Synthesis of a TREN in Which the Aryl Substituents are Part of a 45 Atom Macrocycle

A substituted
TREN has been prepared in which the aryl groups in
(ArylNHCH2CH2)3N are substituted
at the 3- and 5-positions with a total of six OCH2(CH2)nCHCH2 groups
(n = 1, 2, 3). Molybdenum nitride complexes, [(ArylNCH2CH2)3N]­Mo­(N), have been isolated as
adducts that contain B­(C6F5)3 bound
to the nitride. Two of these [(ArylNCH2CH2)3N]­Mo­(NB­(C6F5)3) complexes
(n = 1 and 3) were crystallographically characterized.
After removal of the borane from [(ArylNCH2CH2)3N]­Mo­(NB­(C6F5)3) with
PMe3, ring-closing olefin metathesis (RCM) was employed
to join the aryl rings with OCH2(CH2)nCHCH­(CH2)nCH2O links (n = 1–3) between
them. RCM worked best with a W­(O)­(CHCMe3)­(Me2Pyr)­(OHMT)­(PMe2Ph) catalyst (OHMT = hexamethylterphenoxide,
Me2Pyr = 2,5-dimethylpyrrolide) and n =
3. The macrocyclic ligand was removed from the metal through hydrolysis
and isolated in 70–75% yields relative to the borane adducts.
Crystallographic characterization showed that the macrocyclic TREN
ligand in which n = 3 contains three cis double bonds. Hydrogenation produced a TREN in which the three links
are saturated, i.e., O­(CH2)10O.