Diamino- and Mixed Amino–Amido-N-Heterocyclic Carbenes Based on Triazine Backbones

Abstract

The synthesis of novel hexahydrotriazine-based NHCs from easily available starting materials is described. Tribenzyltriazacyclohexane 1 is converted stepwise to the six-membered diamino carbene 3 with a saturated ring structure. Analogously, the cyclic mixed amino–amido carbene 12 is obtained starting from a cyclic urea derivative. Both carbenes were characterized by trapping reactions with sulfur and selenium as well by the preparation of metal complexes of the type (COD)MX-NHC (M = Rh, Ir; COD = 1,5-cyclooctadiene), which were converted to the respective dicarbonyl complexes (CO)2MX-NHC. IR spectra of the carbonyl derivatives allowed the Tolman electronic parameter to be determined for carbenes 3 (2052 cm–1) and 12 (2058 cm–1) and revealed a shift of 6 cm–1 due to the presence of one amide function. X-ray structure determinations are reported for an amidinium species, a carbene sulfide, and the (COD)RhBr complex of the amino–amido carbene 12.

Determining the Ligand Properties of N‐Heterocyclic Carbenes from 77Se NMR Parameters

“…Sodium bis(trimethylsilyl)amide (2 M in thf; Acros Organics, CAS: 1070‐89‐9), selenium powder (Strem Chemicals, 99.5 %; CAS: 7782‐49‐2), and methyl trifluoromethanesulfonate (Acros Organics, CAS: 333‐27‐7) were purchased and used as received. Compounds 4· Se, 5· Se, 9· Se, 13· Se, 18· Se, 20· Se, 22· Se,9 7· Se,10b 11· Se,17c 15· Se,17e 17· Se, and 19· Se17g are known in the literature. N , N′ ‐1,4‐Bis(4‐fluorophenyl)‐1,4‐diaza‐1,3‐butadiene,28 1· HBr, 4· HBr,29 2· HI,30 3· HCl, 5· HCl,31 6· HCl,32 7· HCl,33 10· HPF 6 ,34 11· HBr,17c 13· HBr,35 1,3‐dimesityl‐4‐hydroxyimidazolium chloride,36 16· HClO 4 ,17f 17· HNO 3 , 19· (HOTf) 2 ,17g 18· HCl,17h and 21· HOTf4i were prepared according to the literature.…”

Structural and Thermodynamics Studies on Polyaminophosphonate Ligands for Uranyl Decorporation

“…15 The intermediate compound 3 was synthesized by reaction of 2 with diethylphosphite in 42% yield. 16 N-alkylation reaction of 1 with 3 resulted in the formation of the bis-phosphonated ester 4 (79%) which led to ligand L 4 (52%) after hydrolysis of phosphonate groups using 6M HCl. Interestingly, the hydrolysis also resulted in the partial deprotection of the benzyl groups, with formation of the mono-benzylated ligand L 3 (13%), together with minute amounts (9%) of the bis deprotected ligand analogue.…”

Carbon‐metalated triazines and tetrazines: Synthesis and reactivity

“…precursors 185, and further reaction of the zwitterionic species 186 with cyclooctadienyl-metal chlorides (Scheme 41). [58] COD ligands could be replaced with two CO moieties to give complexes 188. [58] Analogously, 1,3-dimesityl-4,6-dioxo-1,3,5-triazinan-5-ide-2-ylidene iron(II) complex 190 was prepared from triazine 189, potassium hexamethyl disilazide and CpFe(CO) 2 I. N-Alkylation of product 190 with MeOTf gave the respective sulfonate salt 191 as a yellow powder (Scheme 42).…”

“…[58] COD ligands could be replaced with two CO moieties to give complexes 188. [58] Analogously, 1,3-dimesityl-4,6-dioxo-1,3,5-triazinan-5-ide-2-ylidene iron(II) complex 190 was prepared from triazine 189, potassium hexamethyl disilazide and CpFe(CO) 2 I. N-Alkylation of product 190 with MeOTf gave the respective sulfonate salt 191 as a yellow powder (Scheme 42). [59] Di-tert-butyl gallium(III) monochloride caused the destruction of the 1,3,5-triazacyclohexane nucleus in compound 169 (see Section 3.1.3).…”