The anion part of R 2 is derived from a Lewis acid catalyst and the best formula (MX (VI + 1 R2T) - (4), where M represents the electronegativity value of an element in the range of paulin from 1.0 to 2.0, R2 is an alkyl group with up to 12 carbon atoms, V is the valence oxidation state of the element or m and 0 < T < v. Although the value of T is preferably zero, alkyl groups can be included. The preferred Lewis acid anion contains halide x, which is the same as the halide in the cation part of phosphine nitrile, i.e. the most preferred one is chlorine. M element of Lewis acid part is a kind of electropositive element. According to Pauling's scale, from 1 to 2, preferably from 1.2 to 1.9, preferably from 1.5 to 1.9, with electronegativity. There are suitable elements in IB, ILA, IIB, iila, IVA, IVB, VA, VB, VIB, vilb and ill groups of periodic table. They include aluminum, boron, magnesium, antimony and silicon.<br>
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