Heating of a mixture of [Ni(CH2CH2)(dtbpe)] (dtbpe = 1,2-bis(di-tert-butylphosphino)ethane)
and 2,6-dimesitylphenylphosphine (DmpPH2) in toluene gives
the secondary phosphine (Dmp)P(Et)(H) (1) as the main
product. However, thermolysis of [Ni(CH3)2(dtbpe)]
in the presence of DmpPH2 in toluene leads to the mononuclear
nickel phosphanido hydride complex [NiH{P(Dmp)(H)}(dtbpe)] (2), the product of an oxidative addition of a primary phosphine
to nickel(0). The structure of complex 2 was confirmed
by single-crystal X-ray diffraction and DNMR studies. The mutual exchange
of tautomers in which the Ni–H and P–H hydrogen atoms
interchange as well as the position of the hydrido and the phosphanido
ligand occurs in solution. The stoichiometric reaction of 2 with 1-hexene proceeds regiospecifically to form the secondary phosphine
(Dmp)P(Hex)(H) (3).