Cornelis Lensink

Ruthenium complexes of chiral diphosphinite ligands with cyclohexane or chiro-inositol backbones as catalysts for asymmetric hydrogenation reactions

Treatment of [RuCl2(COD)] n with the chiral diphosphinite ligand (1S,2S)-1,2-trans-bis-(O-diphenylphosphino)cyclohexane [(1S,2S)-14] and triethylamine gives the bis(diphosphinite) complex RuHCl[(1S,2S)-14]2 (15) in good yield. If (rac)-1,2-trans-bis-(O-diphenylphosphino)cyclohexane [(rac)-14] is used in place of (1S,2S)-14 in this reaction, a racemic mixture of RuHCl[(1S,2S)-14]2 and RuHCl[(1R,2R)-14]2 [(rac)-16] is formed. The X-ray crystal structure of (rac)-16·(2.5CH2Cl2) has been determined. Treatment of (rac)-16 with hydrogen in iso-propanol leads to the formation of a racemic mixture of RuH2[(1S,2S)-14]2 and RuH2[(1R,2R)-14]2 [(rac)-17]. The structure of (rac)-17 was confirmed by the X-ray analysis of a racemic crystal. Ruthenium mono(diphosphinite), diamine complexes of the general formula RuCl2(NN)(PP) are formed by the treatment of RuCl2(PPh3)3 with the appropriate diphosphinite (PP) and diamine (NN) ligands. In this way, the following complexes have been synthesized: RuCl2[(+)-DPEN][(1S,2S)-14] (18), RuCl2[(−)-DPEN][(1S,2S)-14] (19), RuCl2[(+)-DPEN][(1R,2R)-14] (20), RuCl2[(−)-DPEN][(1R,2R)-14] (21), RuCl2[(+)-DPEN][(rac)-14] (22), RuCl2[(−)-DPEN][(rac)-14] (23), RuCl2(D-NN2)[(1S,2S)-14] (24), RuCl2(EDA)[(1S,2S)-14] (25), RuCl2(D-NN2)(D-10) (26), RuCl2(EDA)(D-10) (27), RuCl2[(+)-DPEN](D-10Et) (28), RuCl2(D-NN2)(D-10Et) (29), [where DPEN = 1,2-diphenylethylenediamine, D-NN2 = 1D-1,2-dideoxy-1,2-diamino-3,4,5,6-tetra-O-benzyl-myo-inositol, EDA = 1,2-diaminoethane, D-10 = 1D-3,4-bis(O-diphenylphosphino)-1,2,5,6-tetra-O-methyl-chiro-inositol, D-10Et = 1D-3,4-bis(O-diphenylphosphino)-1,2,5,6-tetra-O-ethyl-chiro-inositol]. These ruthenium complexes catalyze the hydrogenation of the ketones acetophenone and 3-quinuclidinone to give the corresponding alcohols in high yields, but with moderate to low enantiomeric excesses.

Reactivity, structure and electrospray mass spectrometry of pentafluoro- and pentachloro-phenoxy-substituted cyclotriphosphazenes

Abstract The reaction of N3P3Cl6 with the sodium salts of pentachloro- and pentafluorophenol, has been investigated. In contrast to the non-geminal substitution typified by other RO− nucleophiles, the regiochemistry of the reaction of C6X5O− (X=Cl and F) with N3P3Cl6 is dominated by geminal substitution. The reaction of C6Cl5O− with N3P3Cl6 in refluxing tetrahydrofuran yielded gem-N3P3Cl2(OC6Cl5)4 (1) as the major product. The fully substituted derivative N3P3(OC6Cl5)6 (2) was attained in low yield from reaction in refluxing diglyme. In contrast, the reaction of C6F5O− with N3P3Cl6 in refluxing tetrahydrofuran yielded the fully substituted product N3P3(OC6F5)6 (3) after approximately 4 h. 31P NMR spectral results suggest the C6F5O− ion may be attacking in a ‘random’ fashion at low degrees of substitution, which is largely replaced by an electronic geminal-directing effect at tetrasubstitution. Single crystal X-ray crystallographic analyses have been carried out on compounds 1 and 3. Electrospray mass spectrometry has been evaluated as a general technique for characterizing cyclotriphosphazenes, N3P3R6. If R=OEt or OPh, good positive ion spectra are observed but, in contrast, if R is more strongly electron withdrawing (Cl, C6Cl5O or C6F5O) negative ion spectra are obtained.

H...Br hydrogen bonding in trans-bis(acetonitrile-N)tetraaquacobalt(II) dibromide

In the title complex, [Co(CH3CN)2(H2O)4]Br2, the CoII atom lies on an inversion centre and is octahedrally coordinated by two trans acetonitrile molecules and four water molecules. Hydrogen bonding between the water molecules and lattice bromide ions yields a three-dimensional structure.

