Lithium tetraorganodichalcogenoimidodiphosphinates. Crystal structure of [Li{(OPPh_2)(SPMe_2)N}·2H_2O]_2, a dimer formed through oxygen-bridging phosphorus ligands

摘要

Lithium tetraorganodichalcogenoimidodiphosphinates, Li[(XPR_2)(YPR;)N], were prepared and investigated by means of IR and multinuclear (IH, ~(13)C, ~(31)P) NMR spectroscopy. The crystal and molecular structure of lithium P,P-dimethyl-P',P'-diphenyl- P-thioimidodiphosphinate was determined by X-ray diffraction. The asymmetric unit contains two independent dimeric associa- tions, [Li{(OPPh_2)(SPMe2)N}.2H_2O]_2. built up through O-phosphorus ligand bridges and separated by normal van der Waals distances. This results in the formation 0( a perfectly planar Li2O2 four-membered cycle with tetrahedral coordination around each metal atom completed by two additional O-water atoms. The sulfur atoms of the monothioimidodiphosphinato groups, which are not involved in coordination to a metal center, are on opposite sides of the Li_2O_2 cycle.