P Chemical Shifts in Ru(II) Phosphine Complexes. A Computational Study of the Influence of the Coordination Sphere.

The NMR chemical shift has been the most versatile marker of chemical structures, by reflecting global and local electronic structures, and is very sensitive to any change within the chemical species. In this work, Ru(II) complexes with the same five ligands and a variable sixth ligand L (none, HO, HS, CHSH, H, N, NO, NO, C═CHPh, and CO) are studied by using as the NMR reporter the phosphorus P of a coordinated bidentate P-N ligand (P-N = -diphenylphosphino-,'-dimethylaniline). The chemical shift of P in RuCl(P-N)(PR)(L) (R = phenyl, -tolyl, or -FCH) was shown to increase as the Ru-P bond distance decreases, an observation that was not rationalized.

Binding of CO and NH3 at a five-coordinate Ru(II) centre in the solid state and in solution.

The known five-coordinate, square-pyramidal, green trans-RuCl2(P-N)(PR3) complexes (P-N = o-diphenylphosphino-N,N'-dimethylaniline; R = Ph (1a), p-tolyl), in the solid state at ambient conditions, or in CDCl3 solution at low temperatures, coordinate CO (at 1 atm) to form beige-coloured trans-monocarbonyl derivatives. In the solution reactions at room temperature, the PR3 ligand dissociates and the yellow dicarbonyl complex RuCl2(CO)2(P-N) is formed as a mixture of trans,cis- and cis,cis-isomers. With use of (13)CO, the carbonyls complexes are characterized by variable temperature NMR and IR data, and (for the monocarbonyls) elemental analyses.

Comparative properties of coordinated H2 and H2S at a ruthenium(II) centre.

Thermodynamic data for the reversible formation of cis-RuCl2(P-N)(PPh3)(η(2)-H2) () from trans-RuCl2(P-N)(PPh3) in C6D6 are determined by variable temperature (31)P{(1)H} and (1)H NMR spectroscopy; P-N = o-diphenylphosphino-N,N'-dimethylaniline. Values of ΔH° = -26 ± 4 kJ mol(-1), ΔS° = -40 ± 15 J mol(-1) K(-1), and ΔG° (at 25 °C) = -13.8 ± 0.

Dioxygen adducts of rhodium N-heterocyclic carbene complexes.

Rhodium complexes functionalized by N-heterocyclic carbene ligands react with dioxygen to form adducts. Depending on the specifics of the ancillary ligands, oxygen binds to Rh either as a peroxide to form a fully oxidized Rh(III) complex, or as singlet dioxygen in a Rh(I) square planar complex. We have shown through analysis of a series of compounds, some previously published and some novel, that the presence of additional ligands that would support the formation of an octahedral geometry, as typically found with Rh(III) complexes, is critical for formation of the peroxide.

Reversible binding of water, methanol, and ethanol to a five-coordinate ruthenium(II) complex.

The known green, five-coordinate, square-pyramidal trans-RuCl(2)(P-N)(PPh(3)) complex reversibly binds water, MeOH and EtOH in the vacant coordination site in the solid state and in CH(2)Cl(2) solution to give pink adducts (P-N = o-diphenylphosphino-N,N'-dimethylaniline). The adducts are well characterized, including X-ray analysis of the aqua complex, trans-RuCl(2)(P-N)(PPh(3))(H(2)O), which crystallizes in two different benzene-solvated forms. Comparison of the structural data with those determined previously for the binding of H(2)S, thiols, and H(2), which form cis-RuX(2)(P-N)(PPh(3))L products (X = Cl, Br; L = a S-ligand or H(2)) reveals the trans-influence trend P > H(2)S ~ thiols > H(2) > Cl ~ Br > H(2)O.

Molecular recognition using ruthenium(II) porphyrin thiol complexes as probes.

In situ (1)H NMR data are reported for 106 Ru(porp)(RSH)(2) species, where porp is the dianion of β-octaethylporphyrin (OEP), meso-tetraphenylporphyrin (TPP), and its para-substituted tetraphenyl analogues (T-p-XPP; X = OMe, Me, F, Cl, CO(2)Me, CF(3)), meso-tetrakis(3,5-dimethylphenyl)porphyrin (T-m,m'-Me(2)PP), and meso-tetramesitylporphyrin (TMP), and R = Me, Et, (n)Pr, (i)Pr, (n)Bu, (t)Bu, (n)Hex, Bn (benzyl), Ph, and p-MeOC(6)H(4). The upfield shifts in the SH resonances upon coordination of the thiol reflect changes in the porphyrin ring current and are analyzed using an empirical model that depicts quantitatively the nonbonding, electronic, and steric interactions between the thiol ligands, where steric factors dominate, and the porphyrin plane, where electronic factors dominate; such interactions are typically involved in small-molecule recognition within metalloporphyrin systems. Implications of the findings to hemethiolate proteins and surface coordination chemistry are also briefly presented.

