The active sites of several bioenergetically important metalloenzymes that perform multielectron redox reactions feature heterobimetallic complexes. Herein, we review recent understanding of the structure and mechanisms of hydrogenases, formate dehydrogenases, and carbon monoxide dehydrogenases. Then we evaluate progress toward creating functional, small-molecule complexes that reproduce the activities of these active sites. Particular emphasis is placed on comparing catalytic properties including turnover number, turnover frequency, required overpotential, and catalyst stability. Opportunities and challenges for future work are also considered.