Dimerization mechanism of bis(triphenylphosphine)copper(I) tetrahydroborate: proton transfer via a dihydrogen bond.
The mechanism of transition-metal tetrahydroborate dimerization was established for the first time on the example of (Ph(3)P)(2)Cu(η(2)-BH(4)) interaction with different proton donors [MeOH, CH(2)FCH(2)OH, CF(3)CH(2)OH, (CF(3))(2)CHOH, (CF(3))(3)CHOH, p-NO(2)C(6)H(4)OH, p-NO(2)C(6)H(4)N═NC(6)H(4)OH, p-NO(2)C(6)H(4)NH(2)] using the combination of experimental (IR, 190-300 K) and quantum-chemical (DFT/M06) methods. The formation of dihydrogen-bonded complexes as the first reaction step was established experimentally. Their structural, electronic, energetic, and spectroscopic features were thoroughly analyzed by means of quantum-chemical calculations. Bifurcate complexes involving both bridging and terminal hydride hydrogen atoms become thermodynamically preferred for strong proton donors. Their formation was found to be a prerequisite for the subsequent proton transfer and dimerization to occur. Reaction kinetics was studied at variable temperature, showing that proton transfer is the rate-determining step. This result is in agreement with the computed potential energy profile of (Ph(3)P)(2)Cu(η(2)-BH(4)) dimerization, yielding [{(Ph(3)P)(2)Cu}(2)(μ,η(4)-BH(4))](+).
A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences (INEOS RAS), 28 Vavilov Street, 119991 Moscow, Russia.
Igor E
IE
Golub
Oleg A
OA
Filippov
Evgenii I
EI
Gutsul
Natalia V
NV
Belkova
Lina M
LM
Epstein
Andrea
A
Rossin
Maurizio
M
Peruzzini
Elena S
ES
Shubina
D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000737:chemistry; D019281:Dimerization; D006860:Hydrogen Bonding; D008968:Molecular Conformation; D010720:Phosphines / Q000138:chemical synthesis* / Q000737:chemistry; D011522:Protons; D011789:Quantum Theory; D013237:Stereoisomerism
D056831:Coordination Complexes; D010720:Phosphines; D011522:Protons