Hydrogenolysis of β-O-4 lignin model dimers by a ruthenium-xantphos catalyst.

Hydrogenolysis reactions of so-called lignin model dimers using a Ru-xantphos catalyst are presented (xantphos = 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene). For example, of some nine models studied, the alcohol, 2-(2-methoxyphenoxy)-1-phenylethanol (1), with 5 mol% Ru(H)(2)(CO)(PPh(3))(xantphos) (18) in toluene-d(8) at 135 °C for 20 h under N(2), gives in ~95% yield the C-O cleavage hydrogenolysis products, acetophenone (14) and guaiacol (17), and a small amount (<5%) of the ketone, 2-(2-methoxyphenoxy)-1-phenylethanone (4), as observed by (1)H NMR spectroscopy. The in situ Ru(H)(2)(CO)(PPh(3))(3)/xantphos system gives similar findings, confirming a recent report (J.

Ruthenium(II) thiol and H2S complexes: synthesis, characterization, and thermodynamic properties.

The known, green, five-coordinate species trans-RuCl(2)(P-N)(PPh(3)) react with R'SH thiols to give yellow cis-RuCl(2)(P-N)(PPh(3))(R'SH) products (P-N = o-diphenylphosphino-N,N'-dimethylaniline; R' = alkyl). The MeSH and EtSH compounds are structurally characterized, with the former being the first reported for a transition metal-MeSH complex, while the thiol complexes with R' = (n)Pr, (i)Pr, (n)Pn (pentyl), (n)Hx (hexyl), and Bn (benzyl) are synthesized in situ. Other trans-RuX(2)(P-N)(PR(3)) complexes (X = Br, I; R = Ph, p-tolyl) are synthesized, and their H(2)S adducts, of a type reported earlier by our group, are also prepared.

Thiol, disulfide, and trisulfide complexes of Ru porphyrins: potential models for iron-sulfur bonds in heme proteins.

Thirty-two Ru(porp)L(2) complexes have been synthesized, where porp = the dianion of meso-tetramesitylporphyrin (TMP) or meso-tetrakis(4-methylphenyl)porphyrin (H(2)T-pMe-PP), and L = a thiol, a sulfide, a disulfide, or a trisulfide. Species studied were with RSH [R = Me, Et, (n)Pr, (i)Pr, (t)Bu, Bn (benzyl), and Ph], RSR (R = Me, Bn), RSSR (R = Me, Et, (n)Pr, Bn) and MeSS(t)Bu, and RSSSR (R = Me, Bn). All the species except two, which were the isolated Ru(T-pMe-PP)((t)BuSH)(2) and Ru(TMP)(MeSSMe)(2), were characterized in situ.

Reactivity of the bridged-sulfide complex Pd2Cl2(μ-S)(μ-dmpm)2 toward electrophiles.

The dipalladium(I) complex Pd(2)Cl(2)(dmpm)(2) (1a) [dmpm = bis(dimethylphosphino)methane] is known to react with elemental sulfur (S(8)) to give the bridged-sulfide complex Pd(2)Cl(2)(μ-S)(dmpm)(2) (2a) but, in the presence of excess S(8), PdCl(2)[P,S-dmpm(S)] (4a) and dmpm(S)(2) are generated. Treatment of 1a with elemental selenium (Se(8)), however, gives only Pd(2)Cl(2)(μ-Se)(dmpm)(2) (3a). Complex 4a is best made by reaction of trans-PdCl(2)(PhCN)(2) with dmpm(S).

Reactions of the bis(dialkylphosphino)methane complexes Pd2X2(μ-R2PCH2PR2)2 (X = halogen, R = Me or Et) with H2S, S8, COS, and CS2; detection of reaction intermediates.

