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The most common oxidation states for arsenic are: −3 in the arsenides, which are alloy-like intermetallic compounds, +3 in the arsenites, and +5 in the arsenates and most organoarsenic compounds. Arsenic also bonds readily to itself as seen in the square As 3− 4 ions in the mineral skutterudite. [1]
The arsenate is an ion with the chemical formula AsO 3− 4. [1] Bonding in arsenate consists of a central arsenic atom, with oxidation state +5, double bonded to one oxygen atom and single bonded to a further three oxygen atoms. [2] The four oxygen atoms orient around the arsenic atom in a tetrahedral geometry. [2]
Arsenic also bonds readily to itself as seen in the square As 3− 4 ions in the mineral skutterudite. [33] In the +3 oxidation state , arsenic is typically pyramidal owing to the influence of the lone pair of electrons .
Arsenic (III) binding sites usually use thiol groups of cysteine residues. The catalysis involves thiolates of Cys72, Cys174, and Cys224. In an SN2 reaction, the positive charge on the SAM sulfur atom pulls the bonding electron from the carbon of the methyl group, which interacts with the arsenic lone pair to form an As−C bond, leaving SAH. [31]
Cummins' Mo(N(tBu)Ar) 3 catalyst, also known to split the N-N triple bond in dinitrogen, reacts with yellow arsenic to form a terminal arsenic moiety triple-bonded to the metal center - one of only several compounds known to contain a terminal arsenic atom. [15] Complexes with metal-metal multiple bonds also enable mild As 4 activation ...
The two unique forms of potassium arsenite can be attributed to the different number of oxygen atoms. Potassium meta-arsenite (KAsO 2) contains two oxygen atoms one of which is bonded to the arsenic atom via a double bond. Conversely, Potassium ortho-arsenite (K 3 AsO 3) consists of three oxygen atoms all bound to the arsenic atom via single bonds.
Similarly, realgar has arsenic–arsenic bonds, so the arsenic's oxidation state is +II. A corresponding compound for antimony is Sb 2 (C 6 H 5) 4, where the antimony's oxidation state is +II. Phosphorus has the +1 oxidation state in hypophosphorous acid and the +4 oxidation state in hypophosphoric acid.
In all of these the geometry around the As III centers are approximately trigonal, the lone pair on the arsenic atom is stereochemically active. [1] Well known examples of arsenites include sodium meta-arsenite which contains a polymeric linear anion, (AsO − 2) n, and silver ortho-arsenite, Ag 3 AsO 3, which contains the trigonal AsO 3− 3 ...