In chemistry, subhalide usually refers to inorganic compounds that have a low halide:metal ratio, made possible by metal–metal bonding (or element–element bonding for nonmetals), sometimes extensive. Many compounds meet this definition.
The normal halide of boron is BF3. Boron forms many subhalides: several B2X4, including B2F4; also BF. Aluminium forms a variety of subhalides. For gallium, adducts of Ga2Cl4 are known. Phosphorus subhalides include P2I4, P4Cl2, and P7Cl3 (structurally related to P73−). For bismuth, the compound originally described as bismuth monochloride was later shown to consist of Bi95+ clusters and chloride anions. There are many tellurium subhalides, including Te3Cl2, Te2X (X = Cl, Br, I), and two forms of TeI.
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