The solid-state molecular structure of W(NO)3Cl3 and the nature of its W—NO bonding

Abstract

The monomeric trinitrosyl complex, W(NO)3Cl3, can be prepared by the treatment of WCl6 in CH2Cl2 with NO gas, and its identity has been unambiguously confirmed by a single-crystal X-ray diffraction analysis. The complex crystallizes in the space group Pmn21 as a three-component twin (a = 10.4280(4) Å, b = 6.3289(2) Å, c = 5.6854(2) Å, Z = 2, R1 = 0.065, wR2 = 0.176). Its solid-state molecular structure consists of a tungsten centre bound to three chloride ligands and three linear nitrosyl ligands in a fac-octahedral stereochemistry. In addition, the structure contains a crystallographically imposed mirror plane. The two independent W—N linkages are 1.88(2) and 1.92(1) Å long, while the two corresponding N—O bond lengths are 1.13(2) and 1.16(2) Å. DFT calculations on fac-W(NO)3Cl3 at the B3LYP/LANL2DZ level of theory afford optimized intramolecular metrical parameters that match the X-ray crystallographically determined bond lengths and bond angles quite well. In addition, they provide a rationale for the nearly linear W-N-O linkages extant in the complex. Solutions of fac-W(NO)3Cl3 in CH2Cl2 lose ClNO under ambient conditions and deposit the well-known [W(NO)2Cl2]n polymer, and this conversion is fully reversible.Key words: nitrosyl, tungsten, structure, bonding.