Chlorobis(polyfluorophenyl)thallium(III) complexes and their reactions with gold(I) and tin(II) compounds

The reaction of TlCl₃ with RLi leads to complexes of the general formula TlR₂Cl (R = C₆F₅, p-C₆F₄H, m-C₆F₄H, 2,4,6-C₆F₃H₂, p-C₆FH₄ or m-CF₃C₆H₄). Some of these undergo oxidative addition reactions with gold(I) complexes to give polyfluorophenyl derivatives of the types AuR₂ClL and Au(C₆F₅)R₂(tht) (tht = tetrahydrothiophen), and with SnCl₂ to give oily materials from which stable solids of the general formula Q[SnR₂Cl₃] can be isolated by addition of QCl (Q = Et₄N or Ph₃BzP).     

Rhodium(I) complexes bound to silica via bidentate phosphine ligands

Triethoxysilyl substituted diphosphines of the novel type (EtO)₃Si(CH₂)_nP(Ph)CH₂CH₂PPh₂ (n=1, 3) have been prepared and used to immobilize rhodium(I) complexes to silica. The complexes were found to be effective catalysts for hydrogenation of 1,3-cyclooctadiene under mild conditions.

---

- (EtO)₃Si(CH₂)_nP(Ph)CH₂CH₂PPh₂ (n=1,3) SiO₂. 1,3- .

     

Rhodium(I) carbonyl complexes with sulphur and nitrogen donor ligands

Summary Rhodium(I) carbonyl complexes, namely [Rh(CO)₂ClL] where L = thiourea (Tu), 1,3-diphenyl-2-thiourea (DTu), dithizone (Dtz), indole (Id), 3-chloropyridine (Clpy), 3-hydroxypyridine (HOpy), 3-methylpyridine (Mepy), 2,5-dimethylpyridine (Me₂py) or 2,5-dichloropyridine (Cl₂py)] were prepared. [Rh(CO)₂Cl(Clpy)₂] has also been isolated. In the (Tu) complex, (C-S) occurs at ca. 710cm^-1, indicating the presence of a metal-sulphur bond. The carbonyl stretching frequencies in [Rh (CO)₂ClL] and [Rh(CO)₂CIL₂] occur at ca. 2100–1990 and 1830–1800 cm^-1, respectively. PPh₃ reacts with the complexes to form trans-[Rh(CO)Cl(PPh₃)₂]. The complexes were characterized by elemental analyses, conductivity measurements and by their i.r. spectra.     

Rhodium(I) phosphine complexes containing bidentate unsaturated thio ligands: II. Reactions with O2 and H2

The rhodium(I) complexes (Ph₃P)₂Rh[Me₂NC(S)NC(S)NMe₂], (Ph₃P)₂Rh[SC(S)NMe₂] and (Ph₃P)₂Rh[PhNC(S)NMe₂] react with O₂ to give 1/1 dioxygen adducts. In solution, trans-(Ph₃P)₂Rh(O₂)[Me₂NC(S)NC(S)NMe₂], cis- and trans-(Ph₃P)₂Rh(O₂)[SC(S)NMe₂] and cis- and trans-(Ph₃P)₂Rh(O₂)[PhNC(S)NMe₂] are observed. For (Ph₃P)₂Rh(O₂)[PhNC(S)NMe₂], there is a solvent effect on the initial cis—trans ratio and the rate of O=PPh₃ formation. In C₆H₆, O=PPh₃ formation from (Ph₃P)₂Rh(O₂)[PhNC(S)NMe₂] is inhibited by additional PPh₃.The reaction of (Ph₃P)₂Rh[Ph₂PC(S)NPh] with O₂ in the presence of additional PPh₃ gives O=PPh₃ and cis-(Ph₃P)₂Rh(O₂)[Ph₂P(O)C(S)NPh] as the only products. The same complex also can be prepared from (Ph₃P)₂Rh[Ph₂P(O)C(S)NPh] and O₂.Only (Ph₃P)₂Rh[PhNC(S)NMe₂] reacts with H₂ at room temperature to give (Ph₃P)₂RhH₂[PhNC(S)NMe₂], which is a catalyst for cyclohexene hydrogenation.     

