As a matter of fact, whereas PPh3 (h=145°) and PCy3 (h=170°) do not react
with K+[HFe(CO)4]− in ethanol at room temperature, P(n-Bu)3 (h=132°) does
react (even below 5 °C) but does not lead to the corresponding
Fe(CO)3[P(n-Bu)3]2 derivative. Under these conditions, the reaction proceeds with
evolution of 2 equiv. of CO, leading to the dihydride H2Fe(CO)2[P(n-Bu)3]2
(Eq. (4)). Similarly, use of PMe2Ph (h=122°) leads to the dihydride
H2Fe(CO)2[PMe2Ph]2 [26].