Ligands dinitrogen

Kim et al. have reported that the copper complex bearing the unique dinitrogen ligand (51) catalyzes the aziridination of conjugated as well as nonconjugated olefins with good enantio-selectivity (Scheme 37).159... 

A second, independent spectroscopic proof of the identity of 4 as rans-[Mo(N2)2(weso-prP4) was provided by vibrational spectroscopy. The comparison of the infrared and Raman spectrum (Fig. 7) shows the existence of two N-N vibrations, a symmetric combination at 2044 cm-1 and an antisymmetric combination at 1964 cm-1, indicating the coordination of two dinitrogen ligands. In the presence of a center of inversion the symmetric combination is Raman-allowed and the antisymmetric combination IR allowed. The intensities of vs and vaK as shown in Fig. 2 clearly reflect these selection rules. Moreover, these findings fully agree with results obtained in studies of other Mo(0) bis(dinitrogen)... 

The coordination of the dinitrogen ligand is maintained when traTO-[Re(N2)Cl(dppe)2] is exposed to NaX salts (X = NCS, NCO , Ns ) in THF/MeOH solutions. The isothiocyanato and azido complexes of type (276) have been studied by X-ray structural analysis.A Re— N2 bond length of 1.951 A is observed for the NCS compound which is somewhat shorter than that in the starting material and indicates a considerable degree of double bond character. 

The first study of the energy barriers associated with the migratory insertion reactions occurring in the initiation and propagation steps was carried out with Pd" complexes stabilised by structurally rigid dinitrogen ligands such as bipyridine (bipy), phenanthroline (phen) and bis(arylimino)acenaphthene (Ar-BIAN) [22, 26, 27]. 

The insertions of CO into Pd-Me and of various strained alkenes into Pd-COR supported by the dinitrogen ligand Ar-BIAN have been studied by Vrieze and Elsevier by means of ex situ NMR spectroscopy [22, 51], For example, the sequential insertions of CO and norbomadiene into Pd-alkyl and Pd-acyl bonds allowed the detection and isolation of several intermediates such as acyl(carbonyl) and P-chelate (Scheme 7.24). The Pd complexes isolated after alkene insertion were found to have a structure arising from cis addition of Pd-C(0)R to the exo face of the olefin. 

For attempts to use chiral dinitrogen ligands in these reactions, see G. 

The chromium(O) complex (rans-[Cr(N2)2(dmpe)2] (2) has been prepared together with some incompletely characterized cis isomer from [CrCl2(dmpe)2] according to Scheme 8, which also shows that its reactions all involve displacement of dinitrogen. The trans dinitrogen ligands are linear, and the N—N bond distance (1.122 A) is normal. The IR spectrum of the trans isomer... 

Figures 8E.3-8E.6 show a selection of some ligands that have been successfully used in the palladium-catalyzed AAA reaction. They are classified into four categories 1) chiral phosphines, 2) dinitrogen ligands, 3) P,N-chelate ligands, and 4) mixed chelate ligands. Although this...

The reactions of acyl halides (76) with (rans- M(N2)2(dppe)2] were the first to suggest that a proton could be bound to a dinitrogen ligand. This occurs because of adventitious water, which reacts with acyl halides to generate some hydrohalic acid [Eq. (39)]. 

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