Carbonium Ions

Extended Hückel Theory. IV. Carbonium Ions

The Role of Carbonium Ions in Color Reception

It is a fundamental property of conjugated systems to accept a proton or Lewis acid and form a stable carbonium ion. Polyenes that are protonated or add Lewis acids in this manner undergo substantial red shifts. For example, vitamin A(1) acetate absorbs at 350 mmicro in neutral and at 650 mmicro in acidic benzene solution. The fundamental basis for absorption of polyene systems was described in...

Identification of Carbonium and Carbenium Ions by QTAIM

A ferramenta de Gassman-Fentiman da demanda crescente de elétrons foi usada para identificar íons carbênios e íons carbônios. Contudo, devido ao seu entendimento ambíguo, ela foi pivô de uma disputa histórica. Nós aplicamos a metodologia da Teoria Quântica de Átomos em Moléculas QTAIM para caracterizar íons carbênios e íons carbônios de uma forma mais eficaz e mais fácil. Essa metodologia pode ...

Carbenium and carbonium ions in liquid- and solid-superacid-catalyzed activation of small alkanes*

Acid-catalyzed hydrocarbon reactions involve by far the largest amount of catalyst and the largest volume of transformation in oil refinery and chemical industry. However, despite the general agreement on the carbocationic nature of the reaction intermediates, the initial steps and the true nature of the cations on the surface are still open to debate. On these points our basic knowledge has ga...

Stabilised Carbonium Ions in the Organic Chemistry of Platinum THE EVIDENCE FOR THEIR EXISTENCE

Historically, platinum has played a prominent role in organometallic chemistry. The compounds KPtCI,(C,H,)H,O (I), PtMe, (X) (2) and Chugaev's salt [PtC,H,,N,],Clx (3, 4) present some of the fist examples of stable metal-olefin, metal-alkyl and metalcarbene complexes, although ironically the nature of the bonding in these compounds was not immediately recognised. In the study of organometallic ...