Template synthesis of tungsten complexes with saturated N-heterocyclic carbene ligands

Abstract

Tungsten complex with a coordinated 2-azidoethyl isocyanide ligand reacts with PMe3 at the azido function to give a complex with a coordinated iminophosphorane which upon hydrolysis of the P=N bond yields a complex with an NH,NH-stabilized N-heterocyclic carbene ligand, 7; alkylation of the carbene ring nitrogen atoms gives a complex with an N,N'-dialkylated imidazolidin-2-ylidene ligand, 8 .

Template‐Controlled Formation of an [11]ane‐P2CNHC Macrocyclic Ligand at an Iron(II) Template

“…[10] Complex [3]PF 6 was not isolated but instead was directly treated with 1 equiv. of 2-azidoethyl isocyanide (4) [11] in dichloromethane to give complex [5] The signal for the isocyanide carbon atom (C-16) in the 13 C{ 1 H} NMR spectrum of [3]PF 6 appears at δ = 164.2 ppm with a 2 J(P,C) coupling constant of 28.0 Hz. All other resonances have been assigned based on 2D NMR spectroscopy.…”

“…Our approach to the template-controlled synthesis of an [11]ane-P 2 C NHC ligand requires the coordination of a suitably substituted diphosphane and a reactive cyclic NH,NHstabilized diaminocarbene in facial positions to the template metal center and their subsequent connection while coordinated. [4,5] A suitable diphosphane is 1,2-bis[bis(2-fluorophenyl)phosphanyl]benzene (2), [4a,8] which reacts with [Fe(η 5 -C 5 H 5 )(η 6 -PhMe)]PF 6 [9] under irradiation in acetonitrile for 6 h to give complex [Fe(η 5 -C 5 H 5 )(2)(CH 3 CN)]PF 6 ([3]PF 6 ) (Scheme 1).…”

“…Iron(II) has been used as template for the generation of P 3 macrocycles (B, Figure 1), which can be liberated from the metal center. [7] Here we describe the template-controlled formation of an [11]ane-P 2 C NHC macrocycle at a {CpFe II } template leading to complex [1]PF 6 .…”

“…The facially coordinated NH,NH-stabilized NHC and the fluorinated diphosphane ligands were linked by N,NЈ-deprotonation of the NHC and nucleophilic attack of the nitrogen atoms at two C-F bonds, which gave -after anion exchange with NH 4 PF 6 -complex [1]PF 6 bearing the macrocyclic [11]ane-P 2 C NHC ligand.…”

“…[1] N-Heterocyclic carbene (NHC) [2] and phosphane ligands [3] are known to form stable metal complexes, and this stability can be further enhanced by incorporation of these donor groups into macrocyclic ligands. We have prepared complexes of type A (Figure 1) bearing the facially coordinated mixed diphosphane-NHC macrocyclic ligand [11]ane-P 2 C NHC in a template synthesis at template centers such as {Re I (CO) 3 }, [4] {Mn I (CO) 3 }, [4] and {CpRu II }. [5] A Figure 1.…”