Metal Nitrosyls:
Metal nitrosyls are coordination compounds that contain a metal atom bonded to a nitric oxide (NO) ligand. The metal-nitric oxide bond in these compounds is highly polar and exhibits a significant degree of covalent character. Metal nitrosyls have attracted significant attention in the field of inorganic chemistry due to their unique bonding properties and diverse reactivity.

Properties and Structure:
Metal nitrosyls can exist in various oxidation states, and their structures can be highly complex. The metal center is typically a transition metal, such as iron, cobalt, nickel, or ruthenium. The nitric oxide ligand, NO, acts as a neutral ligand and can coordinate to the metal center in different ways, such as through the nitrogen atom (N-bound) or the oxygen atom (O-bound). The coordination geometry around the metal center can vary, ranging from linear to tetrahedral to octahedral.

Bonding and Reactivity:
The metal-nitric oxide bond in metal nitrosyls is primarily formed through the donation of electron density from the filled d-orbitals of the metal to the antibonding π*-orbitals of the nitric oxide ligand. This back-donation of electrons leads to the formation of a coordinate covalent bond. The metal-nitric oxide bond is known to be highly labile, and metal nitrosyls can undergo various reactions, including ligand substitution, oxidative addition, and reductive elimination.

Applications:
Metal nitrosyls have found applications in a variety of areas, including catalysis, bioinorganic chemistry, and medicinal chemistry. They can serve as versatile ligands in transition metal complexes, influencing the reactivity and selectivity of catalytic reactions. Metal nitrosyls have also been explored as potential therapeutic agents, owing to their ability to interact with biological targets and exhibit cytotoxic effects.

Classification of Metal Carbonyls:
Metal carbonyls are another class of coordination compounds that contain a metal atom bonded to one or more carbon monoxide (CO) ligands. The metal-carbonyl bond in these compounds is highly polar and exhibits a significant degree of covalent character. Metal carbonyls have been extensively studied due to their unique bonding properties and diverse reactivity.

Properties and Structure:
Metal carbonyls can exist in various oxidation states, and their structures can range from simple mononuclear complexes to more complex multinuclear clusters. The metal center is typically a transition metal, such as iron, cobalt, nickel, or chromium. The carbon monoxide ligands, CO, act as neutral ligands and can coordinate to the metal center in different ways, such as through the carbon atom (C-bound) or the oxygen atom (O-bound). The coordination geometry around the metal center can vary, ranging from linear to trigonal planar to tetrahedral.

Bonding and Reactivity:
The metal-carbonyl bond in metal carbonyls is primarily formed through the donation of electron density from the filled d-orbitals of the metal to the antibonding π*-orbitals of the carbon monoxide ligands. This back-donation of electrons leads to the formation of coordinate covalent bonds. The metal-carbonyl bonds are known to be labile