Kristallines Tl 2 B 9 H 9 C 2 Me 2 : Synthese und Festkörperstruktur; ein Beitrag zum Problem “attraktive Tl(I)–Tl(I)‐Wechselwirkungen”

Crystalline Tl 2 B 2 H 9 C 2 Me 2 : Synthesis and Solid State Structure; a Contribution to the Problem of Tl(I)–Tl(i) Interactions Crystalline Tl 2 B 9 H 9 C 2 Me 2 ( 1 ) is obtained in the reaction of the carborane B 9 H 11 C 2 Me 2 with two equivalents of thallium(I) ethanolate. An X‐ray diffraction study of 1 shows – contrary to the expectation – the presence of isolated thallium ions and thalladicarbollide counteranions. The latter represent ion pairs composed of Tl(I) + and B 9 H 9 C 2 Me 2 12− units forming slipped icosahedrons. All possible Tl–Tl distances in 1 are too long for even weak attractive interactions, with one exception: A set of symmetry‐equivalent cations possesses a Tl–Tl distances of 3.67 A, which is in a range postulated by calculations for weak bonding.