Bimetallic complexes with the Ag-Sb bonds: synthesis and structure features

Tri(para-tolyl)antimony reacts with silver nitrate in a methanol/acetonitrile mixture at room temperature in both 3:1 and 4:1 molar ratios to form the ionic complex [(p-Tol3Sb)4Ag][NO3] (1). The reaction product of triphenylantimony with silver nitrate under the same conditions is nitratotris(triphenylstibine)silver (Ph3Sb)3AgNO3 (2), regardless of their molar ratio. An attempt to replace the nitrate ligand in the (Ph3Sb)3AgNO3 complex with a carboxylate ligand under the action of 2-methoxybenzoic acid (molar ratio 1:1) and the addition of triethylamine resulted in the crystallization of the adduct of the composition (Ph3Sb)3AgOC(O)C6H4OMe-2·(Ph3Sb)3AgNO3·2СН3ОН (3) from the reaction mixture with a yield of 84 %. Complexes 1-3 were characterized by IR spectroscopy and X-ray diffraction analysis (XRD). According to XRD data, the Ag and Sb atoms in 1-3 have a tetrahedral coordination distorted to varying degrees with the angles between the bonds deviating from the theoretical value of 109.5°. The average Ag-Sb distances in 1-3 are 2.747, 2.732, 2.726 Å, respectively. The Sb-C bonds vary in the ranges of 2.128(3)-2.145(3) Å (1), 2.127(5)-2.147(5) Å (2), 2.124(6)-2.156(6) Å (3). In ionic compound 1, the nitrate anion is planar and includes the C2 symmetry axis coinciding with one of the N-O bonds; the O-N bonds are 1.148(6) and 2×1.164(4) Å, the bond angles are 110.4(7)° and 2×124.8(4)°. In 2 the Ag-O distance is 2.306(13) Å. In crystal 3 there are two identical fragments of (Ph3Sb)3Ag, in which the OC(O)C6H4OMe-2 and NO3 groups have an occupancy of 50%. The Ag-O distances with the nitrate and carboxylate groups are 2.263(14) and 2.352(18) Å, respectively. Each fragment contains one molecule of solvate methanol.