Rhodium(I) phosphine complexes containing bidentate unsaturated thio ligands: I. Synthesis and characterisation

The rhodium(I) complexes (Ph₃P)₂Rh(LL′), in which LL′ is an unsaturated chelate coordinating via L = S and L′ = N, O, P or S, have been prepared from RhCl(PPh₃)₃ by two routes.Direct substitution of one Ph₃P and Cl^? by the chelate anion gives (Ph₃P)₂Rh[Ph₂PC(S)S] (L = S, L′ = P). Oxidative addition of an NH bond followed by reductive elimination of HCl results in (Ph₃P)₂Rh[Me₂NC(S)NC(S)NMe₂] (L = S, L′ = S), (Ph₃P)₂Rh[PhNC(S)NMe₂] (L = S, L′ = N), (Ph₃P)₂Rh[Ph₂PC(S)NPh) (L = S, L′ = P) and (Ph₃P)₂Rh[Ph₂P(O)C(S)NPh] (L = S, L′ = O).Reaction of the complexes (Ph₃P)₂Rh(LL′) with CO gives (CO)(Ph₃P)Rh(LL′) with CO trans to the chelate donor atom with the lowest trans-influence. Pt(PPh₃)₄ reacts with Me₂NC(S)N(H)C(S)NMe₂ and HN(Ph)C(S)PPh₂, respectively, to give H(Ph₃P)Pt[Me₂NC(S)NC(S)NMe₂] (L = S, L′ = S) and H(Ph₃P)Pt[Ph₂PC(S)NPh] (L = S, L′ = P).The coordinating atoms and their configurations have been assigned by IR ³¹P NMR and ¹H NMR. Some trend in IR and ³¹P NMR paramaters are discussed.     

Achiral banana-shaped mesogenic bidentate ligands and their Cu(II) and Pd(II) complexes

The first achiral bent-core banana-shaped bidentate ligands and their Cu(II) and Pd(II) metal complexes have been synthesized and investigated for mesomorphic behaviour. The bidentate ligands exhibit only one enantiotropic mesophase. The ligand having C 6 -alkoxy chains shows a mesophase that has been assigned as a two-dimensional B 1 phase while the C 8 and C 10 homologues stabilize the fluid B 2 mesophase showing antiferroelectric switching characteristics. In constrast, their corresponding Cu(II) and Pd(II) metal complexes are non-mesomorphic.     

Achiral banana-shaped mesogenic bidentate ligands and their Cu(II) and Pd(II) complexes

The first achiral bent-core banana-shaped bidentate ligands and their Cu(II) and Pd(II) metal complexes have been synthesized and investigated for mesomorphic behaviour. The bidentate ligands exhibit only one enantiotropic mesophase. The ligand having C6 -alkoxy chains shows a mesophase that has been assigned as a two-dimensional B1 phase while the C8 and C10 homologues stabilize the fluid B2 mesophase showing antiferroelectric switching characteristics. In constrast, their corresponding Cu(II) and Pd(II) metal complexes are non-mesomorphic.     

Isolation of [Rh(diolefin)X2]- species and their reactions with P- or N-donor ligands,tin(II) halides and carbon monoxide

Anionic [Rh(diolefin)X₂]⁻ species (X = Cl, Br) have been prepared and their reactions studied. The reactions with monodentate ligands led to neutral tetracoordinated complexes, and with N-donor bidentate ligands (Rh : LL = 2 : 1) gave Rh(X)(diolefin)(LL), [Rh(diolefin)(LL)]⁺[Rh(diolefin)X₂]⁻, or [Rh(diolefin)(LL)]X compounds, depending on the nature of LL or X. Reactions with carbon monoxide involved diolefin displacement. A trichlorostannato complex was obtained from the [Rh(COD)Cl₂]⁻ species. Reactions of [Rh(COD)Br]₂ with bidentate N-donor ligands were also studied.     

