Structural and spectroscopic properties of rhenium nitrosyl complexes

Olefin Complexes of Low‐Valent Rhenium

“…Contrary to complexes 2a,b the orientation of the C=C bond is perpendicular to the P-Re-P vector, which is indicated by the dihedral angles P (1) (8) Å is comparable to those found in other ethylene rhenium complexes. [21] The Re-N bond length of 1.799(3) Å is in accord with the values found in the literature. [22] The N1-O2 bond separation of 1.208(4) Å is in the range of 1.10 to 1.38 Å expected for a linear NO + type coordination [21][22][23] [Re-N-O angle of 172.7(3)°].…”

“…[21] The Re-N bond length of 1.799(3) Å is in accord with the values found in the literature. [22] The N1-O2 bond separation of 1.208(4) Å is in the range of 1.10 to 1.38 Å expected for a linear NO + type coordination [21][22][23] [Re-N-O angle of 172.7(3)°]. The positions of the hydrogen atoms of the ethylene ligand were located in a difference electron-density map and their coordinates were fixed, but their isotropic displacement parameters were freely refined.…”

Unexpected formation of a new nitrosylrhenium(II) complex from oxorhenium(V)

“…It shows a strong absorption at 1686 cm À1 , which is ascribed to the stretching frequency of the nitrosyl group, and it is considerably lower than that of free NO, which occurs at 1870 cm À1 [3]. This significant lowering is indicative of a net transfer of electron density from Re(II) to the p * orbitals of NO, thereby weakening the NO bond.…”

“…This significant lowering is indicative of a net transfer of electron density from Re(II) to the p * orbitals of NO, thereby weakening the NO bond. The general range for m(NO) in rhenium(II) complexes is 1660-1776 cm À1 [3]. For complexes containing a r/p-donor atom trans to the NO, this frequency lies at the lower end of this range [3].…”

“…Nitrosyl complexes of rhenium have only been obtained in the oxidation states +1 to +3 [3]. The most general method of preparation is the reductive nitrosylation of perrhenate or oxorhenium(V) compounds by gaseous nitric oxide or alkaline hydroxylamine [4,5].…”