The propensity for H2 activation in this system proved sensitive to the precise sterics of the ligand environment on zinc and reaction of 1b, bearing smaller aryl flanking groups, with [Fe(η 5 -C5H5)(CO)2]2 led to the immediate formation of 2b with elimination of dihydrogen at 25 °C (Scheme 1c). A control reaction was conducted in which 2b was exposed to H2 in the presence of light. However, no hydride-containing products were detected at short reaction times (1 bar H2, 1-6 hours) nor long exposure times (24 hours) and under high H2 pressures (4 bar).