Bis(μ-5-diisopropylamino-1,2,3,4-tetrazolido-κ2 N 2:N 3)bis[(triisopropylphosphane)copper(I)]

In the binuclear centrosymmetric crystal structure of the title compound, [Cu2(C7H14N5)2(C9H21P)2], all atoms except those of the isopropyl groups are approximately co-planar. The Cu(II) atom is in a distorted trigonal–planar CuN2P coordination. Bond angles around the amino N atom suggest sp 2 hybridization. Several intramolecular C—H⋯N interactions are present involving tetrazolate N atoms.

In the binuclear centrosymmetric crystal structure of the title compound, [Cu 2 (C 7 H 14 N 5 ) 2 (C 9 H 21 P) 2 ], all atoms except those of the isopropyl groups are approximately co-planar. The Cu(II) atom is in a distorted trigonal-planar CuN 2 P coordination. Bond angles around the amino N atom suggest sp 2 hybridization. Several intramolecular C-HÁ Á ÁN interactions are present involving tetrazolate N atoms.
Since complexes containing N 5 ligands may be at the edge of isolability due to facile loss of dinitrogen, it is important to develop a knowledge base that allows the synthesis of soluble, tractable 1,2,4-triazolato and tetrazolato complexes. Presumably, the basic coordination chemistry of pentazolato ligands will share similarities with that of tetrazolato ligands.
The present work demonstrates the stabilization of copper tetrazolate complexes using a 2-electron donor phosphane ligand. The copper complex crystallizes as a dimer having all nuclei except the isopropyl groups' in the same plane. The phosphane ligands are terminal, while each tetrazolate ligand bridges two Cu(I) centers.
While the work aimed for a monomeric complex, it can be concluded that the combination of isopropyl groups in the phosphane ligand and the tetrazolate ligand does not provide the necessary steric repulsion. However, enough steric hindrance is provided for the tetrazolate to coordinate in an N2-N3 bridging mode as opposed to the normally observed N1-N2 bridging mode.
The C1-N5-C5 angle of 120.30 (13)° and the C2-N5-C5 angle of 118.89 (13)° suggest that the N-atom of the amino group is sp 2 -hybridized, having its electrons donated to the aromatic ring, thus providing stability to the electron-deficient heterocycle.
Several intramolecular CH-N interactions exist between the tetrazolate's N1 and N4, and the hydrogen atoms on C9, C10, C13, C16. The CH-N distances range from 2.64 to 2.77 Å, whereas the sum of the van der Waals radii for N and H is about 2.7-3.0 Å (Bondi 1964, Allinger et al. 1968), which supports weak, attractive CH-N interactions. These types of supplementary materials sup-2 interactions have been previously observed, where calculations have shown that these interactions provide stability to the heterocycle (Kobrsi et al. 2005, Kobrsi et al. 2006.