Relationship between the bite size of diphosphine ligands and tetrahedral distortions of square-planar nickel(II) complexes: Stabilization of nickel(I) and palladium(I) complexes using diphosphine ligands with large bites

Journal Article · Tue Feb 05 23:00:00 EST 1991 · Inorganic Chemistry; (United States)

DOI:https://doi.org/10.1021/ic00003a012· OSTI ID:6034372

Miedaner, A; DuBois, D L ^[1]; Haltiwanger, R C ^[2]

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1. Solar Energy Research Inst., Golden, CO (USA)
2. Univ. of Colorado, Boulder (USA)

Nickel and palladium complexes of the type (M(L{sub 2}){sub 2})(BF{sub 4}){sub 2} and (M(L{sub 2})(L{sub 2}{prime}))(BF{sub 4}){sub 2} (where L{sub 2} and L{sub 2}{prime} are diphosphine ligands) have been synthesized. The lowest energy electronic absorption band for the nickel complexes decreases in energy as the bite size of the diphosphine ligand increases. Similarly, the half-wave potentials for the Ni(II/I) and Pd(II/O) couples become more positive as the bite size increases. Structural studies of (Ni(dppm){sub 2})(BF{sub 4}){sub 2} (where dppm is bis(diphenylphosphino)methane) and (Ni-(dppb){sub 2})(PF{sub 6}){sub 2} (where dppb is 1,2-bis(diphenylphosphino)benzene) show that increasing the bite size of the diphosphine ligands results in larger tetrahedral distortions. The crystal structure of (Ni(Dppm){sub 2})(BF{sub 4}){sub 2}(C{sub 50}H{sub 44}B{sub 2}F{sub 8}NiP{sub 4}) and (Ni(Dppb){sub 2})(PF{sub 6}){sub 2}(C{sub 74}H{sub 64}F{sub 12}NiP{sub 6}) were measured and are reported herein. Calculations made using the extended Huckel theory indicate that the observed distortions may have an electronic as well as a steric component. The calculations also allow rationalization of the electronic absorption spectra, electrochemical data, and the stability of the Ni(I) and Pd(I) complexes (Ni(dppp){sub 2})(BF{sub 4}) (where dppp is 1,3-bis(diphenylphosphino)propane) and (Pd(dppx){sub 2})(BF{sub 4}) (where dppx is {alpha},{alpha}{prime}-bis(diphenylphosphino)-o-xylene). Complexes containing the ligand dppm have a marked tendency to become five-coordinate, as indicated by the structural determination of (Ni(dppm){sub 2}(CH{sub 3}CN))(PF{sub 6}){sub 2}. The crystal structure for the latter complex is reported.

• OSTI ID: 6034372
• Journal Information: Inorganic Chemistry; (United States), Journal Name: Inorganic Chemistry; (United States) Vol. 30:3; ISSN 0020-1669; ISSN INOCA
• Country of Publication: United States
• Language: English

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ALKENES
AROMATICS
BORON COMPOUNDS
BORON FLUORIDES
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CATALYSIS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
CHEMISTRY
COMPLEXES
CRYSTAL STRUCTURE
DATA
DIMERIZATION
ELECTROCHEMISTRY
ETHYLENE
EXPERIMENTAL DATA
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
HYDROCARBONS
INFORMATION
NICKEL COMPLEXES
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PALLADIUM COMPLEXES
PHOSPHINES
PHOSPHORUS COMPOUNDS
POLYMERIZATION
REDUCTION
SYNTHESIS
TRANSITION ELEMENT COMPLEXES