A series of thioether and selenoether complexes [MCl 2 (EPh 2 ) 2 ] and [MCl 2 (SMePh) 2 ] (M ) Pt, Pd; E ) S, Se) have been prepared and characterized to explore the isomerism of the complexes in solution and in the solid state. The NMR spectroscopic information indicates that only one isomer is present in solution in case of the palladium complexes, while two isomers are formed in the case of most platinum complexes. Single-crystal X-ray structures of trans- 5t), and trans-[PtCl 2 (SMePh) 2 ] (7t) are reported and have been used as starting points for the X-ray powder diffraction structure determinations using simulated annealing method together with Rietveld refinement of the powder diffraction data. The presence of only trans-isomers in the solid phases was deduced in the case of [PdCl 2 (SPh 2 ) 2 ] and [PdCl 2 (SePh 2 ) 2 ] (1t and 2t, respectively). By contrast, the Rietveld refinement of the powder X-ray diffraction diagrams of [PtCl 2 (SPh 2 ) 2 ] and [PtCl 2 (SePh 2 ) 2 ] indicated the presence of both trans-and cis-isomers (3t, 3c and 4t, 4c, respectively) with mixing ratios that are consistent with NMR spectroscopic information in solution. The density functional theory calculations using [MCl 2 (EMe 2 ) 2 ] as model complexes indicated that while the trans-isomers of the palladium complexes lie at significantly lower energy than the cis-isomers do, in the case of the platinum complexes the energy difference is smaller and decreases, as the chalcogen atom of the chalcogenoether ligand becomes heavier.
The pathways to the formation of the series of [RuCl2(CO)2(ERR')2] (E = S, Se, Te; R, R' = Me, Ph) complexes from [RuCl2(CO)3]2 and ERR' have been explored experimentally in...
The complexes [M(2){mu-N,N'-Se(NR)(2)}(2)](CF(3)SO(3))(2) (1, M = Ag, R = (t)Bu; 2, M = Ag, R = Ad; 3, M = Cu, R = (t)Bu; 4, M = Cu, R = Ad; Ad = 1-adamantyl) were prepared in good yields from the reaction of the corresponding selenium diimide with silver or copper triflate in toluene and were characterized in solution using multinuclear NMR spectroscopy. Recrystallization of 1-4 from a variety of solvents produced 1.2CH(2)Cl(2), 2(AdNH(3))(CF(3)SO(3)) (a few crystals), 3.2thf, and 4.1/2C(7)H(8), which were characterized by X-ray crystallography. All of these salts contain a metallacyclic [M(2){mu-N,N'-Se(NR)(2)}(2)](2+) [M = Ag, Cu; R = (t)Bu, Ad] cation, the frameworks of which exhibit M...M close contacts of 2.7384(9), 2.751(2), 2.556(2)-2.569(2), and 2.531(1) A, respectively. The M...M interaction was further explored by PBE/def-TZVP calculations of the dications [M(2){mu-N,N'-Se(NR)(2)}(2)](2+) (M = Ag, Cu; R = H, Me, (t)Bu, Ad). The geometry optimizations yielded metric parameters that were in good agreement with experimental values, where available. For both metals, it was observed that the M...M distance became shorter, as the organic substituent on nitrogen became bulkier. At the same time, the metallacyclic framework deviated more significantly from planarity. A survey of related dinuclear silver(I) and copper(I) complexes showed that, while there is some correlation between the bite size and the M...M distance, the latter is more dependent on the deviation from planarity of the D(2)M...MD(2) fragment. Atoms in molecules calculations clearly showed the presence of a bond critical point between the two silver or copper centers, as well as two ring critical points. Our computational results are consistent with other recent molecular orbital studies at different levels of theory and indicate the existence of d(10)-d(10) closed-shell metallophilic interactions in 1-4.
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