18252-66-9Relevant articles and documents
Synthesis and multinuclear NMR studies of [M{o-C6H4(TeMe)2}X2] (M = Pd, Pt; X = Cl, Br, I). The presence of a characteristic ring contribution to 125Te NMR chemical shifts
Kemmitt, Tim,Levason, William
, p. 731 - 735 (2008/10/08)
The complexes [M{o-C6H4(TeMe)2}X2] (M = Pd, Pt; X = Cl, Br, I) and [NnBu4] [Ir{o-C6H4(TeMe)2}X4] (X = Cl, Br) have been prepared, and characterized by analysis and UV-visible, IR, and multinuclear (1H, 125Pt{1H}, 125Te{1H}) NMR spectroscopy. Two isomers, meso and dl invertomers, are present in each complex. The coordination shifts in the 125Te NMR spectra of the Pd and Pt complexes are compared with those reported for [M{PhTe(CH2)3TePh}X2] and for the analogous cis-[M(TeMePh)2X2]. It is found that, compared with the monodentate complexes, the chelate complexes having five-membered rings exhibit large high frequency coordination shifts and those having six-membered rings have small low frequency shifts. Data on complexes of o-C6H4(TePh)2 and MeTe(CH2)3TeMe compared with data for TePh2 and TeMe2 complexes show similar effects, which are rationalized in terms of a characteristic chelate ring contribution , defined as ΔR, to the shifts of the bidentate telluroethers. Similar phenomena are known for 31P and 77Se shifts in analogous complexes, but this is the first demonstration of the effect in 125Te NMR.
