Synthesis, structure, and 13C and 31P CP/MAS NMR of crystalline modifications of the polynuclear thallium(I) O,O′-dicyclohexyl phosphorodithioate complex [Tl{S2P(O-cyclo-C6H11)2}] n
摘要:
Two crystalline modifications (Ia and Ib) of the polynuclear thallium (I) O,O'-dicyclohexyl phosphorodithioate complex [Tl{S2P(O-cyclo-C6H11)(2)}] (n) have been synthesized and characterized by CP/MAS NMR (C-13, P-31). From full P-31 CP/MAS NMR spectra, the chi(2) plots were constructed to calculate the P-31 chemical shift anisotropy P-31 - delta(aniso) = (delta(zz) - delta(iso)) and asymmetry parameters eta = (delta (yy) - delta (xx) )/(delta (zz) - delta(iso)). The data obtained for the O,O'-dicyclohexyl phosphorodithioate (Dtph) groups (in both modifications) are evidence that the P-31 chemical shift tensors are intermediate between rhombic and axially symmetric. However, whereas the rhombic component dominates for Ia, the tensor for Ib is close to axially symmetric (for delta (zz) < delta (yy) a parts per thousand delta (xx) ). The same pattern of the MAS spectra corresponding to negative delta(aniso) (delta (zz) < delta (yy) < delta (xx) ) points to a bridging or terminal/bridging coordination mode of the Dtph groups. X-ray crystallography shows that complex Ib has a polynuclear structure (of the chain polymer type). The chains are composed of alternating structurally nonequivalent noncentrosymmetric binuclear molecules [Tl-2{S2P(O-cyclo-C6H11)(2)}(2)]. All Dtph ligands have the terminal/mu(3)-bridging coordination mode.