Novel chiral dimesogenic bidentate ligands and their Cu(II) and Pd(II) metal complexes

The synthesis and characterization of cholesterol-based dimesogenic bidentate ligands and their Cu(II) and Pd(II) metallomesogens are reported in detail. To understand structure-property relationships in these materials the terminal alkoxy chains and the central metal atom have been varied. Our studies reveal that chiral dimesogenic bidentate ligands with n -butyloxy chains exhibit smectic A (SmA), twist grain boundary and chiral nematic (N * ) mesophases while substitution with either n -decyloxy or 3,7-dimethyloctyloxy chains also show a ferroelectrically switchable chiral smectic C (SmC * ) mesophase. The metal complexes with n -butyloxy chains show only the SmA phase whereas higher chain length derivatives exhibit N * phase irrespective of the metal atom present. The ligands are thermally stable whereas their metal complexes, especially Pd(II) systems, seem to be heat sensitive. Spontaneous polarization, response time and tilt angle measurements have been carried out in the smectic C * phase of the two ligands.     

Ruthenium(II) complexes containing bidentate Schiff bases and their antifungal activity

The reactions of ruthenium(II) complexes, [RuHCl(CO)(PPh₃)₂(B)] [B = PPh₃, pyridine (py) or piperidine (pip)], with bidentate Schiff base ligands derived by condensing salicylaldehyde with aniline, o-, m- or p-toluidine have been carried out. The products were characterised by analytical, i.r., electronic, ¹H-n.m.r. and ³¹P-n.m.r. spectral studies and are formulated as [RuCl(CO)(L)(PPh₃)(B)] (L = Schiff base anion; B = PPh₃, py or pip). An octahedral structure has been tentatively proposed for the new complexes. The Schiff bases and the new complexes were tested in vitro to evaluate their activity against the fungus Aspergillus flavus.     

Novel chiral dimesogenic bidentate ligands and their Cu(II) and Pd(II) metal complexes

The synthesis and characterization of cholesterol-based dimesogenic bidentate ligands and their Cu(II) and Pd(II) metallomesogens are reported in detail. To understand structure-property relationships in these materials the terminal alkoxy chains and the central metal atom have been varied. Our studies reveal that chiral dimesogenic bidentate ligands with n-butyloxy chains exhibit smectic A (SmA), twist grain boundary and chiral nematic (N*) mesophases while substitution with either n -decyloxy or 3,7-dimethyloctyloxy chains also show a ferroelectrically switchable chiral smectic C (SmC*) mesophase. The metal complexes with n-butyloxy chains show only the SmA phase whereas higher chain length derivatives exhibit N* phase irrespective of the metal atom present. The ligands are thermally stable whereas their metal complexes, especially Pd(II) systems, seem to be heat sensitive. Spontaneous polarization, response time and tilt angle measurements have been carried out in the smectic C* phase of the two ligands.     

Rhodium(I) indazole and indazolate complexes

The preparation of cationic indazole (HIdz) rhodium(I) complexes of the types [(diolefin)Rh(HIdz)₂]ClO₄ and [(CO)₂Rh(HIdz)₂]ClO₄ is described. Neutral binuclear rhodium(I) complexes of the type [Y₂Rh(μ-Idz)]₂ (Y₂  COD, TFB, NBD, (CO)₂ or (CO)(PPh₃)) are obtained by treating the corresponding complexes [Y₂RhCl]₂ with indazole and organic or inorganic bases. The cationic mononuclear derivatives react with the solvated species [Y₂Rh(acetone)_x]ClO₄ in the presence of triethylamine to give neutral binuclear complexes of the types [(CO)₂Rh(μ-Idz)₂Rh(diolefin)], [(Ph₃P)(CO)Rh(μ-Idz)₂Rh(diolefin)] and [(diolefin)Rh(μ-Idz)Rh(diolefin′)] (diolefin  COD, TFB or NBD; diolefin′  COD or TFB). Alternative methods for the synthesis of the binuclear complexes are also described.     

