N-Heterocyclic Phosphorus Compounds Based on N,N '-Disubstituted 9,10-Phenanthrenediimines

The reactivity of N-heterocyclic diphospholenes towards iron triad carbonyls

“…The diphospholene 1 with 2,6-dimethylphenyl (dmp) substituents was found to dissociate with the P-P bond cleavage at 273 K. While diazadiphospholene 2 based on the most sterically hindered phenanthrenediimine shows the ability to dissociate with phosphorus-centered radicals formation at extremely low temperatures (220 K) that was confirmed by EPR spectroscopy. 62 NMR spectra of 2 demonstrate broadened signals even at 220 K. We suggest an increase of steric hindrance of phosphorus atoms on passing from 2,6-dimethylphenyl to the 2,6-di-isopropylphenyl (dipp) substituent results in facilitation of the dissociation process. It is necessary to note that the dissociation of diphospholenes is already known for related species but occurs at rather high temperatures (298-353 K).…”

“…65 Diazadiphospholenes based on 9,10-phenanthrenediimines were prepared according to the literature procedures. 62 Other reactants were purchased commercially and used as received. NMR spectra were recorded by using a Bruker Avance III 400 MHz and Avance Neo 300 instruments with TMS as an internal standard.…”

“…[54][55][56][57][58][59] The interaction of a metal fragment with such reactive compounds is a less studied method for preparing of NHP complexes. 60,61 Recently 2-bromo-(1,3,2)-diazaphospholenes and diazadiphospholenes 62 based on 9,10-phenanthrenediimines 63 has been reported (Scheme 2).…”

Synthetic applications of NHPs: from the hydride pathway to a radical mechanism

“…The exact critical temperature depending on the structure is lower for dimers with bulkier steric groups and longer P-P bonds, as observed in EPR spectroscopy. 17,45,46 In addition, the nuclear magnetic resonance (NMR) spectra can also be used to monitor monomer-dimer equilibria. The solution NMR spectra vary significantly as the temperature increases.…”

“…The exact critical temperature depending on the structure is lower for dimers with bulkier steric groups and longer P–P bonds, as observed in EPR spectroscopy. 17,45,46…”