Crystal Structures and ab Initio Calculations of New Dicationic Telluranes (λ⁴-Tellane), [10−Te−4(C2X2)]²⁺ (X = S, Se):  Positively Charged Hypervalent Bonding Systems

Abstract

The reactions of 2,6-bis[(phenylthio- or phenylseleno)methyl]phenyl phenyl telluride or the corresponding Te-oxide, with NOBF4 or trifluoromethanesulfonic anhydride afforded the new telluranes, [10−Te−4(C2X2)]2+·2Y- (λ4-tellane) (X = S or Se, Y = BF4 or CF3SO3). These compounds were characterized by elemental and spectroscopic (FABMS, 1H, 13C, and 125Te NMR) analyses. X-ray structure determinations revealed that the hypervalent tellurium atoms are at the center of a distorted trigonal bipyramid, with two apical sulfonio or selenonio ligands connected via transannular bonds. The Te−S distances are in the range 2.652−2.706 Å, the Te−Se distances in the range 2.759−2.807 Å, and the X−Te−X bond angles in the range 160.41−163.92 °. Ab initio calculations indicate that the positive charges in the dications are exclusively on the three chalcogen atoms that form three-center, four-electron bonds.

Homoleptic Gold Acetonitrile Complexes with Medium to Very Weakly Coordinating Counterions: Effect on Aurophilicity?

“…Nitrosyl salts of WCAs represent very useful oxidants in synthetic chemistry,f or example, for reactive cations, [29] maingroup dications, [30] monocations, [31] and adducts like [P 4 NO] + [32] or [R 2 S 2 NO] + . [32,33] 4 ] À (1d)i np articulara lready provedi ts suitability as astarting materialfor main-group chemistry.…”

Studies on diverse chemical species derived from chalcogen atoms ~ The Footprint of Professor Naomichi Furukawa in Heteroatom Chemistry ~

“…Tellurides 30a and 30b and their mono‐oxides were prepared and treated with either conc. D 2 SO 4 , NO[BF 4 ], or Tf 2 O (Scheme ) …”

Heterocations in Superacid Systems

“…321 The 125 Te NMR chemical shifts for ions 118 are in the range d 125 Te 1327.3-1343. 322,323 X-ray structure determination of the ditriflate salt of 118 (R ¼ Ph) showed that the Te atom has a distorted trigonal bipyramidal geometry with two apical TeÀS bonds and two equatorial TeÀC bonds, with the lone electron pair occupying the third equatorial position. NMR spectral characteristics indicate that the ions have cistrans or trans-cis configuration [the phenyl group attached to S(1) or S(3) is trans to the other two phenyl groups]; that is, a racemic mixture exists.…”

“…322 Treatment of bis(4-methylphenyl)telluride with NO þ BF 4 À or TfO 2 has afforded dication 121 with NO or O 2 as the oxygen source. 322 Treatment of bis(4-methylphenyl)telluride with NO þ BF 4 À or TfO 2 has afforded dication 121 with NO or O 2 as the oxygen source.…”

“…Aryloxenium cations, however, can be best regarded as cyclohexadienyl ions because of strong delocalization (321b). 316,320 have obtained enium ions of the heavier chalcogen elements stabilized by intramolecular complexation with dimethylamino groups (322). 766 Both ions are ground-state singlets and stabilized by 4-methyl and 4-phenyl substituents.…”