Bis[(1S*,2S*)-trans-1,2-bis­(diphenyl­phosphin­oxy)cyclo­hexa­ne]chlorido­ruthenium(II) trifluoro­methane­sulfonate dichloro­methane disolvate

The crystal structure of a racemic mixture of the title ruthenium(II) complex, [RuCl(C30H30O2P2)2]CF3SO3·2CH2Cl2, reveals that the coordination geometry about the coordinatively unsaturated metal centre is approximately trigonal-pyramidal, with the chlorine atom occupying one of the equatorial positions. The axial Ru—P bonds are longer than the equatorial Ru—P bonds and there is an acute P—Ru—P angle.

1d-3,4-Di-O-(di­phenyl­methylphos­pho­nio)-1,2,5,6-tetra-O-methyl-chiro-inositol diiodide

The title compound, 3,4,5,6-tetramethoxycyclohexane-1, 2-diyldioxybis(methyldiphenylphosphonium) diiodide, C(36)H(44)O(6)P(2)(2+).2I(-), was prepared from a New Zealand natural product, D-chiro-inositol, in order to develop new catalytic metal complexes. The inositol ring retains its usual chair conformation with only minor perturbations caused by the bound diphenylmethylphosphines. Crystal-packing forces are provided by C-H. I cation-anion interactions.

1-d-3,4-Anhydro-1,2:5,6-di-O-isopropylidene-allo-inositol

The title compound was isolated from the reaction of the 3,4-bis-O-mesylate of 1-D-1,2:5,6-di-O-isopropylidene-chiro-inositol with lithium diphenylphosphide in tetrahydrofuran. The structure consists of independent molecules of 1-D-3,4-anhydro-1,2:5,6-di-O-isopropylidene-allo-inositol, C 12 H 18 O 5 . The two fused dioxolane rings adopt identical envelope conformations around the inositol ring.

3-diphenylphosphino-1,2:5,6-di-O-isopropylidene-4-O-methyl-1D-chiro-inositol

The novel title compound, C25H31O6P, contains rigid fused rings which are shown to be similar to the precursor structures. Weak C-H...O intermolecular interactions produce two-dimensional sheets composed of R(4)4(28) rings.

{N-[2-(η5-Cyclopentadienyl)ethyl]-4-toluenesulfonamido-N,O}(tetrahydrofuran-O)bis(trifluoromethanesulfonato-O)titanium(II)

The title compound, [Ti(CF(3)O(3)S)(2)(C(14)H(15)NO(2)S)(C(4)H(8)O)], contains a unique ligand system in which the Ti ion is bound to the N and O atoms of a 2-p-toluenesulfonamide ligand, which is linked by an ethyl group to a coordinated cyclopentadiene moiety. The distorted octahedral geometry about the Ti ion is completed by two trifluoromethanesulfonate ligands and a tetrahydrofuran molecule. Comparison with related compounds shows that both the Ti-N and Ti-O bonds of the sulfonamide, although longer than normal values, indicate significant bonding interactions.

Bis{μ‐N‐[2‐(η5‐cyclopentadienyl)ethyl]‐4‐toluenesulfonamido‐N,O:O′}bis[bis(trifluoromethanesulfonato‐O)titanium(II)] bis(dichloromethane) solvate

The title compound, [Ti(2)(CF(3)O(3)S)(4)(C(14)H(15)NO(2)S)(2)].2CH(2)Cl(2), consists of unique centrosymmetric dimers, with an eight-membered ring derived from the monomer subunits by formation of two Ti-(N,O)-S-O head-to-tail sequences around a crystallographic inversion centre, and two ordered dichloromethane solvate molecules. The Ti ion has distorted octahedral coordination, through the N atom and one O atom of one p-toluenesulfonamido group linked by an ethyl group to the bound cyclopentadiene moiety, one O atom from the other p-toluenesulfonamido group and two singly bound trifluoromethanesulfonates moieties which are coordinated in pseudo-cis positions. Both Ti-O(sulfonamido) bond lengths [2.149 (3) and 2.388 (3) A] are considered bonding interactions.

1-d-1,2:5,6-Di-O-isopropylidene-3-O-(diphenylphosphinoyl)-chiro-inositol, a hydrogen-bonded dimeric structure

The title compound (C 24 H 29 O 7 P) was prepared from the reaction of chlorodiphenylphosphine with 1-D-1,2:5,6-di-O-isopropylidene-chiro-inositol in pyridine. The structure consists of two independent molecules of 1-D-1,2:5,6-di-O-isopropylidene-3-O-(diphenylphosphinoyl)-chiro-inositol hydrogen bonded to each other, so that the dimer has close to centrosymmetric symmetry in space group P1. Subtle twisting in the fused cyclohexane rings and at the P atoms breaks the centrosymmetry, allowing the formation of strong hydrogen bonds (P=O...H-O 1.9 and 2.0 A).