Reaction of H[sub 2] with IrHCl[sub 2]P[sub 2] (P = P[sup i]Pr[sub 3] or P[sup t]Bu[sub 2]Ph). Stereoelectronic control of the stability of molecular H[sub 2] transition metal complexes

Journal Article · Wed Aug 11 00:00:00 EDT 1993 · Journal of the American Chemical Society; (United States)

DOI:https://doi.org/10.1021/ja00069a032· OSTI ID:6835688

Albinati, A ^[1]; Bakhmutov, V I; Gusev, D G; Caulton, K G; Clot, E; Eckert, J; Eisenstein, O; Grushin, V V; Hauger, B E; Klooster, W T ^[2]

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1. Universita de Milano (Italy)
2. and others

IrHCl[sub 2]P[sub 2] (P = P[sup i]Pr[sub 3]) reacts rapidly with H[sub 2] at 25[degrees]C to set up an equilibrium where H[sub 2] binds trans to the original hydride ligand (trans-2). A second slower reaction forms IrH(H[sub 2])Cl[sub 2]P[sub 2] (cis-2), where the cis disposition of the chlorides, and also H cis to H[sub 2], was established by neutron diffraction. This molecule (unlike trans-2), shows rapid site exchange between coordinated H and H[sub 2]. cis-2 can be induced to lose HCL to form Ir(H)[sub 2]ClP[sub 2]. The structure of Ir(H)[sub 2]Cl(P[sup t]Bu[sub 2]Ph)[sub 2], an analog of 3, was shown by neutron diffraction to have a planar H[sub 2]IrCl in a Y shape, with Cl at the base of the Y and a H-Ir-H angle of only 73[degree]. ECP ab initio calculations of IrH[sub 2]Cl(PH[sub 3])[sub 2] show that the Y shape with a H-Ir-H angle close to the experimental value has the minimum energy. They also show that the trans-2 isomer of IrH(H[sub 2])Cl[sub 2](PH[sub 3])[sub 2] is less stable than the cis-2 isomer by 10.3 kcal/mol. The Ir-H[sub 2] interaction is stronger in cis-2. The rotational barrier has been calculated in the two isomers as 2.3 (trans) and 6.5 (cis) kcal/mol. In agreement with the experimental structure, the H-H bond is found to eclipse preferentially the Ir-H bond in cis-2. 74 refs., 12 figs., 5 tabs.

• DOE Contract Number: AC02-76CH00016
• OSTI ID: 6835688
• Journal Information: Journal of the American Chemical Society; (United States), Vol. 115:16; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
08 HYDROGEN
HYDROGEN
CHEMICAL REACTIONS
IRIDIUM COMPLEXES
CRYSTAL STRUCTURE
ELECTRONIC STRUCTURE
MOLECULAR STRUCTURE
STABILITY
ORGANOMETALLIC COMPOUNDS
TRANSITION ELEMENT COMPLEXES
CALCULATION METHODS
CHEMICAL REACTION KINETICS
HYDRIDES
LIGANDS
NEUTRON DIFFRACTION
STEREOCHEMISTRY
COHERENT SCATTERING
COMPLEXES
DIFFRACTION
ELEMENTS
HYDROGEN COMPOUNDS
KINETICS
NONMETALS
ORGANIC COMPOUNDS
REACTION KINETICS
SCATTERING
400201* - Chemical & Physicochemical Properties
080201 - Hydrogen- Chemisorption Storage