Silver–iodocarbon complexes: crystal structures of eight compounds obtained from the reactions of AgPF6or AgNO3with CH2I2, I(CH2)3I and simple aryl iodides

Abstract

Eight silver(I)–iodocarbon complexes have been prepared and structurally characterized by single-crystal X-ray diffraction. In [Ag{I(CH2)3I}2]PF6, [Ag(ICH2I)2]PF6, [Ag(1,2-I2C6H4)3]PF6 and [Ag(1,2-BrIC6H4)4]PF6 the silver ions are four-co-ordinate and bonded to four iodine atoms of four iodocarbon ligands, the co-ordination geometry varying from slightly distorted tetrahedral to trigonal pyramidal. Typical Ag–I bond lengths are in the range 2.8–2.9 Å though the axial Ag–I bond in [Ag(1,2-I2C6H4)3]PF6 is significantly elongated to 3.2–3.3 Å. The diiodocarbons function as bridging ligands in [Ag{I(CH2)3I}2]PF6 and [Ag(ICH2I)2]PF6. The structure of the former consists of a chain polymer built from Ag[I(CH2)3I]2Ag rings whilst the latter consists of (AgICH2I)n chains cross-linked by Ag(ICH2I)2Ag rings. The compound [Ag(1,2-I2C6H4)3]PF6 is a tetrameric cyclic structure in which one-third of the 1,2-I2C6H4 ligands bridge two silvers via the two iodine atoms, the others functioning as monodentate to a silver atom via one of the iodine atoms. The compound [Ag2(O2PF2)2(p-IC6H4Me)] contains a complex sheet Ag(O2PF2)n structure in which an iodotoluene bridges two silvers via an iodo and an η2-arene linkage. Each difluorophosphate links four silvers via two µ-oxygen bridges. The compound [Ag(O2PF2)(1,4-I2C6H4)] contains [Ag(O2PF2)]n chains in which the difluorophosphate forms a three-atom O,O′ bridge. These chains are cross-linked via bridging 1,4-I2C6H4 ligands which co-ordinate to silver via the iodine atoms. The compound [Ag(NO3)(CH2I2)] is a sheet array derived from fused Ag4(µ-NO3)2(µ-ICH2I)2 16-atom rings with each silver bonded to two oxygen and two iodine atoms in a distorted-tetrahedral array. The compound [Ag(NO3)(1,2-I2C6H4)] is composed of spiral chains of [Ag(µ-NO3)]n in which the nitrate uses only one oxygen atom to bridge two silvers. Each silver is bonded to two iodine and two oxygen atoms. The ‘AgI2O2’ bond angles range from 82 to 134°. The 1,2-I2C6H4 ligands bridge alternate first and third silvers along the chain and stack on either side of the [Ag(NO3)]n chain to produce two complementary spiral arrays.