Carbodiphosphorane C(PPh₃)₂as a Single and Twofold Lewis Base with Boranes: Synthesis, Crystal Structures and Theoretical Studies on [H₃B{C(PPh₃)₂}] and [{(μ‐H)H₄B₂}{C(PPh₃)₂}]⁺

Abstract

The donor‐acceptor complex [(H3B){C(PPh3)2}] (2) has been synthesized by treating B2H6 with C(PPh3)2 and its geometry determined by X‐ray structure analysis. Treatment of 2 with DME yields the complex [{(μ‐H)H4B2}{C(PPh3)2}][B2H7] (4), which has also been isolated and structurally characterized. Compound 4 is the first complex of a carbodiphosphorane where the carbon donor atom binds with its two‐electron lone pairs to two main‐group Lewis acids larger than protons. This reaction is likely to occur via initial formation of [(H3B)2{C(PPh3)2}] (6), which subsequently reacts with B2H6, with loss of a hydride, to yield 4. Quantum chemical calculations of 2, 4+ and 6 show that the carbon–boron bonds in these complexes are very strong, and analysis of the bonding situation using the EDA, NBO and AIM methods reveals typical bonding patterns between the divalent carbon(0) moieties and one or two Lewis acids. The carbon donor atom of the carbodiphosphorane moiety remains strongly negatively charged even in the cation 4+. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Distinguishing Carbones from Allenes by Complexation to AuCl

“…However, the occupation of the enforced p lone-pair orbital is much smaller (0.69 e) than in the other compounds. In summary, the NBO analysis of the electronic structure suggests that the bonding situation [8]. Experimental values for 1,…”

“…It has been shown in previous studies that bond strength and bond length often do not correlate with each other. [60] The calculated DE int value of the carbodiphosphorane (CDP) complex 1A C H T U N G T R E N N U N G (AuCl) (À71.2 kcal mol Table 2 shows that the orbital interactions DE orb in 3- [8]. Experimental values for 1(AuCCPhNO 2 ), [25] 5A C H T U N G T R E N N U N G (AuPPh 3 ) + [17a] and 8A C H T U N G T R E N N U N G (AuCl) [56] .…”

“…One difference between divalent [7] carbon(II) and divalent carbon(0) compounds is that carbones have two electron lone pairs, whereas carbenes have only one. Therefore, the former compounds may easily bind two Lewis acids, [8] whereas carbenes should normally bind to only one. Furthermore, carbones possess not only a very high first proton affinity (PA) but also an unusually high second PA, which distinguishes them from carbenes.…”

Formation and Crystal Structures of Lewis Acid Adducts of Ph3PCHP(O)Ph2; New Neutral and Cationic Species

“…As yet, only type C compounds were detected in which the Lewis acid at the carbon atom is H + , thus producing salt like compounds. Solvent reactions with proton abstraction of addition compounds with 1 and other Lewis acids were reported recently [11].…”

Reaction of C(PPh3)2 with MI2 Compounds (M = Zn, Cd) – Formation and Crystal Structures of [I2Zn{C(PPh3)2}], [(I2Cd{C(PPh3)2})2] and the Salt‐Like Compounds (HC{PPh3}2)[MI3(THF)] and (HC{PPh3}2)2[ZnI4]

“…[15] We have recently reported the coordination of 1 to two boron atoms. [16] The coordination chemistry of ylides has been summarized in several reviews. [17,18,19] We have recently isolated the first complex with two molecules of 1 in a linear arrangement in the cationic complex [1ǞAgǟ1] + .…”