Chalcogenide Derivatives of Imidotin Cage Complexes

Abstract

Reaction of the secocubane [Sn3(mu2-NHtBu)2(mu2-NtBu)(mu3-NtBu)] (1) with dibutylmagnesium produces the heterobimetallic cubane [Sn3Mg(mu3-NtBu)4] (4) which forms the monochalcogenide complexes of general formula [ESn3Mg(mu3-NtBu)4] (5a, E = Se; 5b, E = Te) upon reaction with elemental chalcogens in THF. By contrast, the reaction of the anionic lithiated cubane [Sn3Li(mu3-NtBu)4]- with the appropriate quantity of selenium or tellurium leads to the sequential chalcogenation of each of the three Sn(II) centres. Pure samples of the mono- or dichalcogenides are, however, best obtained by stoichiometric redistribution reactions of [Sn3Li(mu3-NtBu)4]- and the trichalcogenides [E3Sn3Li(mu3-NtBu)4]- (E = Se, Te). These reactions are conveniently monitored by using 119Sn NMR spectroscopy. The anion [Sn3Li(mu3-NtBu)4]- also acts as an effective chalcogen-transfer reagent in reactions of selenium with the neutral cubane [{Snmu3-N(dipp)}4] (8) (dipp = 2,6-diisopropylphenyl) to give the dimer [(thf)Sn{mu-N(dipp)}2Sn(mu-Se)2Sn{mu-N(dipp)}2Sn(thf)] (9), a transformation that results in cleavage of the Sn4N4 cubane into four-membered Sn2N2 rings. The X-ray structures of 4, 5a, 5b, [Sn3Li(thf)(mu3-NtBu)4(mu3-Se)(mu2-Li)(thf)]2 (6a), [TeSn3Li(mu3-NtBu)4][Li(thf)4] (6b), [Te2Sn3Li(mu3-NtBu)4][Li([12]crown-4)2] (7b'') and 9 are presented. The fluxional behaviour of cubic imidotin chalcogenides and the correlation between NMR coupling constants and tin-chalcogen bond lengths are also discussed.

Heterocarbenoids of germanium and tin and their polyhedral oxidation products: The case for thermodynamic product control in Group 14 chalcogenides

“…The symmetrical tin amide bonds are rather insensitive to their environment, ranging from 2.070(2) Å for 7 to 2.098(3) Å for 10, with a mean value of 2.085(3) Å . These bonds are somewhat shorter than those reported by Chivers et al for Sn(IV)-N bonds in related Sn-N seco-heterocubes, which range from 2.116(4) to 2.157(5) Å [54][55][56]; they are also shorter than the Sn(IV)-N bonds in an amidinate tin sulfide [35], which were reported to be from 2.09(1) to 2.264(4) Å long.…”

Multi-electron reactivity of a cofacial di-tin(ii) cryptand: partial reduction of sulfur and selenium and reversible generation of S3˙−

“…3). 28 While the 1 H NMR spectrum revealed that the three arms of the cryptand are inequivalent, the 119 Sn NMR data indicate that 3 contains only one tin environment, indicating that a lowering of symmetry from C 3h to C s has occurred through the reaction of 1 with selenium.…”

Chemistry of pnictogen(iii)–nitrogen ring systems

“…Bis(alkylamido)cyclodipnict(III)azanes of the type II are important reagents for the synthesis of the corresponding [RNE(m-NR)] 2 22 dianions. However, with the exception of a single arsenic compound, 52 and two antimony derivatives, 41,53 this has only been realized for cyclodiphosph(III)azanes. The phosphorus derivative [ t BuN(H)P(m-N t Bu)] 2 is readily metallated with n BuLi in THF or toluene to give the dimeric complex [ t BuN(Li .…”