Karbonylkomplex

Karbonylkomplex refers to coordination compounds in which carbon monoxide (CO) acts as a ligand. These complexes are formed between a metal atom and one or more carbon monoxide molecules. The carbon monoxide ligand binds to the metal center through a sigma donation from the filled pi orbital of CO to an empty d orbital of the metal, and a pi-backbonding from a filled d orbital of the metal to the empty antibonding pi orbital of CO. This synergistic bonding is crucial for the stability of many carbonyl complexes.

The majority of known metal carbonyls are formed with transition metals, particularly those in the middle and late periods of the d-block. Common metals include iron, cobalt, nickel, chromium, molybdenum, tungsten, manganese, and ruthenium. The number of CO ligands in a complex can vary significantly, leading to mononuclear complexes with a single metal atom, such as Ni(CO)4 and Fe(CO)5, or polynuclear complexes with two or more metal atoms bridged by CO ligands or directly bonded to each other, such as Fe2(CO)9 and Co2(CO)8.

Metal carbonyl complexes exhibit a wide range of oxidation states for the metal, though they are most commonly found in low oxidation states, often zero or negative. This is facilitated by the strong pi-acceptor character of the CO ligand, which can effectively delocalize electron density from the metal. Metal carbonyls are important in various fields, including organometallic chemistry, catalysis (e.g., in hydroformylation and carbonylation reactions), and as precursors for materials science.