The Pd(2)X(2)(dmpm)(2) complexes [X = Cl (1a), Br (1b), I (1c); dmpm = bis(dimethylphosphino)methane. In all the dipalladium complexes mentioned in this paper, the dmpm, depm, and dppm ligands (unless stated otherwise) are bridging, but for convenience the μ-symbol is omitted.] react with H(2)S to yield H(2) and the bridged-sulfido complexes Pd(2)X(2)(μ-S)(dmpm)(2) (2a-c), of which 2a and 2b are structurally characterized.

Reactions of a phosphinoaldehyde with Pd(II), Rh(I), and Ir(I) precursors, including the formation of complexes containing a P,OH-chelated phosphinohemiacetal ligand: a new bonding mode.

The complexes trans-PdCl(2)[eta(1)-P-(Ph(2)P)CH(Ph)CH(Me)CH(OMe)(2)](2) (1) and M(H)Cl[eta(2)-P,OH-(Ph(2)P)CH(Ph)CH(Me)CH(OH)OMe][eta(2)-P,C(O)-(Ph(2)P)CH(Ph)CH(Me)C(O)], M = Rh (3) and Ir (4), are synthesized by reacting the phosphinoaldehyde [3-(diphenylphosphino)-3-phenyl-2-methyl]propionaldehyde [(Ph(2)P)(2)CH(Ph)CH(Me)CHO] with trans-PdCl(2)(PhCN)(2), [RhCl(COD)](2), and [IrCl(COD)](2), respectively, in MeOH; trans-PdCl(2)[eta(1)-P-(Ph(2)P)CH(Ph)CH(Me)CHO](2) (2) is isolated from the same reaction in CH(2)Cl(2). One diastereomer of each of the complexes 1, 3 x MeOH, and 4 x MeOH was characterized by X-ray analysis. The stereochemistry of such complexes in the solid state and in solution (MeOH and CH(2)Cl(2)) is discussed.

Reactions of tertiary phosphines with alcohols in aqueous media.

The phosphines R(2)R'P [R = R' = Me, Et, (n)Pr, (i)Pr, (CH(2))(3)OH; Me(2)PhP and MePh(2)P] react with 2- or 4-hydroxybenzyl alcohols, including "lignin-type" vanillyl, syringyl, and alpha-methylvanillyl alcohols, in a 1:1 ratio in aqueous media, to give zwitterionic phosphobetaine products; these on treatment with aq HCl form the corresponding phosphonium chlorides in good to excellent yields. The syringyl derivative [3,5-(OMe)(2)-4-OH-C(6)H(2)CH(2)PEt(3)]Cl was structurally characterized by X-ray analysis. Kinetically, the reactivity of the benzyl alcohols, studied with the water-soluble [HO(CH(2))(3)](3)P, decreases with substituents in the order 2-hydroxy > 4-hydroxy > vanillyl > syringyl > alpha-methylvanillyl, while 3-hydroxybenzyl alcohol is unreactive; the trend is consistent with reactivity requiring the presence of an ortho- or para-OH substituent in the aromatic ring of the alcohol, and that the reactions proceed via a carbocation species stabilized as a quinone methide.

Synthetic and mechanistic aspects of a new method for ruthenium-metalation of porphyrins and Schiff-bases.

A new method is presented for metalation of a wide range of free-base, neutral, cationic, and anionic porphyrins in refluxing dimethylformamide (DMF) using an easily prepared [Ru(DMF) 6](OTf) 3 complex, and comparisons are made with the more familiar metalation procedure using Ru 3(CO) 12. Both procedures generate Ru (II)(porp)(CO)L complexes (L = solvent); use of the Ru (III)-triflate precursor gives yields comparable to, or greater than, those obtained with the carbonyl, and generates no Ru-chlorin impurities. Mechanistic studies on the meso-tetraphenylporphyrin system reveal that the DMF furnishes the CO, which in the presence of essential water reduces the metal, and metalation likely occurs via a Ru (II)-CO species.

Chloridotris[tris-(4-fluoro-phen-yl)phosphine]rhodium(I) methanol solvate.

In the title compound, [RhCl{P(p-FC(6)H(4))(3)}(3)]·CH(3)OH, the Rh atom adopts a distorted square-planar geometry. Rh, Cl and one P atom lie on a mirror plane, as does the solvent molecule. There are two inter-molecular hydrogen bonds, one between the methanol O atom and an aryl H atom (2.

trans-Carbonyl-chloridobis(tri-p-tolyl-phosphine)rhodium(I) acetone solvate.

