Spectroscopic and structural studies on 1 : 2 adducts of silver(I) salts with tricyclohexylarsine

摘要

A series of mononuclear complexes [Ag{As(C6H11)(3)}(2)X] (X = Cl, Br, I, CN, NCO, OClO3, O2NO or O2CCF3) have been synthesized and characterised by room temperature single crystal X-ray determinations and low-frequency vibrational spectroscopy. For X = Cl, Pr I or OClO3 the crystal structures are isomorphous with a number of their previously recorded P(C6H11)(3) counterparts, crystallising in the familiar monoclinic C2/c array with the Ag-X bond lying on a crystallographic 2 axis (the perchlorate is disordered) which also relates the pair of As(C6H11)(3) ligands. The silver environment in all is planar three-co-ordinate XAgAs2. For X = CN, NCO or O2NO the derivative lower-symmetry triclinic P (1) over bar array, also common among the P(C6H11), analogues is found. The trifluoroacetate, resembling the nitrate in that the anion behaves as a small 'bite' bidentate ligand, [Ag{As(C6H11)(3)}(2)(O2CCF3)], is monoclinic space group P2(1). The thiocyanate by contrast, utilising the ambidentate capacity of the SCN ligand, remarkably, is a linear polymer, ...{As(C6H11)(3)}(2)Ag(SCN)Ag(SCN)..., triclinic, space group P1, in which the silver atom environment is four-co-ordinate, NSAgAs2. Far-IR spectra of the halide and pseudohalide complexes in the series exhibit single bands due to v(AgX) vibrational modes at 230, 165, 139, 262 and 311 cm(-1) for X = Cl, Pr, I, NCO and CN respectively. These are all higher than the values for the corresponding P(C6H11)3 complexes, suggesting that the Ag-X bonding is stronger in the As(C6H11)(3) complexes, this being the result of weakened Ag-L bonding in going from L = P(C6H11)(3) to As(C6H11)(3). [References: 21]