Reactions of pyridyl donors with halogens and interhalogens: an X-ray diffraction and FT-Raman investigation

A Unique Case of Oxidative Addition of Interhalogens IX (X=Cl, Br) to Organodiselone Ligands: Nature of the Chemical Bonding in Asymmetric ISeX Polarised Hypervalent Systems

“…A band at 251 cm À1 is also present in the FT-Raman spectrum of compound VII, but this is dominated by a peak at 177 cm À1 due to the stretching of the slightly perturbed diiodine molecule. [26] The assignment of the band at 267 cm À1 in the case of VI and at 251 cm À1 in the case of VII is consistent with those previously reported for [28] In the FT-Raman spectrum of compound V, therefore, the peaks at 275 (very intense), 218 and 106 cm À1 can be respectively attributed to the s g and s u stretchings and the p u bending vibration modes of the Cl À Se À Cl frameworks. However, three other peaks, at 182, 131 and 75 cm À1 , are clearly visible in this spectrum, with the first being more intense than the second (see the Supporting Information).…”

“…[14b, 23b, 26,27] In fact, as already observed for selenium hypervalent Br 2 adducts, the FT-Raman spectrum of a symmetrical BrÀSeÀBr group shows only a single peak near 160 cm [28] Similar considerations can be applied to the vibrational properties of an I À Se À Br group, which should resemble those of an [I À Br À Br] À anion, for which normal mode stretching frequencies have been calculated at 131 and 174 cm À1 (I À Se À Br and [I À Br À Br] À threebody systems can both be described within the same MO bonding scheme (3c-4e) and show similarities in mass). Unfortunately, in I, II and III (the only example of a pure selenium hypervalent IBr adduct so far reported), [17] the SeÀBr distances are profoundly affected by an intramolecular hydrogen bond (see Figure 1 and Unfortunately, no vibrational spectroscopic data are available in the literature for chalcogen-hypervalent Cl 2 adducts and, therefore, no structural/vibrational comparison of the ClÀEÀCl (E = S, Se) framework with the anions [ClÀXÀCl] À (X = I, Br) has been possible so far.…”

Structures, Vibrational Frequencies, and Stabilities of Halogen Cluster Anions and Cations, Xn+/–, n = 3, 4, and 5

“…The structure and vibrational frequencies of Cl 3 + have been predicted with molecular structure optimizations at the DFT, 32,74 MP2, 71,74 and CCSD(T) 32 anions have been correlated with the experimental data. 67,68,70,77,80 A DFT level study of the molecular structure and vibrational frequencies of the Cl 4 + cation have been compared with experiment, 60 and SCF and DFT computations have been reported for the Br 4 + cation. 77,78 The electronic structures and energies of various rotamers of Cl 5 + were predicted at the SCF level with a minimal basis set.…”

2,5-Bis(pyridinium-2-yl)-3,6-bis(2-pyridyl)pyrazine bis[tetrachloridoaurate(III)]

“…Recently, we reported the synthesis and crystal structures of two proton-transfer complexes (Abedi et al, 2008;Kalateh et al, 2008). Several proton-transfer systems using 2,3,5,6-tetrakis (2 (Padgett et al, 2005) (Aragoni et al, 2005a) (Aragoni et al, 2005b) (Graf & Stoeckli-Evans, 1996) (Bock et al, 1992), have been synthesized and characterized by single-crystal X-ray diffraction methods. Several proton-transfer systems using AuCl 4 as proton acceptor molecules, such as [EMI] (Hasan et al, 1999) (Zhang et al, 2006) (Yap et al, 1995) (Yıldırım et al, 2009a) and [pz(py) 2 H][AuCl 4 ], (XX), (Yıldırım et al, 2009b) (EMI is 1ethyl-3-methylimidazolium, BMI is 1-butyl-3-methylimidazolium, H 2 bipy is 2,2′-bipyridinium, DPpyH is 2,6-diphenylpyridinium, H 2 DA18C6 is 1,10-diazonia-18-crown-6, Me 2 Ph 2 phenH is 2,9-dimethyl-4,7-diphenyl-1,10-phenanthrolin-1ium and pz(py) 2 H is 2-[3-(2-pyridyl)pyrazin-2-yl]pyridinium) have been synthesized and characterized by single-crystal X-ray diffraction methods.…”