Allenetetramine and Dialkoxydiaminoallene

Abstract

lene and that three ethylene molecules have become bonded to the nickel.

Divalent Carbon(0) Chemistry, Part 2: Protonation and Complexes with Main Group and Transition Metal Lewis Acids

“…Figure 1 also gives experimental values of bond lengths and angles, which are available for 3-BH 3 , [24] 3-CO 2 , [21] and for substituted derivatives of 9-BH 3 [25] and 9-CO 2 . [26] Experimental values have also been reported for the protonated compounds 3-H + , [27] 9-H + [28] and for the diprotonated species 2-(H + ) 2 [29] and 3-(H + ) 2 , [30] as well as for substituted analogues of 7-H + , [31] 8-H + [32] and 8-(H + ) 2 .…”

“…The tetraaminoallene (TAA) 8 reacts with the weak Lewis bases CO 2 and CS 2 to give complexes [(NMe 2 ) 2 C] 2 CÀCX 2 (X = O, S; Scheme 1) in which the central carbon atom of 8 binds to CX 2 by a donor-acceptor bond. [3] Another experimental result which points toward the "hidden" doublelone-pair character of TAAs is the finding that upon protonation the compounds may bind two protons at the central carbon atom rather than at nitrogen, for example, to yield Abstract: Quantum-chemical calculations with DFT (BP86) and ab initio methods (MP2, SCS-MP2) were carried out for protonated and diprotonated compounds N-H + and N-(H + ) 2 and for the complexes N-BH 3 , N-(BH 3 ) 2 , N-CO 2 , N-(CO 2 ) 2 , N-W(CO) 5 , N-Ni(CO) 3 and N-Ni(CO) 2 where N = CA C H T U N G T R E N N U N G (PH 3 ) 2 …”

“…Here we report on quantum chemical calculations using DFT (BP86) and ab initio methods (MP2, SCS-MP2) of the first and second protonation energies of 1-9. We also calculated donor-acceptor complexes of 1-9 with the Lewis acids BH 3 , CO 2 , W(CO) 5 , Ni(CO) 3 , and Ni(CO) 2 . The complexes with N-heterocyclic carbene (NHC) 9 were analyzed to investigate the differences between a divalent carbon(II) and a divalent carbon(0) compound in the donor-acceptor complexes.…”

Distinguishing Carbones from Allenes by Complexation to AuCl

“…With regard to allene complexes, an experimental study by Viehe et al [27] that was published in 1973 reported that tetraaminoallenes (NR 2 ) 2 C=C=CA C H T U N G T R E N N U N G (NR 2 ) 2 strongly bind CO 2 through the central carbon atom as adduct [{(NR 2 ) 2 C} 2 CÀ CO 2 ]. The finding resembles the complex [(PPh 3 ) 2 CÀCO 2 ], which was recently isolated and characterized by X-ray structural analysis.…”

Carbodiylides C(ECp*)2 (E=B–Tl): Another Class of Theoretically Predicted Divalent Carbon(0) Compounds

“…[16] The very strong nucleophilicity of the central carbon atom of the TAAs also comes to the fore by the observation that they easily react with CO 2 , yielding stable donor-acceptor complexes, which feature a [(R 2 N) 2 C] 2 C!CO 2 donor-acceptor bond. [17] It was suggested that the (quasi)linear TAAs should be considered as "hidden" divalent carbon(0) compounds because of their aptitude to serve as double Lewis base in chemical reactions.…”