Syntheses, rearrangements, and structural analyses of unsaturated nitrogen donor ligands derived from diphenyldiazomethane and the chiral rhenium Lewis acid [(η 5 -C 5 H 5 )Re(NO)(PPh 3 )] .

Diphenyldiazomethane and a labile chlorobenzene complex of [(η 5 -C 5 H 5 )Re(NO)(PPh 3 )] + BF 4 - react to give the η 1 adduct [(η 5 -C 5 H 5 )Re(NO)(PPh 3 )(NNCPh 2 )] + BF 4 - (73%). When this is conducted in the presence of copper powder, a 3-phenyl-1 H -indazole complex derived from carbon-hydrogen bond activation, [(η 5 -C 5 H 5 )Re(NO)(PPh 3 )(NC(Ph)CCHCHCHCHCNH)] + BF 4 - , is obtained (65%). Subsequent reaction with NaOCH 3 gives indazolyl complex (η 5 -C 5 H 5 )Re(NO)(PPh 3 )(NCCHCHCHCHCC(Ph)N) (85%), derived from NH deprotonation and a 1,2-rhenium shift. Crystal structures of the three new complexes are determined. DFT calculations are used to probe the mechanism of the 1,2-shift and energetics of alternative Re-N rotamers and linkage isomers, and assign bond orders and dominant resonance formulations.