[Re(CO)Br(CNArDArF2)4] and [Tc(CO)Cl(CNArDArF2)4] (ArDArF = 2,6-(3,5-(CF3)2C6H3)2-4-F-C6H2) were prepared by reactions of [Re(CO)5Br] or (NBu4)[Tc2(CO)6(μ-Cl)3] with the sterically encumbered isocyanide CNArDArF2. These two compounds proved to be excellent starting materials for the synthesis of unprecedented low-valent rhenium and technetium complexes. The reduction of [Re(CO)Br(CNArDArF2)4] with Na/Hg produces an equimolar mixture of [Re(CO)(CNArDArF2)4] and Na[Re(CO)(CNArDArF2)4] containing the transition metal in the formal oxidation states “0” and “–1”, respectively. The reduction of [Tc(CO)Cl(CNArDArF2)4] with Na/Hg produces Na[Tc(CO)(CNArDArF2)4], which was characterized by 19F and 99Tc NMR spectroscopy. The reactivity of Na[Re(CO)(CNArDArF2)4] resembles that of [Re(CO)5]−, proved by reactions with a number of electrophiles such as MeI, HCl, or F6C5C(O)Cl.