Template synthesis of a macrocycle with a mixed NHC/phosphine donor set

Reaction of cis-[ReCl(NHC)(CO)4] cis-[1] (NHC = NH,NH-substituted saturated cyclic diaminocarbene) with diphosphine (2-F–C6H4)2P–CH2CH2–P(C6H4-2-F)22 yields complex fac-[Re(NHC)(2)(CO)3]Cl fac-[3]Cl. Deprotonation of the NH,NH-NHC ligand in fac-[3]Cl with KOtBu leads to an intramolecular nucleophilic aromatic substitution of one fluorine atom from each –P(C6H4-2-F) group by the NHC ring nitrogen atoms with formation of complex fac-[4]Cl bearing a facially coordinated [11]ane-P2CNHC ligand. Reaction of cis-[MnBr(NHC)(CO)4] cis-[5] (NHC = NH,NH-substituted saturated cyclic diaminocarbene) with diphosphine 2 yields complex [MnBr(NHC)(2)(CO)2] [6] without substitution of the bromo ligand and with the phosphine donors from the bidentate diphosphine occupying one cis and one trans position to the NHC donor.

Graphical abstractComplex [4]Cl bearing an [11]ane-P2CNHC ligand has been prepared in a template synthesis from the complex bearing an NH,NH-substituted NHC ligand and the diphosphine (2-F–C6H4)2P–CH2CH2–P(C6H4-2-F)2 in a facial arrangement.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► We studied the synthesis of [11]ane-P2CNHC macrocycles at the ReI template. ► A diphenylphosphine and an NH,NH–NHC were linked while coordinated to ReI. ► The ligands to be linked together have to be coordinated in a facial arrangement. ► At MnI, the diphosphine and the NHC are coordinated in the meridional geometry.