MULTIFUNCTIONAL PHOSPHANE AND PHOSPHANE OXIDE LIGANDS DERIVED FROM P-TERT-BUTYLCALIX[4]ARENE - SYNTHESIS OF A LARGE DIPHOSPHANE WITH C2 SYMMETRY AND BEHAVING AS A CIS OR TRANS BINDING LIGAND

The calix[4]arene derived di(phosphane oxide) 2 (cone conformation) was obtained in 78% yield by treatment of 1 with 2 equiv NaO(t)Bu followed by reaction with 2 equiv Ph2P(O)CH2OTs. When KO(t)Bu was used instead of NaO(t)Bu, the partial cone isomer 2' was formed. Reaction of 2 with PhSiH3 in refluxing toluene afforded quantitatively the mixed di(ester)-di(phosphane) ligand 3; crystal data of 3: monoclinic, C21c; a = 24.091(7), b = 14.416(4), c = 25.270(8) angstrom, beta = 128.07(2)-degrees, V = 6909.1(5) angstrom3, Z = 4 and R(F) = 5.8%. The molecule which lies on a C2 axis adopts a distorted cone conformation; the angle formed between the ester substituted phenolic rings is 10.5(2)-degrees and that between the phosphane substituted rings is 95.0(1)-degrees. The phosphorus lone pairs point towards the exterior of the space defined by the four calixarene substituents, whereas the two ester groups are directed to the interior of this cavity. Ligand 3 reacts with [PtCl2(PhCN)2] in THF to yield cis-PtCl2 . 3 (4) in 91% yield. The sequential reaction of [RhCl(1,5-cyclooctadiene)]2 with 2 equiv AgBF4 and 2 equiv 3 gave the cationic complex cis-[Rh(1,5-cyclooctadiene) . 3](BF4) (5). Reaction of carbon monoxide with commercial RuCl3 in boiling 2-ethoxyethanol and subsequent addition of 3 gave cis-cis-trans-P,P-[RuCl2(CO)2 . 3] (6). Complexes 4-6 display fluxional behaviour in solution. All compounds were characterized by elemental analysis and IR and H-1, P-31, and C-13 NMR spectroscopy.