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Tellurium–Nitrogen π‐Heterocyclic Chemistry – Synthesis, Structure, and Reactivity Toward Halides and Pyridine of 3,4‐Dicyano‐1,2,5‐telluradiazole
Author(s) -
Semenov Nikolay A.,
Pushkarevsky Nikolay A.,
Beckmann Jens,
Finke Pamela,
Lork Enno,
Mews Rüdiger,
Bagryanskaya Irina Yu.,
Gatilov Yuri V.,
Konchenko Sergey N.,
Vasiliev Vladimir G.,
Zibarev Andrey V.
Publication year - 2012
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201200376
Subject(s) - chemistry , natural bond orbital , pyridine , homo/lumo , molecular orbital , crystallography , adduct , bromide , antibonding molecular orbital , atoms in molecules , supramolecular chemistry , molecule , crystal structure , medicinal chemistry , inorganic chemistry , organic chemistry , atomic orbital , physics , quantum mechanics , electron
The reaction of 2,3‐diaminomaleonitrile with TeX 4 (X = Cl, Br) in the presence of pyridine (Py) and/or triethylamine (Et 3 N) provided 3,4‐dicyano‐1,2,5‐telluradiazole ( 1 ), which was isolated neat and as stable adducts with pyridine, chloride, and bromide, namely, 1· 2Py, (PyH)( 1· Cl), (PyH) 2 ( 1· 2Cl), (Et 3 NH)( 1· Cl), (PyH)( 1· Br), and (PyH) 2 ( 1· 2Br). The molecular and supramolecular structures of these compounds were investigated by X‐ray crystallography. In the solid state, intermolecular associations through secondary Te ··· N interactions as well as N–H ··· X and N–H ··· N hydrogen bonding (X = Cl, Br) were observed. For (PyH)( 1· Br), two polymorphs were found. The bonding situation of 1 and its pyridine and chloride adducts were investigated by MP2 calculations supplemented with the quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analyses. The π symmetry of the frontier molecular orbitals (MOs) of 1 are preserved in the 1· 2Py, ( 1· Cl – ), and ( 1· 2Cl – ) adducts. In the chloride adducts, the highest occupied molecular orbital (HOMO) can be described as an antibonding combination of the HOMO of 1 with the 3p atomic orbitals (AOs) of the chloride ions, whereas the lowest occupied molecular orbital (LUMO) resembles that of the parent 1 . The charge transfer onto the heterocycle in the adducts increases in the order 1· 2Py, ( 1· 2Cl – ), and ( 1· Cl – ). QTAIM analyses of the adducts in the gas phase reveal closed‐shell interactions, whereas NBO analyses indicate negative hyperconjugation as the main formation pathway in these complexes. This description agrees with the Alcock model suggested for secondary bonding interactions between atoms of heavy p‐block elements and atoms with lone pairs.