Nitridorhenium(V) Complexes with 1,3,4‐Triphenyl‐1,2,4‐triazol‐5‐ylidene

Abstract

Abstract[ReNCl2(PPh3)2] and [ReNCl2(PMe2Ph)3] react with the N‐heterocyclic carbene (NHC) 1,3,4‐triphenyl‐1,2,4‐triazol‐5‐ylidene (HLPh) under formation of the stable rhenium(V) nitrido complex [ReNCl(HLPh)(LPh)], which contains one of the two NHC ligands with an additional orthometallation. The rhenium atom in the product is five‐coordinate with a distorted square‐pyramidal coordination sphere. The position trans to the nitrido ligand is blocked by one phenyl ring of the monodentate HLPh ligand. The Re–C(carbene) bond lengths of 2.072(6) and 2.074(6) Å are comparably long and indicate mainly σ‐bonding between the NHC ligand and the electron deficient d2 metal atom.The chloro ligand in [ReNCl(HLPh)(LPh)] is labile and can be replaced by ligands such as pseudohalides or monoanionic thiolates such as diphenyldithiophosphinate (Ph2PS2−) or pyridine‐2‐thiolate (pyS−). X‐ray structure analyses of [ReN(CN)(HLPh)(LPh)] and [ReN(pyS)(HLPh)(LPh)] show that the bonding situation of the NHC ligands (Re–C(carbene) distances between 2.086(3) and 2.130(3) Å) in the product is not significantly influenced by the ligand exchange. The potentially bidentate pyS− ligand is solely coordinated via its thiolato functionality.Hydrogen atoms of each one of the phenyl rings come close to the unoccupied sixth coordination positions of the rhenium atoms in the solid state structures of all complexes. Re–H distances between 2.620 and 2.712Å do not allow to discuss bonding, but with respect to the strong trans labilising influence of “N3−”, weak interactions are indicated.