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Ligand selection requires critical consideration in many practical areas, including bioinorganic and medicinal chemistry, homogeneous catalysis, and environmental chemistry. Ligands are classified in many ways, including: charge, size (bulk), the identity of the coordinating atom(s), and the number of electrons donated to the metal ( denticity ...
Thus, only a single ν CO band is observed in the IR spectra of the octahedral metal hexacarbonyls. Spectra for complexes of lower symmetry are more complex. For example, the IR spectrum of Fe 2 (CO) 9 displays CO bands at 2082, 2019 and 1829 cm −1. The number of IR-observable vibrational modes for some metal carbonyls are shown in the table.
When given a metal complex and the trends for the ligand types, the complex can be written in a more simplified manner with the form [ML l X x Z z] Q±. The subscripts represent the numbers of each ligand type present in that complex, M is the metal center, and Q is the overall charge on the complex. Some examples of this overall notation are ...
In the covalent bond classification method, κ 1-carbonate is anX ligand and κ 2-carbonate is an X 2 ligand. With two metals, the number of bonding modes increases because carbonate often serves as a bridging ligand. It can span metal-metal bonds as in [Ru 2 (CO 3) 4 Cl 2] 5-, where again it functions as an (X) 2 ligand.
Co(CO) 3 (NO) is a stable 18-electron complex in part due to the bonding of the NO ligand in its linear form. The donation of the lone pair on the nitrogen makes this complex ML 4 X, containing 18 electrons. The traditional coordination number here would be 4, while the CBC more accurately describes the bonding with a LBN of 5.
Compounds that obey the 18-electron rule are typically "exchange inert". Examples include [Co(NH 3) 6]Cl 3, Mo(CO) 6, and [Fe(CN) 6] 4−. In such cases, in general ligand exchange occurs via dissociative substitution mechanisms, wherein the rate of reaction is determined by the rate of dissociation of a ligand. On the other hand, 18-electron ...
Many rules in chemistry rely on electron-counting: Octet rule is used with Lewis structures for main group elements, especially the lighter ones such as carbon, nitrogen, and oxygen, 18-electron rule [2] in inorganic chemistry and organometallic chemistry of transition metals, Hückel's rule for the π-electrons of aromatic compounds,
In coordination chemistry, a bridging ligand is a ligand that connects two or more atoms, usually metal ions. [1] The ligand may be atomic or polyatomic. Virtually all complex organic compounds can serve as bridging ligands, so the term is usually restricted to small ligands such as pseudohalides or to ligands that are specifically designed to ...