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Unsaturated Bis(phosphido)‐bridged Heterobimetallic Polyhydrides via Dihydrogen Activation
Author(s) -
Thomas Baker R.,
Glassman Timothy E.,
Ovenall Derick W.,
Calabrese Joseph C.
Publication year - 1991
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.199100005
Subject(s) - chemistry , medicinal chemistry , catalysis , triphenylphosphine , homogeneous , stereochemistry , organic chemistry , physics , thermodynamics
Hydrogenation (1 atm) of (PCy 2 ) 2 Re(μ‐PCy 2 ) 2 M(1,5‐COD) (M = Rh, Ir; Cy = cyclohexyl; COD = cyclooctadiene), (PCy 2 ) 2 Re(μ‐PCy 2 ) 2 Rh(DMPE) (DMPE = [Me 2 PCH 2 ] 2 ), [(PCy 2 ) 2 ReH(μ‐PCy 2 ) 2 Rh(DMPE)]BF 4 and (PCy 2 ) 2 ReH(μ‐PCy 2 ) 2 Pd‐(PPh 3 ) proceeds stepwise with initial additions of H 2 across the Re = P multiple bonds to give ReH(PCy 2 H) moieties. Further addition of H 2 occurs only for M = Rh. The DMPE complex gives the tetrahydride (PCy 2 H) 2 ReH 3 (μ‐PCy 2 ) 2 RhH(DMPE), which loses PCy 2 H at 80 °C to give (PCy 2 H)ReH 4 (μ‐PCy 2 ) 2 Rh(DMPE). Hydrogenation of the COD complex affords the stable hexahydride (PCy 2 H)ReH 5 (μ‐PCy 2 ) 2 RhH(PCy 2 H) via the cyclooctenyl complex. (PCy 2 ) 2 ReH(μ‐PCy 2 ) 2 Rh(η 3 ‐C 8 H 13 ). While the hexahydride is an active homogeneous catalyst precursor for the hydrogenation of alkenes, dienes, and alkynes, attempts to activate the Re center for C‐H bond activation have not yet been successful. 31 P and 1 H DNMR spectroscopy have been used to investigate the solution dynamics of the heterobimetallic polyhydrides, and several X‐ray diffraction studies serve to define the solid state structures.