Silver ( I ) Complexes with 1 ’-( Diphenylphosphino )-1-cyanoferrocene : The Art of Improvisation in Coordination

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Synthesis of [Ag(µ 3 -SCN-S,S,N)(1-κP)] 4 (7).
A mixture of ligand 1 (20 mg, 51 µmol) and AgSCN (8.5 mg, 51 µmol) in CDCl 3 (2 mL) was stirred for 20 h. The resulting turbid reaction mixture was filtered and evaporated to afford an orange residue, which was immediately dissolved in ethyl acetate (3 mL). Layering with hexane (9 mL) and crystallization by liquidphase diffusion gave 7 as orange crystalline solid. Yield: 22 mg (78%). 1   Reactions of 1 with AgF. Silver(I) fluoride weighed on a glass cullet was dropped into a solution of ligand 1 in dry ethyl acetate (2 mL) and the resulting mixture was stirred for 24 h, whereupon the solid halide dissolved. Subsequent filtration, layering with hexane (10 mL) and crystallization by liquid phase diffusion afforded orange crystals, which were subjected to X-ray diffraction analysis. The product of the reaction performed at the 1:1 silver-to-1 molar ratio (6.5 mg of AgF and 20 mg of 1) was identified as a co-crystal consisted of [Ag(μ-HF 2 )(1-κP) 2 ] 2 (9) and dimer 3. Unfortunately, poor quality of the available data and disorder S-6 precluded any further refinement. The analogous reaction at the 1:2 AgF-to-1 molar ratio (3.2 mg of AgF and 20 mg of 1) afforded a tiny amount (very few crystals) of compound 10.
Further attempts at obtaining crystalline products by crystallization from different solvents (methanol and acetone) only led to the formation of silver mirror and intractable dark precipitates.
Synthesis of (μ-SiF 6 )[Ag(1-κP) 2 ] 2 (10). Silver(I) hexafluorosilicate (4.5 mg, 12.5 µmol) and nitrile 1 (20 mg, 51 µmol) were mixed in CHCl 3 (2 mL) and the resulting mixture was stirred for 2 h. Then, the volume of the reaction mixture was reduced to the half and the residue was filtered through a PTFE syringe filter (0.45 μm). The product was crystallized by addition of acetone (1 mL) and layering with hexane (10 mL) to afford solvate 10⋅½CHCl 3 ⋅½Me 2 CO as orange crystals. Yield: 18 mg (71%). 1  Cooler (Oxford Cryosystems) using graphite-monochromatized MoKα radiation (λ = 0.71073 Å). The data were corrected for absorption by the methods included in the diffractometer software. The structures were solved by the direct methods (SHELXS97 5 ) and refined by fullmatrix least-squares routine based on F 2 (SHELXL97 5 or SHELXL-2014 6 ). Unless noted otherwise, the non-hydrogen atoms were refined with anisotropic displacement parameters while the hydrogens (CH n ) were included in their calculated positions and refined as riding atoms with U iso set to a multiple of U eq of the respective carbon atom. Relevant crystallographic data and structure refinement parameters are given in the Supporting Information, Table S1. Particular details on structure refinement are as follows.
In many cases, the peripheral moieties, typically the C 5 H 4 CN moieties in compounds with Pmonodentate 1, show partial disorder. This apparently reflects molecular mobility increasing from the compact and rigid core to the periphery. Similarly, solvent molecules in crystalline solvates are often disordered, filling structural voids between bulky complex molecules without interacting with them. For instance, the solvent molecule in the structure of 3⋅CH 2 Cl 2 is disordered and was modelled over four positions using SIMU restraints. Similarly, one of the solvating ethyl acetate molecules in the structure of 5⋅3AcOEt was disordered around an S-11 inversion center and could not be properly modelled. Therefore, its contributions to scattering were removed using the SQUEEZE 7 routine in PLATON. 8 In the case of 6, the solvents of crystallization (acetone and hexane) were heavily disordered in the space left between the polymeric chains and were thus treated analogously. Similar applies to the structures of 7 (illdefined chloroform solvate) and 10·½Me 2 CO·½CHCl 3 , in which also one of the uncoordinated cyano group had to be refined over two positions.
The Ag-coordinate ethyl acetate in 13 is disordered, too, and was refined over two positions (70:30). Because of a close proximity of the contributing orientations, the refinement had to be performed with isotropic displacement factors and some geometry restraints (DFIX).