ESR matrix isolation investigation of the aluminum hydride radical cation−AlH+

The AlH+ radical cation has been trapped in a neon matrix at 4 K and studied via electron spin resonance spectroscopy (ESR). The magnetic parameters are Al: A∥=1009(3), A⊥=877(3) and H: A∥=A⊥=283(3) MHz; g∥=2.002(1) and g⊥=2.000(1). The isotropic and dipolar hyperfine components were calculated from ab initio CI and SCF type wave functions for comparison with experimental results. AlH+ is the first paramagnetic molecular cation studied via rare gas matrix isolation ESR spectroscopy.