Mixed complex formation between methyllithium and lithium bromide or iodide in diethyl ether

Abstract

Hence, although some dir donation appears to be necessary for the formation of [Ir(NH3)3NH]1 23 4+ from [Ir(NH3)=,N3]2+, extensive electron transfer leads to loss of nitrene-like properties of the resulting ligand. We propose the name "coordinated nitrene" to describe the NH ligand in [Ir(NH3)6NH]3+ as a means of distinguishing compounds of this type from the formally similar alkyl-and arylimido and nitrido ligands of [Re-{P(CH3)2C6H5j2CI3NR) and [Re{P(CH3)2C6H3}3CI2N] which show very different chemical behavior.Acknowledgment. The authors would like to thank Dr. V. G. Myers, whose doctoral thesis provided the basis for this work, and Mr. T. R. Weaver for useful discussion. The iridium trichloride was generously loaned to us by the Matthey Bishop Co. This research was supported by a National Institutes of Health Predoctoral Research Fellowship to J. W. M. and by a National Science Foundation grant.(41) J. Chatt and B. T. Fteaton, ibid., 705 (1971).

ChemInform Abstract: NMR Spectroscopy of Organolithium Compounds. Part 11. 2H/1H Isotope Shifts for 6Li‐NMR: First Experimental Detection and Applications to Structural Problems in the Field of Organolithium Compounds

“…In addition to the main peaks at 2.18,2.06, 1.33, and 0.22 ppm relative to 0 . 1~ LiBr in THF already described for the 7Li-NMR spectrum [23], we find, aside from some minor lines due to impurities and/or higher aggregated), an additional absorbtion at 0.62 ppm. This signal was not seen in the earlier work, because, as one can infer from the broadened spectrum, the system was still under exchange.…”

“…According to McGarrity and Ogle, aggregates of organolithium compounds easily incorporate hydrolysis products or basic impurities [24]. For the assignment of the various absorptions to individual 'Li environments, we consider first for simplicity without proof tetrameric structures as in the case of methyllithium (see above) with the next neighbour arrangements 2a-d: While Novak and Brown [23] used the intensity changes observed by changing the concentration of LiIwhich by itself provide direct evidence for the formation of mixed aggregates -, we tried first to derive an independent assignment on the basis of the NOE factors obtained from a comparison of the 'H-decoupled and 'H-coupled "Li spectra. The results are given in Table 1.…”

“…The System CH,Li/LiI. The structure of mixed aggregates between organolithium compounds and lithium halides bears on the reactivity of organolithium reagents [22] and was investigated by NMR some years ago by Novak and Brown [23]. These authors measured 38.863-MHz 7Li-and 220-MHz 'H-NMR spectra of mixed complexes between methyllithium and LiI in Et,O and found at -70" low-field from the 7LiI signal three broadened lines which they attributed, on the basis of a tetrameric structure, to the local environment [CH,,CH,CH,] of the aggregate Li,(CHJJ, to the same local environment of Li,(CH,),, and to the local environment [CH,,CH,,I] in the aggregate Li,(CH,),I (from low to high magnetic field).…”

Methode der kontinuierlichen Variation: Verwendung von Job‐Plots zur Untersuchung molekularer Assoziationen in der metallorganischen Chemie

“…Novak und Brown [56] untersuchten 1972 MeLi/LiI-Gemische in Abhängigkeit vom Molenbruch mittels 6 Li-NMR-Spektroskopie. Sie wiesen ein Ensemble von Tetrameren nach (siehe Abbildung 8), gingen aber nicht so weit, einen Abbildung 6.…”

NMR spectroscopy of organolithium compounds. XXVI—The aggregation behaviour of methyllithium in the presence of LiBr and LiI in diethyl ether and tetrahydrofuran

“…3). Since the pioneering work of Waack et al 4 and Novak and Brown, 5 NMR spectroscopy of 1 H, 13 C, 6 Li and 7 Li has played a major role in these type of structural investigations (for a review, see Ref. 6).…”