Systematic structural coordination chemistry of p-tert-Butyltetrathiacalix[4]arene: further complexes of Lanthanide Metal Ions

Extension of previous work on the lanthanide(III) ion complexes of p-tert-butyltetrathiacalix[4]arene has led to a variety of structurally characterised species containing oxo-, hydroxo- and aqua-ligands presumably derived from water present in the preparative medium, along with the thiacalixarene in various stages of deprotonation. The overall stoichiometry of some species is remarkably complicated due to the presence of simple anions and multiple solvents. Simplest is the binuclear complex [(μ-H₂O){Ln(O-dmf)₂}₂(HL·dmf)₂]·nS (dmf = dimethylformamide) [1Ln, Ln = Sm (nS = 2dmf), Eu (nS = 1.5dmf·2MeCN)], also the best-defined of all the arrays studied. The heaviest lanthanides give trinuclear Ln(OH)₃·2Ln(LH)·xdmf·yH₂O (2Ln, Ln = Yb, Lu), while both oxo and hydroxo species are isolable with Eu: trinuclear Eu₃O(L)(LH)(LH₄)·13dmf (3) and tetranuclear Eu₄O(OH)₂(L)(LH₂)₂(LH₄)·12dmf (9), both somewhat atypical species containing uncoordinated thiacalixarene molecules within the lattice. Anion (NO₃, ClO₄) coordination, as in the tri- and tetranuclear species, 4–6Ln, 9, 10Ln, 11Ln, 12, seems especially favoured for the lighter lanthanides. In these arrays, the Ln₃ and Ln₄ aggregates are triangular or (quasi-)square-planar, except for Gd₄O₂(LH₂)₄·2H₂O·2MeOH·2dmf·3.375CH₂Cl₂ (12), where there is a Z-disposition. Most common is an Ln₃O core, which spans the gamut of Ln in three sets of crystal forms with cells of similar dimensions: for Ln = La...Nd, Ln₃(OH)(NO₃)₄(LH₂)₂·4.5dmf (5Ln) (space group C2/m), and Sm...Lu, Ln₃O(NO₃)(LH)₂·4H₂O·2dmso·2MeCN·3py (6Ln) (space group P2₁/n), conformity with crystallographic symmetryentails disorder of the Ln atoms; in a further form of lowersymmetry Pn, (pyH)Ln₃O(NO₃)₂(LH)₂·2MeCN·xH₂O·ydmso·1.5py·MeOH (7Ln, Ln = La, Ce), with no imposed crystallographic symmetry, some disorder persists, but none is found in the crystallographically unrelated form of 8Pr, Pr₃O(NO₃)(LH)₂·16H₂O·2MeCN·5py. Ln₄(OH)(NO₃)₃(L)₂·8dmf·2dmso·3H₂O (10Ln, Ln = Pr...Gd, previously defined for Nd) has a square-planar Ln₄O array sandwiched between a pair of L ligands, with a similar form found for Ln₄O(ClO₄)₂(L₂)·xdmf·yH₂O (11Ln, Ln = La...Nd).