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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.
Chromium(II) ion in aqueous solution. Most aquo complexes are mono-nuclear, with the general formula [M(H 2 O) 6] n+, with n = 2 or 3; they have an octahedral structure. The water molecules function as Lewis bases, donating a pair of electrons to the metal ion and forming a dative covalent bond with it. Typical examples are listed in the ...
The carbonyl ligand engages in a wide range of bonding modes in metal carbonyl dimers and clusters. In the most common bridging mode, denoted μ 2 or simply μ, the CO ligand bridges a pair of metals. This bonding mode is observed in the commonly available metal carbonyls: Co 2 (CO) 8, Fe 2 (CO) 9, Fe 3 (CO) 12, and Co 4 (CO) 12.
A ligand exchange (also called ligand substitution) is a chemical reaction in which a ligand in a compound is replaced by another. Two general mechanisms are recognized: associative substitution or by dissociative substitution. A generalized example of ligand association. Associative substitution closely resembles the S N 2 mechanism in organic ...
An example of a dative covalent bond is provided by the interaction between a molecule of ammonia, a Lewis base with a lone pair of electrons on the nitrogen atom, and boron trifluoride, a Lewis acid by virtue of the boron atom having an incomplete octet of electrons. In forming the adduct, the boron atom attains an octet configuration.
IUCr have proposed a symbol which is shown as a superscript in square brackets in the chemical formula. For example, CaF 2 would be Ca [8cb] F 2 [4t], where [8cb] means cubic coordination and [4t] means tetrahedral. The equivalent symbols in IUPAC are CU−8 and T−4 respectively. [1]
Coordination numbers of 8 to 12 are commonly observed for f-block elements. For example, with bidentate nitrate ions as ligands, Ce IV and Th IV form the 12-coordinate ions [Ce(NO 3) 6] 2− (ceric ammonium nitrate) and [Th(NO 3) 6] 2−. When the surrounding ligands are much smaller than the central atom, even higher coordination numbers may ...
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 ...