Syntheses, structural, electrochemical and optical studies of heterobinuclear ruthenium-osmium alkynyl complexes

► Syntheses of Os alkynyl complexes with pendant ethynyl groups were developed. ► Three Os alkynyl complexes with pendant ethynyl groups were structurally characterized. ► Syntheses of heterobinuclear Os-Ru alkynyl complexes were developed. ► Our heterobinuclear Os-Ru alkynyl complexes undergo stepwise reversible oxidation. ► Stepwise oxidation in the Os-Ru complexes is accompanied by strong optical changes.