Syntheses, rearrangements, and structural analyses of unsaturated nitrogen donor ligands derived from diphenyldiazomethane and the chiral rhenium Lewis acid [(η5-C5H5)Re(NO)(PPh3)]+?

Dalton Transactions Pub Date: 2022-04-18 DOI: 10.1039/D2DT00890D

Abstract

Diphenyldiazomethane and a labile chlorobenzene complex of [(η5-C5H5)Re(NO)(PPh3)]+ BF4? react to give the η1 adduct [(η5-C5H5)Re(NO)(PPh3)(NNCPh2)]+ BF4? (73%). When this is conducted in the presence of copper powder, a 3-phenyl-1H-indazole complex derived from carbon–hydrogen bond activation, [(η5-C5H5)Re(NO)(PPh3)([upper bond 1 start]N[double bond, length as m-dash]C(Ph)[lower bond 1 start]C[double bond, length as m-dash]CHCH[double bond, length as m-dash]CHCH[double bond, length as m-dash]C[lower bond 1 end]N[upper bond 1 end]H)]+ BF4?, is obtained (65%). Subsequent reaction with NaOCH3 gives indazolyl complex (η5-C5H5)Re(NO)(PPh3)([upper bond 1 start]N[lower bond 1 start]C[double bond, length as m-dash]CHCH[double bond, length as m-dash]CHCH[double bond, length as m-dash]C[lower bond 1 end]C(Ph)[double bond, length as m-dash]N[upper bond 1 end]) (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.

Graphical abstract: Syntheses, rearrangements, and structural analyses of unsaturated nitrogen donor ligands derived from diphenyldiazomethane and the chiral rhenium Lewis acid [(η5-C5H5)Re(NO)(PPh3)]+
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