Reactions of Imidazolio‐Phosphides with Organotin Chlorides: Surprisingly Diverse

• Published in: European journal of inorganic chemistry 2022-03, Vol.2022 (8), p.n/a
• Main Authors: Goerigk, Florian, Birchall, Nicholas, Feil, Christoph M., Nieger, Martin, Gudat, Dietrich
• Format: Article
• Language: English
• Subjects: Adducts; Chlorides; Dehydrochlorination; Donor-acceptor systems; Inorganic chemistry; Nucleophiles; Phosphides; Phosphines; Reaction mechanisms; Substituent effects; Tin
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.202101026

Reactions of primary imidazolio‐phosphides (“imidazolylidene‐phosphinidenes”) with R2SnCl2 yield as main products spectroscopically detectable Lewis pairs which undergo base‐induced dehydrochlorination in the presence of excess dichlorostannane to afford zwitterionic chloride adducts of distannylated imidazolio‐phosphines. In contrast, reactions with R3SnCl proceed under dismutation to furnish mixtures containing imidazolium salts and stannylated (oligo)phosphines P(SnR3)3 and P7(SnR3)3, respectively. DFT studies were used to rationalize the divergent behavior based on the presumption that the reactions proceed under thermodynamic control and the products observed represent the most stable species under the specific reaction conditions. Computational simulation of selected reaction steps provides a model mechanism for Lewis‐acid promoted creation of PP‐bonds, which is a prerequisite for oligophosphine formation. The computational studies further highlight parallels between reactions of imidazolio‐phosphides with Lewis and Brønsted acids, and allow also to extrapolate the behavior of the P‐nucleophiles towards other electrophiles than organotin chlorides. Reactions of imidazolio‐phosphides (“imidazolylidene‐phosphinidenes”) with organotin mono‐ and dihalides follow different reaction channels. DFT studies reveal that the structurally different products observed represent the most stable species under the specific reaction conditions and indicate that the switch between different reaction modes is controlled by the Lewis acidity of the electrophile employed.