Early atomic transition metal cations reacting with ammonia at room temperature: H2 elimination and NH3 ligation kinetics across and down the periodic table

•Measured ligation kinetics of early atomic transition metal cations (3 rows, Groups 3–9) with ammonia.•Observed competition between ligation and H2 elimination (imide bond formation).•Three of the 3rd row MNH+ cations (M = Ta+, W+ and Os+) revealed the rapid formation of a second imido bond to produce M(NH)2+.•Comparisons with previous theoretical predictions.•Tracked periodic trends in rates and product formation with overview of atomic orbital filling effects.