Chapter 1 serves as an introduction to the concept of carbon monoxide releasing molecules (CORMs) and their potential therapeutic applications. Previous work based on transition metal carbonyl complexes is explored. This is followed by a brief outline of the techniques used such as matrix isolation (MI) and picosecond time resolved infrared (psTRIR) spectroscopy. Chapter 2 describes the synthesis and characterisation of methoxy-based chromium and tungsten Fischer carbene complexes. Their potential as CO delivery systems is assessed by investigating their photochemical and photophysical properties to underpin the mechanism of CO release. A novel CO release trigger, electrochemically induced CO loss is described, monitored by gas chromatography (GC). Chapter 3 is based on a study of amino-substituted Fischer carbene complexes. The synthesis and investigation of their CO releasing abilities using photochemical, thermal and electrochemical approaches is explored. The photochemical and thermal CO releasing potential was indicated using the myoglobin assay and quantified via headspace analysis by GC. PsTRIR spectroscopy was used to probe the early state dynamics leading to CO loss. Electrochemically induced CO loss, using bulk electrolysis was also determined. Finally, the effects of different solvents on CO release were investigated. Chapter 4 involves the synthesis and characterisation of a range of novel and previously reported ferrocenyl- and styryl- based Fischer carbene complexes. The photochemistry of the complexes were investigated using psTRIR spectroscopy. Electrochemically induced CO release was also assessed. Chapter 5 highlights the synthesis and characterisation of a range of novel boron dipyrromethene (BODIPY) metal carbonyl complexes. The photophysical properties and electrochemical properties are reported. The photochemically activated CO releasing ability of these complexes is quantified in biologically compatible media using gas chromatography.