SULFURANES WITH OXIMATE AXIAL LIGANDS

New sulfuranes having one or two axial oximate (R(2)C=NO) ligands were synthesized. An improved sulfurane-forming step, involving a rapidly stirred suspension of NaHCO3, is described. The failure of sulfide oxi mes in which sulfur bears one or two tertiary carbons to form sulfuran es is explained by a C-S bond cleavage leading to tertiary carbocation s. This represents a hitherto unanticipated limitation to the standard method of sulfurane synthesis. The X-ray crystal structure of one of the new sulfuranes, namely 2,2'-spirobi(4-phenyl-3H-1,2,5-oxathiazo is reported (R = 0.0368). An unusual feature was the quite compressed eq uatorial(C-S-C) angle, 102.6(1)degrees. The S-O bond length, 1.846(2) Angstrom, was similar to S-O bond lengths of sulfuranes having two axi al carboxylate ligands. Since the oximate ligand has not been used pre viously in a 10-S-4 species, an assessment of its apicophilicity relat ive to other more common axial ligands was made by considering X-ray s tructural data, IR data, and ab initio calculations. These suggest tha t the R(2)C=NO ligand is as apicophilic as the hexafluorocumyloxy (ArC (CF3)(2)O) ligand.