Copper(ii) tetrafluoroborate complexes with the N³,N⁴-bridging coordination of 1-(tert-butyl)-1H-tetrazole: synthesis, crystal structure and magnetic properties

Abstract

1-(tert-Butyl)-1H-tetrazole (L) reacts with copper(ii) tetrafluoroborate hexahydrate to give the complexes [Cu2L8(H2O)2](BF4)4 (1) or [Cu3L6(H2O)6](BF4)6 (2) depending on the reaction conditions. These complexes, as well as compound L, were characterized using single crystal X-ray analysis. Complex 1 was found to comprise a dinuclear complex cation [Cu2L8(H2O)2](4+) (the Ci symmetry point group), with six tetrazole ligands L showing monodentate N(4)-coordination, and two ligands L providing two tetrazole ring N(3),N(4) bridges between the copper(ii) cations; water molecules complete the distorted octahedral coordination of the metal ions. Complex 2 includes a linear trinuclear complex cation [Cu3L6(H2O)6](6+) (the S6 symmetry point group), in which neighbouring copper(ii) cations are linked by three ligands L via tetrazole ring N(3),N(4) bridges; central and terminal metal ions show octahedral CuN6 and CuN3O3 coordination cores, respectively. The temperature-dependent magnetic susceptibility measurements of complex 2 revealed that the copper(ii) ions were weakly ferromagnetically coupled showing a coupling constant J of 2.2 cm(-1) {H = -2J(S1S2 + S2S3)}. The quantum-chemical investigation of the electronic structure and basicity of ligand L was carried out.

The first organocopper tetrazole derivative: synthesis and characterization

“…30 Regarding 1-alkyltetrazoles, we recently reported the complexation of 1-tert-butyltetrazole with copper(II) tetrafluoroborate in the presence of triethylamine. 24 In this case, deprotonation of the tetrazole ring was not observed, but rare N3,N4-bidentate coordination of the 1-monosubstituted tetrazole was found to occur in the complex that was obtained. In the present work, the use of the potentially chelating ligand HL resulted in deprotometallation of the C5-position of the tetrazole ring.…”

“…In continuation of our earlier synthetic and structural investigations of Cu II complexes with tetrazole ligands, [23][24][25][26] in the present work we aimed to design a ligand containing a tetrazolyl moiety that was capable of direct metallation with a copper salt. 1-(5-Amino-3-azapentyl)tetrazole, which has two amino groups that are potentially capable of achieving chelating coordination near the endocyclic carbon atom, was chosen for this purpose.…”

Halido‐bridged Copper(II) Complexes with 1‐tert‐Butyl‐1H‐tetrazole: Crystal Structure and Magnetic Properties

“…1‐ tert ‐Butyl‐1 H ‐tetrazole was synthesized by heterocyclization of tert ‐butylamine, triethyl orthoformate, and sodium azide according to a previously published procedure (Scheme ) …”

“…It should be noted that this ligand shows a distinctive coordination behavior in comparison with other 1‐alkyltetrazoles. In particular, it can realize rare N 3 ,N 4 ‐bridging mode, which is explained by strong donor properties of tertiary alkyl substituent increasing the donor ability of the heteroring . Moreover, the bulkiness of this substituent influences the crystal structure of complexes formed.…”

Síntesis de tetrazoles 1-sustituídos como precursores de MOFs

“…Esto, sin embargo, es aplicable únicamente para los tetrazoles 5-sustituídos ya que cuentan con un protón lábil, y al perderlo, pueden adoptar los modos de coordinación mencionados con anterioridad.Los tetrazoles 1-sustituídos generalmente exhiben un modo de coordinación monodentado a través del átomo N-423 debido a que este átomo del heterociclo es el más básico, lo que ocasiona que estos compuestos se comporten como bases débiles,24 a diferencia de sus análogos 5-sustituidos que se comportan como ácidos débiles. Sin embargo, existen algunos ejemplos de compuestos de coordinación con tetrazoles 1-sustituídos donde se muestran modos de coordinación bidentados a través de interacciones débiles en los átomos N-3 y N-4, y N-2 y N-3, por lo que pueden distinguirse tres modos de coordinación para este tipo de compuestos (Figura 8) 24. …”