As–P vs. P–P Insertion in AsP 3 : Kinetic Control of the Formation of [AsP 3 NO] +

The synthesis of mixed arsenic phosphorus cations was investigated on theoretical and experimental grounds by replacing P 4 with AsP 3 in the known syntheses of [P 4 NO] + and [P 9 ] + . Calculations of [AsP 3 NO] + and [AsP 8 ] + showed that 1‐[AsP 3 NO] + and 3‐[AsP 8 ] + should be the most stable isomers. However, 2‐[AsP 3 NO] + was prepared by reacting [NO] + [Al(OR F ) 4 ] – (R F = C(CF 3 ) 3 ) with AsP 3 with a regioselectivity of 45:1. The kinetic control of this reaction was proven by calculation of the complete reaction mechanism. Examination of the formation energetics of the [As x P 4–x NO] + (x = 0, 1, 4) and [As x P 9‐x ] + (x = 0, 1, 9) cations at the CCSD(T)/complete basis set limit level showed that for [As x P 4–x NO] + (x = 0, 1, 4), the replacement of phosphorus by arsenic leads to more exergonic formation energetics. For the [As x P 9‐x ] + clusters (x = 0, 1, 9), the reaction to [AsP 8 ] + is slightly more exergonic compared to the synthesis of [P 9 ] + . The calculation of the reaction to the homopolyatomic arsenic cation [As 9 ] + suggested that this reaction will at least be very difficult. Attempts to prepare [As x P 9‐x ] + from AsP 3 as well as [As x ] + from gray arsenic led to the formation of [AsP 3 NO] + , [P 4 NO] + , [P 9 ] + and P 4 in case of [As x P 9‐x ] + and decomposition products (e.g. novel As(OR F ) 3 ) for [As x ] + .