Anna Skarżyńska

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.

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.

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.

4,4,5,5-Tetra­methyl-1,3,2λ5-dioxa­phospho­lan-2-one

The five-membered ring in the title compound, C6H13O3P, exists in an envelope conformation with one of the ring C atoms at the flap position. The coordination geometry around the P atom is a distorted tetrahedron. The crystal structure is stabilized by several weak C—H⋯O and P—H⋯O hydrogen bonds, forming a three-dimensional network.

Carbonylative Suzuki Coupling Reaction Catalyzed by a Hydrospirophosphorane Palladium Complex

A Pd complex with the H‐spirophosphorane ligand, PdCl2{P(OCMe2CMe2O)OC6H4NH2} (Cat. 1), was used as the catalyst in the carbonylative Suzuki coupling of substituted iodobenzenes with arylboronic acids and with sodium tetraphenylborate. Substituted diarylketones were obtained in good to excellent yields and a selectivity over 95 % under 1 atm of CO with 1.5 mol % of the catalyst. The promoting role of the H‐spirophosphorane ligand in the catalytic process was evidenced. We used X‐ray photoelectron spectroscopy, TEM, and 31P NMR spectroscopy to reveal that during the reaction Cat. 1 undergoes transformation into Pd complexes that bear the spirophosphorane ligand or other P ligands formed by its dealkylation and to Pd nanoparticles. All these Pd species contribute to the high productivity of the system.

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.

cis-Dichlorido[2,3-dimethyl-3-(4,4,5,5-tetra­methyl-1,3,2λ5-dioxaphospho­lan-2-yl­oxy)butan-2-olato-κ2O,P]oxido(triphenyl­phosphane-κP)rhenium(V)

The title compound, cis-[Re(C12H24O4P)Cl2O(C18H15P)], was prepared from the analogous trans isomer [Głowiak et al. (2000 ▶). Polyhedron, 19, 2667–2672] by a trans–cis isomerization reaction. The ReV atom adopts a distorted octahedral coordination geometry. Besides being coordinated by the oxide and the butanolate O atoms, the ReV atom is coordinated by a pair of chloride ligands and two P atoms in cis positions with respect to each other. In the crystal, adjacent molecules are linked by weak C—H⋯Cl interactions, forming a three-dimensional network.

trans-Dichloridobis(3,5-dimethyl-pyridine-κN)(ethano-lato-κO)oxido-rhenium(V).

The title compound, [Re(C2H5O)Cl2O(C7H9N)2], was crystallized from ethanol. The crystal structure of this complex contains a Re(V) atom in a slightly distorted octahedral coordination geometry with pairs of equivalent ligands in trans positions. Adjacent complex molecules are linked by weak C—H⋯Cl hydrogen bonds. The crystal structure is additionally stabilized by π–π stacking interactions between the aromatic rings with centroid–centroid distances of 3.546 (4) Å.