A 17 electron chromium complex having both nitrosyl and unidentate nitrito ligands. The crystal and molecular structure of dinitritonitrosyltripyridinechromium monopyridine solvate, (ONO) 2(NO)(C 5H 5N) 3Cr·C 5H 5N [1

Abstract

Irradiation of a solution of Cr(CO) 6 in tetrahydrofuran while purging simultaneously with a stream of nitric oxide gas produces a deep red solution within five minutes. The red solid isolated from the reaction solution eluded purification by standard methods. This solid was dissolved in pyridine and heated to 70 °C. The initial red solution changed to a deep green color from which a green solid was isolated. Extraction of this solid with methylene chloride gave a green solution from which a small amount of a green, solid residue was isolated. This residue crystallized from pyridine solution predominantly as very thin green platelets and several larger red crystals of the tittle compound, which was identified and characterized structurally by X-ray crystallography. Space group Pnna; Z = 4; unit cell dimensions: a = 19.148(4) Å, b = 10.101(2) Å, c = 12.345(3) Å and V = 2388(1) Å 3. The molecule is a six-coordinate complex of symmetry C 2 having three pyridine ligands in a meridional arrangement, with nitrito ligands trans to each other and bonded to the Cr atom through only one oxygen atom. The linear nitrosyl ligand is trans to one of the pyridine ligands. A Crystallographic two-fold axis of rotation passes through the nitrosyl ligand, the Cr atom and the pyridine ligand trans to the nitrosyl ligand. The pyridine solvate molecule lies on another crystallographic two-fold axis and appears to be disordered so that the nitrogen atom is scrambled randomly over all six ring atom positions. This is only the second structurally characterized complex with a unidentate, nitrito ligand. It is also if interest as a 17 electron Cr nitrosyl complex, isoelectronic with the [Cr(CN) 5NO][ 3− ion, with which comparison can be made.