Preparation of α-diazines and α-2-pyridylazines containing (1R)-(+)-camphor or (1R)-(–)-fenchone residues and their complexes with Group 6 metal carbonyls

Abstract

New 2,3,6,7-tetraaza-1,3,5,7-octatetraene (α-diazine) derivatives camphN–NCH–CHN–Ncamph I, where camph is a (1R)-(+)-camphor residue, C₁₀H₁₆, and fenchN–NCH–CHN–Nfench II, where fench is a 1R-(–)-fenchone residue, C₁₀H₁₆, have been obtained together with the 2′-pyridyl derivatives CamphN–NCHC₅H₄N III and fenchN–NCHC₅H₄N IV. The configurations around the four CN bonds of I or II are E,E,E,E whilst those around the two azine CN bonds in III and IV are E,E. Complexes of the types [M(CO)₄L](M = Cr, Mo or W; L =I–IV), [Mo(CO)₃LL′](L =I, L′= NCMe, PPh₃ or AsPh₃; L =II–IV, L′= PPh₃), [Mo(CO)₂L(PPh₃)₂](L =III or IV) and [Mo(CO)₂Br(η³–CH₂CHCH₂)L](L =I, III or IV) containing these azines as ligands have also been obtained. Complexes of II are the most unstable and these together with tetracarbonyl complexes of IV appear to show restricted rotation around the N–N bond(s) caused by the steric requirements of the methyl groups on the fenchone residue(s). All the complexes have been characterised by multinuclear NMR (¹H, ¹³C and ³¹P), IR and UV/VIS spectroscopies and mass spectrometry. The crystal structures of camphN–NCH–CHN–Ncamph I and fenchN–NCHC₅H₄N IV have been determined.