The Electrostatic Nature of Aryl−Bromine−Halide Synthons:  The Role of Aryl−Bromine−Halide Synthons in the Crystal Structures of the trans-Bis(2-bromopyridine)dihalocopper(II) and trans-Bis(3-bromopyridine)dihalocopper(II) Complexes

Abstract

The role of C-Br‚‚‚X synthons in the structures of Cu(nbp) 2 X 2 (nbp ) n-bromopyridine; n ) 2 and 3) are investigated. A comparison of the role of these synthons in these and in the previously published (nBP) 2 CuX 4 and (nBP)X structures (nBP ) n-bromopyridinium cations; X ) Bror Cl -; n ) 2, 3, or 4) indicate that electrostatic effects, the positive charge on the bromopyridinium cation and the negative charge on the halide anion, play a major role in the strength and directionality of C-Br‚‚‚X synthons. The data indicates that the C-Br‚‚‚X synthons are stronger in the (nBP) 2 CuX 4 and (nBP)X salts compared with the Cu(nbp) 2 X 2 compounds. The supramolecular assembly of these Cu(nbp) 2 X 2 complexes is dominated by nontraditional C-Br‚‚‚X synthons and Cu‚‚‚X semicoordinate bonds. The bromine-halide distances are almost equal to the sum of their van der Waals radii (r vdW ) in Cu(3bp) 2 X 2 but less than the sum of the r vdW by ∼0.24 Å in Cu(2bp) 2 X 2 . The C-Br‚‚‚X angles are close to linear, ranging from 158.15(8)°to 167.90(8)°for Cu(3bp) 2 Cl 2 and Cu(2bp) 2 Cl 2 respectively. The Cu(2bp) 2 X 2 units form chain structures based on the C-Br‚‚‚X synthons. These chains interact via C-H‚‚‚X and π-π stacking to form the three-dimensional structure. In contrast, the chain structures in Cu(3bp) 2 X 2 compounds are based on the Cu‚‚‚X semicoordinate bond. These chains interact via C-Br‚‚‚X synthons to form the three-dimensional structure.

Crystal structure of hydrogen methyl ether perchlorate — 1,3-bis(4- pyridyl)propane (1:1), [C2H7O][ClO4] ·C13H14N2

“…Ar easonable synthetic approach to build such materials through careful selection of organic molecules containing functional groups which self-assemble in the solid state as well as well-known molecular synthons (usually based on intermolecular hydrogen bonds), makes it possible to predict some supramolecular motifs such as tapes, sheets or even three-dimensional networks [4][5][6]. In this regard, N,N'-donor spacer ligands such as 1,2-bis(4-pyridyl)ethane (bpa) and 1,3-bis(4-pyridyl)propane (bpp) are used in both branches of crystal engineering since, apart from its rod-like characteristics, the gauche and anti conformations which may induce supramolecular isomerism in coordination compounds.…”

“…In this regard, N,N'-donor spacer ligands such as 1,2-bis(4-pyridyl)ethane (bpa) and 1,3-bis(4-pyridyl)propane (bpp) are used in both branches of crystal engineering since, apart from its rod-like characteristics, the gauche and anti conformations which may induce supramolecular isomerism in coordination compounds. With this ligand, a large number of novel networks of ingenious design have been constructed [4][5][6][7][8][9]. In particularly, there has been much interest in the rational design and synthesis of cocrystals assemblied with bpa or bpp component [7][8][9].…”

Organizing Radical Species in the Solid State with Halogen Bonding

“…10). Magnetic data for [CuBr 2 (2-Br-py) 2 ] show an absence of any interactions, with perfect Curie-type behavior [46].…”

“…On the other hand, the analogous 2,5-dibromopyridine derivatives, formulated as [CuCl 2 (2,5-Br 2 -py) 2 ] and [CuBr 2 (2,5-Br 2 -py) 2 ], are not isostructural and exhibit antiferro-or ferromagnetic interactions, respectively [46,47]. The antiferromagnetic interactions in the copper chloride salt have been attributed, in spite of a relative long ClÁ Á ÁCl distance (4.16 Å), to this two-halide exchange pathway, in accordance with a non-negligible spin density on the chloride ions (0.109).…”

The role of charge assisted arylhalogen–halide ion interactions in the structures of the dibromopyridinium halide salts

“…Our interest, as well as others, has focused on the role of charge assisted halogen-halide ion interactions in halopyridinium salts of halometallate ions, as well as their physical nature [17][18][19][20][21][22][23][24][25][26][27]. The charge assisted interaction is defined as the halogen bond between halide anion and halogen atom attached to positively charge species.…”