The title compound, [RhCl(C(21)H(21)P)(2)(CO)]·C(3)H(6)O, was precipitated in trace yield from a reaction of RhCl(cod)(THP) with P(p-tol)(3) in a 1:1 acetone-d(6)/CD(3)OD solution under a hydrogen atmosphere [p-tol = p-tolyl, THP = tris-(hydroxy-meth-yl)phosphine, P(CH(2)OH)(3), and cod = 1,5-cyclo-octa-diene]. The complex displays a square-planar geometry around the Rh(I) atom. The complex mol-ecules and the acetone mol-ecules are linked into a chain along the a axis by inter-molecular C-H⋯Cl and C-H⋯O hydrogen bonds.

New tertiary phosphines from cinnamaldehydes and diphenylphosphine.

A 1:1 hydrophosphination of the olefinic bond of cinnamaldehyde (and substituted ones) with Ph2PH, under argon using neat reagents, gives quantitative formation of the new tertiary phosphines Ph2PCH(Ar)CH2CHO (2) as racemic mixtures (Ar = Ph, p-tol, and p-OMe-C6H4). alpha-Methylcinnamaldehyde similarly affords Ph2PCH(Ph)CH(Me)CHO, but as a mixture of diastereomers with predominantly S,S- and R,R-chirality [diastereomeric ratio (dr) approximately 20]. In a 2:1 reaction of Ph2PH with cinnamaldehyde, hydrophosphination of both the C=C and C=O bonds takes place to give the diphosphine derivative Ph2PCH(Ph)CH2CH(OH)PPh2 (3) as a diastereomeric mixture with dr approximately 2.

Interaction of tertiary phosphines with lignin-type, alpha,beta-unsaturated aldehydes in water.

To learn more about the bleaching action of pulps by (hydroxymethyl)phosphines, lignin chromophores, such as the alpha,beta-unsaturated aromatic aldehydes, sinapaldehyde, coniferylaldehyde, and coumaraldehyde, were reacted with the tertiary phosphines R2R'P [R = R' = Me, Et, (CH2)3OH, iPr, cyclo-C6H11, (CH2)2CN; R = Me or Et, R' = Ph; R = Ph, R' = Me, m-NaSO3-C6H4] in water at room temperature under argon. In all cases, initial nucleophilic attack of the phosphine occurs at the activated C=C bond to form a zwitterionic monophosphonium species. With the phosphines PR3 [R = Me, Et, (CH2)3OH] and with R2R'P (R = Me or Et, R' = Ph), the zwitterion undergoes self-condensation to give a bisphosphonium zwitterion that can react with aqueous HCl to form the corresponding dichloride salts (as a mixture of R,R- and S,S-enantiomers); X-ray structures are presented for the bisphosphonium chlorides synthesized from the Et3P and Me3P reactions with sinapaldehyde.

Synthesis and X-ray structures of water-soluble tris(hydroxymethyl)phosphine complexes of rhodium(I).

The water-soluble Rh(I)-THP complexes: RhCl(1,5-cod)(THP) (), [Rh(1,5-cod)(THP)(2)]Cl (), RhCl(THP)(4) (), and trans-RhCl(CO)(THP)(2) () have been synthesized and characterized, where THP = P(CH(2)OH)(3); - are the first potentially useful entries into Rh(I)-THP chemistry, while and are the first structurally characterized Rh(I)-THP complexes.

Formation of a phosphine-phosphinite ligand in RhCl(PRR'2)[P,P-R'(R)POCH2P(CH2OH)2] and R'H from cis-RhCl(PRR'2)2[P(CH2OH)3] via P-C bond cleavage.

Reaction of RhCl(1,5-cod)(THP), where THP = P(CH(2)OH)(3), with several PRR'2 phosphines (R = or not equal R') generates, concomitantly with R'H, the derivatives RhCl(PRR'(2))[P,P-R'(R)POCH(2)P(CH(2)OH)(2)] in two isomeric forms. The hydrogen of the hydrocarbon co-product derives from a THP hydroxyl group which becomes an 'alkoxy' group at the residual PRR' moiety, this resulting in the P,P-chelated R'(R)POCH(2)P(CH(2)OH)(2) ligand. One of the isomers of the PPh(3) system, cis-RhCl(PPh(3))[P,P-P(Ph)(2)OCH(2)P(CH(2)OH)(2)], was structurally characterized (cis refers to the disposition of the P atoms with Ph substituents).

