Carbodiphosphorane C(PPh3)2 as 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}]+

✍ Scribed by Wolfgang Petz; Florian Öxler; Bernhard Neumüller; Ralf Tonner; Gernot Frenking

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 346 KB
• Volume: 2009
• Category: Article
• ISSN: 1434-1948
• DOI: 10.1002/ejic.200900691

✦ Synopsis

Abstract

The donor‐acceptor complex [(H~3~B){C(PPh~3~)~2~}] (2) has been synthesized by treating B~2~H~6~ with C(PPh~3~)~2~ and its geometry determined by X‐ray structure analysis. Treatment of 2 with DME yields the complex [{(μ‐H)H~4~B~2~}{C(PPh~3~)~2~}][B~2~H~7~] (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 [(H~3~B)~2~{C(PPh~3~)~2~}] (6), which subsequently reacts with B~2~H~6~, 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)