Dithiophosphinate complexes of the lanthanides. Preparation of the complexes [Ln{S 2PR 2} 4][AsPh 4], R = OMe, OPr i. Determination of the crystal structurals for Ln = Ce, Er (R = OMe) and Ln = Nd, Ho (R = OPr i)

Abstract

Lanthanide ions react with the salts of the dithiophosphorus acids R 2PS 2H (R = OMe, OPr i) in the corresponding alcohol to form the tetrakis anionic complexes which may be isolated as their tetraphenylarsonium salts. For R = OPr i, the complexes of the heavy ions crystallise as solvates, the solvent being easily removed in vacuo. The crystal structures of the complexes [Ln{S 2PR 2} 4] [AsPh 4] have been determined from diffractometer data for Ln = Ce and Er, R = OMe; and Ln = Nd and Ho, r = OPr i. [Ce{S 2P(OMe) 2} 4] [AsPh 4]: monoclinic, space group Cc with a = 14.762(3), b = 16.780(4), c = 19.890(3) Å and β = 101.09(1)°, R = 0.041. [Er{S 2P(OMe) 2} 4] [AsPh 4]: isomorphous to the above with a = 14.626(3), b = 16.760(2), c = 19.718(1) Å and β = 100.89(1)°, R = 0.056. [Nd{S 2P(OPr i) 2} 4] [AsPh 4]: monoclinic, space group P2 1/c with a = 12.868(4), b = 24.966(4), c = 21.420(6) Å and β = 102.32(2)°, R = 0.072. Ho{S 2P(OPr i) 2} 4] [AsPh 4] · Pr iOH: monoclinic, space group P2 1/n with a = 14.401(3), b = 32.427(6), c = 15.168(2) Å and β 93.46(1)°, R = 0.069. The lanthanide ions are surrounded by eight sulphur atoms (CeS = 2.969, NdS = 2.984, HoS = 2.865, ErS = 2.856 Å) in an almost perfect D 2d dodecahedral arrangement (mmmm isomer). The Ho complex contains a molecule of uncoordinated lattice solvent. The solid state structures are compared with results obtained from paramagnetic NMR experiments in solution.