Witold K. Rybak

Dehydrogenation of alcohols catalyzed by polystyrene-supported ruthenium complexes

Abstract The dehydrogenation reaction of alcohols catalyzed by Ru(O 2 CCF 3 ) 2 (CO)(PPh 3 ) 2 complex (1) attached to polystyrene, functionalized with phosphine [1-A] and carboxylic [1-B] groups, singly or together [1-C], give as products aldehydes and molecular hydrogen. Comparison of the relative rates for the heterogenized [1-A], [1-B] and [1-C] catalysts and for the ruthenium complex (1) in a homogeneous system indicates a similar reaction mechanism in each case.

Ligand Scavenging and Catalytic Utilization of the Phototransient ReH5(PMe2Ph)2

Abstract Photogenerated ReH 5 P 2 (P = P(CH 3 ) 2 C 6 H 5 ) effects hydrogen exchange selectively at the β-carbons of naphthalene. Under one atm

Synthesis and structural characterisation of the oxo-rhenium(V) complexes with spirophosphorane derived bidentate ligand (P∼O−). Crystal structure of trans-ReOCl2[OCMe2CMe2OP(OCMe2CMe2O)](PPh3)

Abstract The reactions of ReO(OEt)Cl2L2, L=py, PPh3 or ReOCl3(Me2S)(OPPh3), with spirohydrophosphorane HP(OCMe2CMe2O)2 – abbreviated here as HP∼O – in toluene yield ReOCl2(P∼O)L complexes, L=py (1), PPh3 (2) and OPPh3 (3), respectively. The encountered bidentate phosphite pinacolato (OCMe2CMe2O)POCMe2CMe2O− ligand (P∼O−) is afforded by means of a spirophosphorane ring-opening reaction. All the pink–violet compounds 1–3 were characterised by NMR, IR and UV–Vis spectroscopies. The structure of trans-ReOCl2(P∼O)PPh3 (2) was determined crystallographically. The rhenium atom adopts distorted octahedral geometry with a trans multiply bonded terminal oxo ligand (Re–Ot=1.698(2) A) trans to pinacolate oxygen (Re–O=1.880(2) A). Two phosphorus atoms as well as two chlorides are mutually in a trans arrangement.

Synthesis, Structure and Catalytic Activity of An Oxorhenium(V) Complex Containing Chelating Phosphite Ligand

Abstract The new violet oxorhenium(V) complex ReOCl3(pinacop) {pinacop = (OCMe2CMe2O)POCMe2CMe2OP (OCMe2CMe2O)} was obtained by reaction of ReOCl3(OPPh3)(SMe2) with a stoichiometric amount of pinacop. Facial geometry was determined by spectroscopic means and preliminary results from an X-ray crystallographic study. The catalytic properties of the title compound in oxygen atom transfer reactions are discussed.

Oxo-rhenium(V) complexes containing bridging phosphito ligands. The synthesis, characterisation and X-ray crystal structures of [ReOCl{μ-OP(OR)2}{OCMe2CMe2OP(OCMe2CMe2O)}]2 (R=Me or CMe2)

Abstract The oxo-rhenium(V) complexes [ReOCl2(P∼O)L] (P∼O=(OCMe2CMe2O)POCMe2CMe2O−), L=py (1), PPh3 (2) or OPPh3 (3)) react with P(OMe)3 or spirophosphorane HP(OCMe2CMe2O)2 (HP∼O) affording the related μ-phosphito(1−) bridged dimeric compounds [ReOCl{μ-OP(OR)2}(P∼O)]2 (R=Me (4) or CMe2 (5)). The μ-phosphito ligands result from Arbuzov-like dealkylation reactions. Complexes 4 and 5 were characterised by NMR, IR, UV–VIS spectroscopic methods. In solution, both the light brown complexes 4 and 5 remain dimeric and comprise two equivalent six-coordinated monomeric subunits stereochemically rigid at ambient temperature. The complexes appeared to be rather inert in attempted substitution reactions. In the crystal state, in spite of the molecular Ci symmetry of 4, complex 5 reveals a distorted pseudocentrosymmetric C1 geometry. The multiply bonded terminal oxo ligands (ReO 1.681(5) A (4), 1.684(5) and 1.691(5) A (5)) are in cis arrangements to two phosphito bridges. Two different phosphito bridged cores Re{μ-OP(OR)2}2Re (R=Me (4), CMe2 (5)) adopt the chair conformation.

Synthesis, characterization and reactivity of some rhenium phosphite complexes

Abstract The preparation and characterization of some Re(III), Re(IV) and Re(V) chloro phosphite complexes are reported. Both Re(III) and Re(IV) complexes react with sodium borohydride, yielding the corresponding polyhydrides, ReH5[P(OEt)3]3 and ReH7[P(OEt)3]2. The thermal and photochemical reactivity of these complexes is described.

Enantiomeric enrichment of a nonracemic conglomerate of a chiral oxo-rhenium(v) complex

The enantiomer being in excess was readily recovered from a nonracemic conglomerate of chiral cis-[ReOCl2{OCMe2CMe2OP(OCMe2CMe2O)}py] by means of a difference in solubility between the enantiomer and the racemate; subsequently the solubility diagram and the specific optical rotation [α]589=+1345 (±30 max. absolute error; c=0.05 g per 100 cm3 in MeCN) for the pure enantiomer of the absolute configuration C was also determined.

Tuning enantioselectivity for crystallization-induced asymmetric synthesis of a conglomerating oxo-rhenium(V) complex

Crystallization-induced asymmetric synthesis of conglomerates could be an innovative and powerful tool in the enantioselective preparation of compounds without any chiral auxiliaries but with requirement of appropriate adjustment of the reaction conditions. It is demonstrated that synthesis of the conglomerating chiral oxo-rhenium(V) complex cis-[ReOCl2(P∼O)py] (P∼O = (OCMe2CMe2O)–POCMe2CMe2O(1−)), yielding practically racemate can be made extremely enantioselective by fine-tuning the reaction conditions.