Chemistry and stereochemistry of the interaction of the water-soluble phosphine [HO(CH2)3]3P with cinnamaldehyde in aqueous media.

To learn more about the bleaching action of pulps by (hydroxymethyl)phosphines, cinnamaldehyde was reacted with tris(3-hydroxypropyl)phosphine, [HO(CH2)3]3P (THPP), in aqueous solution at room temperature under argon. Self-condensation of the aldehyde into two isomeric products, 2-benzyl-5-phenyl-pent-2,4-dienal and 5-phenyl-2-(phenylmethylene)-4-pentenal, is observed; this implies initial nucleophilic attack of the phosphine at the beta-carbon of the alpha,beta-unsaturated aldehyde. Reaction in D2O gives the same products in which all but the phenyl and CHO protons are replaced by deuterons.

trans-Carbonyl-chloridobis(ethyl-diphenyl-phosphine-κP)rhodium(I).

The title compound, [RhCl(C(14)H(15)P)(2)(CO)], crystallizes with two almost identical mol-ecules in the asymmetric unit. The mol-ecules have the Rh(I) atom in a square-planar geometry. The crystal structure involves intermolecular C-H⋯O hydrogen bonds.

Alpha-monodeuterated benzyl alcohols and phosphobetaines from reactions of aromatic aldehydes with a water/D2O-soluble phosphine.

With the aim of learning more about the bleaching action of pulps by (hydroxymethyl)phosphines, we reacted several benzaldehydes, containing MeO, Me, OH, or halogen substituents, with tris(3-hydroxypropyl)phosphine, [HO(CH2)3]3P, in aqueous solution at 90 degrees C under argon. Effective reduction of the aldehydes to the corresponding benzyl alcohols with concomitant oxidation of the phosphine to the phosphine oxide takes place, the reaction proceeding via an initially formed phosphonium species. When the reactions are carried out in D2O, the benzyl alcohol product from 3,4-dimethoxybenzaldehyde contains one deuterium atom at the benzyl-carbon atom, consistent with the last step of the mechanism involving a carbanion intermediate.

Ruthenium(III) maltolato-nitroimidazole complexes: synthesis and biological activity.

The Ru(III) metronidazole-maltolato and -ethylmaltolato complexes, trans-[RuL(2)(metro)(2)]CF(3)SO(3) (L=ma (1a) or etma (1b)), have been synthesized and tested for potential anti-tumour activity against the human breast cancer cell line MDA-MB-435S using a so-called MTT assay in phosphate-buffered saline; ma=3-hydroxy-2-methylpyran-4-onato, etma=2-ethyl-3-hydroxypyran-4-onato, metro=2-methyl-5-nitro-1H-imidazole-1-ethanol (metronidazole); MTT=3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. The complexes exhibit lower IC(50) values than our previously reported Ru(III) tris-maltolato and -ethylmaltolato complexes [D.C.

New oligophosphines and (hydroxymethyl)phosphonium chlorides.

The new oligophosphines [H2P(CH2)2]2PH, [H2P(CH2)2P(H)CH2]2, and{[(H2P(CH2)2]2PCH2}2 have been made by hydrophosphination of diethyl vinylphosphonate (2) with H2P(CH2)2PH2 (1), using different ratios of 2/1, followed by LiAlH4 reduction of the phosphonate intermediates; the three phosphonate precursors were obtained as oils of varying purity (approximately 90-95%) in low (approximately 20%) to almost quantitative yield. The tri-, tetra-, and hexaphosphines were then treated with formaldehyde in the presence of hydrochloric acid to generate the corresponding water-soluble (hydroxymethyl)phosphonium chlorides {(HOCH2)3P[(CH2)2P(CH2OH)2]n(CH2)2P(CH2OH)3}Cl m (n = 1, m = 3; n = 2, m = 4) and {[(HOCH2)3P(CH2)2]2P(CH2OH)CH2}2Cl6 that were characterized by NMR spectroscopy and elemental analysis. The known (hydroxymethyl)bisphosphonium chloride [(HOCH2)3P(CH2)2]2Cl2 was similarly prepared from H2P(CH2)2PH2, and the determined crystal structure revealed strong hydrogen bonding between the chloride anions and the hydrogen atoms of the hydroxymethyl groups.