| Abstract
| - Tellurium diimide dimers of thetype RNTe(μ-NR‘)2TeNR are prepared by the reactionsof (a) the PN2Te heterocyclePh2PN(SiMe3)2Te(Cl)NR(R = PPh2NSiMe3) with R‘NHLi (R‘ =tBu, tOct) and (b) TeCl4with tBuNHLi in a 1:4 molar ratio. The crystalstructures of these dimers consist of a four-memberedTe2N2 ring with the short, exocyclic TeNRbonds arranged in either a cis (R = R‘ =tBu) or trans (R = tBu,tOct; R‘ = PPh2NSiMe3)orientation. The trans isomers slowly convert into thecorresponding cis isomers in solution. The reaction ofPh2PN(SiMe3)2Te(Cl)NPPh2NSiMe3with2,4,6-tBu3C6H2NHLiproduces the telluradiazole dimer(tBu2C6H2N2Te)2.
- The reaction of R‘NHLi (R = tBu,tOct) withPh2P(NSiMe3)2Te(Cl)NPPh2NSiMe3in toluene at −78 °C, followedby warming to 23 °C, produces the tellurium diimide dimersRNTe(μ-NR‘)2TeNR (2a, R‘ =tBu, R = NPPh2NSiMe3; 2b, R‘ = tOct, R =NPPh2NSiMe3) andPh2P(NHSiMe3)(NSiMe3).X-ray analyses revealed that 2a and2b have centrosymmetric structures containing a planarfour-membered Te2N2 ring and short exocyclictellurium−nitrogen bond lengths (d(Te−N) = 1.900(5) and1.897(4) or 1.905(4) Å for 2a and 2b,respectively). The exocyclicimido substituents adopt a trans arrangement with respect tothe Te2N2 ring. By contrast, the reactionof 2,4,6-tBu3C6H2NHLiwithPh2P(NSiMe3)2Te(Cl)NPPh2NSiMe3in toluene under similar conditions produces thetelluradiazole(tBu2C6H2N2Te)2(3), which exists as a weakly associated dimer in the solidstate with intramolecularTe−N distances of 2.628(4) Å. The tellurium diimide dimertBuNTe(μ-NtBu)2TeNtBu(2c‘), prepared by thereaction of TeCl4 with tBuNHLi in a 1:4molar ratio, consists of a folded Te2N2 ringwith exocyclic NtBu groupsin a cis orientation. The 1H,31P, and 125Te NMR spectra of2a and 2b indicate that the transisomers slowlytransform into the corresponding cis isomers in solution.Crystals of 2b are triclinic, space groupP1̄ (No. 2),with a = 13.304(3) Å, b =16.927(3) Å, c = 13.292(5) Å, α =98.94(2), β = 109.27(2), γ = 69.04(2)°,V =2636(1) Å3, and Z = 4. The finalR and Rw values were 0.034 and 0.033,respectively. Crystals of 2c‘ areorthorhombic, space group Pnma (No. 62), with a= 9.535(3) Å, b = 14.264(3) Å, c= 16.963(4) Å, V = 2307.1(9)Å3, and Z = 4. The final Rand Rw values were 0.040 and 0.040,respectively. Crystals of 3 aremonoclinic,space group P21/n (No. 14), witha = 9.117(3) Å, b = 11.481(4) Å,c = 16.550(4) Å, β = 97.76(2)°,V =1716.5(8) Å3, and Z = 4. The finalR and Rw values were 0.031 and 0.034,respectively.
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