6533b858fe1ef96bd12b6166

RESEARCH PRODUCT

Self-Assembled One- and Two-Dimensional Networks Based on NH2Me2[ReX5(DMF)] (X = Cl and Br) Species: Polymorphism and Supramolecular Isomerism in Re(IV) Compounds

subject

description

Three mononuclear rhenium(IV) compounds of general formula NH 2 Me 2 [ReX 5 (DMF)] [NH 2 Me 2 + = dimethylammonium cation, DMF = N,N-dimethylformamide, and X = Cl (1 and 2) and Br (3)] have been prepared and characterized. In all three cases, the rhenium atom is six-coordinated by five chloro (1 and 2) or bromo (3) atoms and one oxygen atom from a DMF molecule (1―3) building a somewhat distorted octahedral surrounding. Short Re IV ―X · · · X―Re IV contacts and H-bonds occur in the crystal lattice generating novel supramolecular Re(IV) architectures. 1 and 2 are polymorphs and supramolecular isomers that exhibit supramolecular ladder-like ( 1 ) and rectangular two-dimensional grids (2), the different intermolecular X· · ·X contacts playing a structure-determining role. Noteworthy, the formation of 1 and 2 is selective and dependent on the crystallization conditions. Although compound 3 is isolated using the same crystallization conditions as 2, their crystal packing is different. The investigation of the magnetic behavior of 1―3 in the temperature range 1.9―250 K showed the occurrence of maxima of the magnetic susceptibility at 10.5 (1), 12.0 (2), and 17.0 K (3), which are the signature of significant intermolecular antiferromagnetic interactions. The short Re IV ―X· · · X―Re IV contacts provide the exchange pathway for the overall antiferromagnetic behavior observed in 1―3. The magnetostructural results of 1―3 are compared with those of the related compounds NBu 4 [ReX 5 (DMF)] [NBu 4 + = tetra-n-butylammonium cation with X = Cl (4) and Br (5)] which were reported elsewhere.