Studies of the reactions of platinum halo complexes with tin(II) halides

The reaction of a dichloromethane solution of a mixture of cis,trans-[PtCl₂(SMe₂)₂] with a tetrahydrofuran solution of SnBr₂ resulted in oxidation of platinum(II) with halogen exchange producing cis,trans-[PtBr₄(SMe₂)₂]. Reaction of a mixture of cis,trans-[PtCl₂(SEt₂)₂], potassium tetrachloroplatinate(II) or potassium hexachloroplatinate(IV) with SnBr₂ in hydrochloric acid solution resulted in formation of predominantly anionic five-coordinate trichlorostannyl platinum(II) complexes. Reaction of potassium tetrabromoplatinate(II) with SnCl₂ in hydrobromic acid in the presence of tetraphenylphosphonium bromide affords cis-[PPh₄]₂[PtBr₂(SnBr₃)₂]. The insertion of SnCl₂ into Pt–Cl bond of platinum(II) complexes cis-[PtCl₂(L₂)] {L₂ = (PPh₃)₂; (PMe₃)₂; {P(OMe)₃}₂; dppm (bis(diphenylphosphino)methane); dppa (bis(diphenylphosphino)amine); and dppe (1,2-bis(diphenylphosphino)ethane)} is described.     

Octahedral ruthenium (II) carbonyl complexes with nitrogen,sulphur and tin donor ligands

The reaction of a carbonyl-containing ruthenium solution with amines leads to isolation of the amino-carbonyl complexes: [Ru(C₆H₅NH₂)₂(CO)₂X₂], [Ru(C₆H₅CH₂NH₂)₂(CO)₂X₂], [Ru(phen)(CO)₂X₂] ( X = Cl, Br), [Ru(dipy)(CO)₂Cl₂] and [Ru{C₆H₄(S)NH₂}(CO)₂]. Preparation of the trihalostannato-carbonyl complexes [Ru(py)₂(CO)₂(SnX₃)₂] (X = Cl, Br), and [Ru(Et₂S)₃ (CO)₂SnCl₃]X (X = Cl, Ph₄B) via the carbonyl-containing solution is also prepared.     

Rhodium(III)-catalyzed oxidative carbonylation of benzamides with carbon monoxide

An efficient strategy for the oxidative carbonylation of aromatic amides via C-H/N-H activation to form phthalimides using an Rh(III) catalyst has been developed. The reaction shows a preference for C-H bonds of electron-rich aromatic amides and tolerates a variety of functional groups.     

Rhodium(I) carbonyl complexes of triphenylphosphine chalcogenides and their catalytic activity

Rhodium(I) carbonyl complexes [Rh(CO)₂ClL] where L = Ph₃PO, Ph₃PS and Ph₃PSe, were synthesized and characterized by elemental analysis, i.r. and by ¹H-, ¹³C- and ³¹P-n.m.r. spectroscopy. The vBD;(CO) band frequencies in the complexes follow the order: Ph₃PO > Ph₃PS > Ph₃PSe, in keeping with the hard/soft nature of the interactions. The complexes undergo oxidative additions with electrophiles such as MeI, PhCH₂Cl and I₂ to give, e.g. [Rh(CO)(COMe)ClIL] which react with PPh₃ to give trans-[Rh(CO)Cl(PPh₃)₂]. The catalytic activity of the [Rh(CO)₂ClL] complexes in carbonylation of MeOH is higher than that of the well-known [Rh(CO)₂I₂]⁻ species. This revised version was published online in June 2006 with corrections to the Cover Date.     

Rhodium(III) complexes with a bidentate N-heterocyclic carbene ligand bearing flexible dendritic frameworks

Rh(III) complexes with a bidentate N-heterocyclic carbene ligand bearing flexible dendritic frameworks have been synthesized and fully characterized by X-ray crystallographic analysis, NMR measurements and theoretical calculations.