The lZ5Te Mossbauer spectra of a number of Te(ll) and Te(1V) complexes of thiourea and related derivatives have been measured. The isomer shifts and quadrupole splittings for several of the compounds are interpreted in terms of a bonding scheme utilizing three-center, two-electron bonds in which the tellurium 5p orbitals participate. The L291 Mossbauer spectrum of ~r a t~s -T e E t u~"~I~ is reported and the isomer shift and quadrupole splitting are shown to be consistent with the proposal that the iodine uses only a 5p orbital in bonding to the tellurium.

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Asymmetry in the Mossbauer spectra of Te(I1) thiourea complexes is shown to be due predominantly, if not exclusively, to single crystal orientation effects. The asymmetry in TeTu4CI, . 2 H 2 0 is consistent with a negative sign for the nuclear quadrupole moment of the $ excited state in lZ5Te.On montre que I'aspect asymktrique dans les spectres Mossbauer des complexes Te(I1). ThiourCe est dii principalement, slnon exclusivement, a des effets d'orientation d'un cristal unique. L'asymetrie dans le spectre du TeTu4C1,.2HZ0 est en accord avec un signe negatif du moment quadruplaire nucleaire de l'etat exclte 3 du lZ5Te.[Traduit par le journal]Can.