Formation of N−I Charge-Transfer Bonds and Ion Pairs in Polyiodides with Imidotellurium Cations

[(tBuNH)Te(μ-NtBu)2Te(NtBu)][OSO2CF3] (4a) is obtained in quantitative yields by the treatment of [(tBuN)Te(μ-NtBu)2Te(NtBu)] (1) with HCF3SO3. The reaction of 4a with LiI and iodine in the molar ratio 1:1:4.5 affords a
product that, upon recrystallization from acetonitrile, was found to be a solid solution of [(tBuNH)Te(μ-NtBu)2Te(NtBu)]2I20 (5a) and [(tBuNH)Te(μ-NtBu)2Te(NHtBu)]2I18 (5b). Consequently, the crystal structure is disordered,
containing 88.3(1)% of 5a·2MeCN and 11.7(1)% of 5b·2MeCN. The I20 framework is involved in two symmetry-equivalent N−I−I−I−I fragments, two I3- ions, and three I2 molecules that are linked together by I···I secondary
bonding interactions. The bonding in the N−I−I−I−I fragment can be considered in terms of the lp(N) → σ*(I2) and
π*(I2) → σ*(I2) charge-transfer interactions involving one [(tBuNH)Te(μ-NtBu)2Te(NtBu)]+ cation and two I2 units.
The N−I bond length of 2.131(7) Å, the I−I distances of 3.118(1), 3.095(2), and 2.788(2) Å, and the ∠I2 −I2 angle
of 84.75(4)° are consistent with this bonding scheme. The I−I bond distances in the two symmetry-equivalent I3-
ions are 3.113(1) and 2.792(2) Å, and those in two crystallographically independent I2 molecules are 2.736(2) and
2.743(1) Å. The formal I184- anion in 5b·2MeCN consists of four I3- anions and three I2 molecules linked by I···I
secondary bonds. One crystallographically independent I3- anion is connected to the [(tBuNH)Te(μ-NtBu)2Te(HNtBu)]2+ cation by two hydrogen bonds [H···I = 2.823(5) and 2.983(5) Å; N···I = 3.697(8) and 3.857(9) Å].
The I3- anions and I2 molecules in 5b show virtually identical bond parameters to those in 5a. The treatment of
1 with iodine and the reactions of its methylated derivatives, [(tBuNMe)Te(μ-NtBu)2Te(NtBu)][OSO2CF3] and [(tBuNMe)Te(μ-NtBu)2Te(MeNtBu)][OSO2CF3]2, with LiI and iodine also afford highly moisture-sensitive polyiodides, either by
the formation of N−I charge-transfer complexes or by ionic interactions. The crystal structures of the partially
hydrolyzed products, [(tBuIN)Te(μ-NtBu)2Te(μ-O)]2(I3)2 (3), [(tBuMeN)Te(μ-NtBu)2Te(μ-O)]2(I3)2 (6), and 6·2MeCN,
are also reported.