Infrared spectra and density functional calculations of triplet pnictinidene N÷ThF3, P÷ThF3 and As÷ThF3 molecules

Abstract

Thorium atoms react with NF(3), PF(3), and AsF(3) to produce the first actinide triplet state pnictinidene molecules, N divided by ThF(3), P divided by ThF(3), and As divided by ThF(3), which are trapped in solid argon and identified from infrared spectra and comparison to computed vibrational frequencies. Density functional theory calculations for these lowest energy triplet state products converge essentially to C(3v) symmetry structures. Spin density calculations show that the two unpaired electrons are mostly localized in nitrogen 2p, phosphorus 3p, or arsenic 4p orbitals. Although thorium has a small spin density, the weak degenerate pi(alpha) molecular orbitals are populated entirely from the terminal N, P, or As based on DFT natural bond orbital analysis. This is in contrast with HC divided by ThF(3), which contains degenerate pi(alpha) molecular orbitals with 81% C and 19% Th character.