CONTRIBUTIONS TO THE CHEMISTRY OF SILICON-SULFUR COMPOUNDS .65. SYNTHESIS, CRYSTAL AND MOLECULAR-STRUCTURE OF LO-TETRAKIS[TRI-TERT-BUTOXYSILANETHIOLATOGOLD(I)], [(T-C4H9O)3SISAU]4, THE 1ST EXAMPLE OF AN AU4S4 RING-SYSTEM

The preparation of the first silanethiolate complex of gold, clo-tetra kis[tri-tert-butoxysilanethiolatogold(I)] from tri-tert-butoxysilaneth iol and tetrachloroauric acid is described. The compound forms colorle ss orthorhombic crystals, and the molecular structure was determined a t 200 K by single crystal X-ray diffraction. At 187 K, a possible, rev ersible phase transition is observed. The center of the molecule is a distinctly folded eight-membered Au4S4 ring of alternating three-fold coordinated sulfur and two-fold coordinated gold atoms. The relevant b ond lengths and angles are: Au-S 228.4 and 229.6 pm, Si-S216.9 pm, S-A u-S 178.8-degrees and 178.3-degrees, Au-S-Au 90.3-degrees, Si-S-Au 103 .7-degrees and 101.9-degrees. The gold atoms are separated by 324.8 pm .