure analogous to that of 1 based on spectroscopic measurements. Complex 2 evolves H2 at room temperature leading to the borane complex 3, which is formed cleanly when 2 is subjected to dynamic vacuum. The structure of 3 has been determined by X-ray diffraction and consists of the (tBuPOCOP)Ir core with a sigma-bound pinacol borane ligand in an approximately square planar complex. Compound 3 crystallizes in the space group C2/c (Z = 4) with a = 41.2238 (2) A, b = 11.1233 (2) A, c = 14.6122 (3) A, and V = 6700.21 (19) A(3) (130 K). Reaction of (tBuPOCOP)IrH2 with 9-borobicyclononane (9-BBN) affords complex 4. Complex 4 displays (1)H NMR resonances analogous to 1 and exists in equilibrium with (tBuPOCOP)IrH2 in THF solutions.
authors.affiliation: Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, USA.
authors.forename: Travis J
authors.initials: TJ
authors.lastname: Hebden
authors.forename: Melanie C
authors.initials: MC
authors.lastname: Denney
authors.forename: Vincent
authors.initials: V
authors.lastname: Pons
authors.forename: Paula M B
authors.initials: PM
authors.lastname: Piccoli
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Koetzle
authors.forename: Arthur J
authors.initials: AJ
authors.lastname: Schultz
authors.forename: Werner
authors.initials: W
authors.lastname: Kaminsky
authors.forename: Karen I
authors.initials: KI
authors.lastname: Goldberg
authors.forename: D Michael
authors.initials: DM
authors.lastname: Heinekey