Cyanide Ligands Research Articles

Synthesis and characterization of a monocyanide-bridged bimetallic iron(II) and copper(I) complex.

An equilibrium is established between CpFe(CO)2CN and Cu(CH3CN)4+ in acetonitrile and adduct formation between the cyanide ligand and copper(I), whereas, complete complexation is observed in methylene chloride. Derivatization of the adduct in methylene chloride with PCy3 led to the isolation of the [CpFe(CO)2(μ-CN)Cu(PCy3)2][BF4] salt, which has been characterized by X-ray crystallography.

Derivatives of the [Ru(bipy)(CN)4]2– chromophore with pendant pyridyl-based binding sites: synthesis, pH dependent-luminescence, and time-resolved infrared spectroscopic studies

Reaction of K4[Ru(CN)6] with 2,2′:4′,4″-terpyridine (L1) or 2,2′:3′,2″:6″,2‴-quaterpyridine (L2) in acidic aqueous methanol affords the complexes K2[Ru(L1)(CN)4] and K2[Ru(L2)(CN)4] respectively, both containing the {Ru(bipy)(CN)4}2− chromophore but with pendant pyridyl or bipyridyl units, respectively. Time-resolved IR analysis of K2[Ru(CN)4(L2)] in MeCN–D2O showed that the most intense CN stretching vibration shifted to higher energy by ca. 50 cm−1 after laser excitation, consistent with formation of a Ru(III)/(L2)˙− MLCT excited state for which the lifetime measurement (38 ± 5 ns, measured by TRIR) agrees reasonably well with the value measured by luminescence methods (30 ± 2 ns). Study of the pH dependence of the absorption and emission spectra of the two complexes revealed the presence of two different effects arising from protonation of the pendant pyridyl/bipyridyl site (which occurs with pKa ≊ 3.1 in each case) and protonation of the cyanide ligands (which occurs with pKa ≊ 2 in each case). For K2[Ru(L1)(CN)4], protonation of the pendant pyridyl unit results in the 1MLCT excited state being lowered in energy by ca. 1000 cm−1, whereas at lower pH values (2.5–1), protonation of the cyanide ligands raises the 1MLCT excited state energy by over 2000 cm−1. For K2[Ru(L2)(CN)4] in contrast, protonation of the pendant bipyridyl unit has no detectable effect on the 1MLCT energy, as the pendant site is electronically decoupled from the complex core by a substantial twist between the free and coordinated bipy components of L2; protonation of the cyanides at lower pH values however destabilises the 1MLCT excited state. Protonation of the pendant pyridyl sites results in complete (for [Ru(L1)(CN)4]2−) or near-complete (for [Ru(L2)(CN)4]2−) quenching of the luminescence; possible reasons for this behaviour are discussed. The crystal structures of the two related complexes [Ru(tBu2bipy)2(L1)][PF6]2 and [Cl2Pt(μ-L2)Ru(bipy)2][PF6]2 are also described to illustrate arguments about the conformations of L1 and L2.

Acid Catalyzed Dissociation of 4‐Aminopyridine Complex of Pentacyanoferrate (II)

AbstractFe(CN)5ampy3− (ampy = 4‐aminopyridine) complex was unstable at pH ≤ 4 with respect to the dissociation due to the protonations of the complex. The first protonation on the 4‐aminopyridine ligand at pKa = 3.2 resulted in a ≅ 150‐fold in crease in rate of dissociation as compared to that of the complex in the neutral solution. However, further protonation of the complex on the cyanide ligand at pKa = 1.5 in creased the rate only slightly. The large in crease in the rate constant of dissociation for Fe(CN)5ampyH2− complex suggests that in the transition state the proton is likely shifted from the amino group and becomes coordinated to a pair of dπ electrons directed at the face of the coordinated octahedron.

Probing hydrogen bond network formation in anion–water clusters through high energy collision experiments

In high-energy collisions (50 keV in the laboratory system) between anion–water clusters [X−⋅(H2O)n, X−=Cl−, CN−, O2−, NO2−, NO3−; n=1–6] and argon, H3O+ is formed with an abundance that is determined by the cluster size—the larger the cluster, the more H3O+. The mechanism for H3O+ formation is believed to be a nearly vertical ionization process (two-electron stripping) followed by an exothermic intracluster hydrogen transfer reaction between an ionized water and a neutral water. The abundance of H3O+ can be used as a probe to determine how extended the water hydrogen bond network is in the initial anion–water cluster and to distinguish between surface solvation (water network preserved) and internal solvation (water network broken). In this work, it is demonstrated that in the hydration of hexacyanoplatinate(IV) dianion complexes, surface solvation is important despite the large number of available water binding sites; however, the competition between a cyanide-bound water and a “naked” cyanide ligand for a water molecule favors the cyanide-bound water because of the splitting of the excess charges between six ligands (between −1/3 and −1 charge at each ligand on average). We also investigate anion–methanol clusters in which the hydrogen bond network is less extended with the result of a less abundant oxonium ion compared to the hydronium ion from similar size water clusters.

Isolation and spectroscopic characterization of a recombinant bell pepper hydroperoxide lyase

Fatty acid hydroperoxide (HPO) lyase is a component of the oxylipin pathway and holds a central role in elicited plant defense. HPO lyase from bell pepper has been identified as a heme protein which shares 40% homology with allene oxide synthase, a cytochrome P450 (CYP74A). HPO lyase of immature bell pepper fruits was expressed in Escherichia coli and the enzyme was purified and characterized by spectroscopic techniques. The electronic structure and ligand coordination properties of the heme were investigated by using a series of exogenous ligands. The various complexes were characterized by using UV-visible absorption and electron paramagnetic resonance spectroscopy. The spectroscopic data demonstrated that the isolated recombinant HPO lyase has a pentacoordinate, high-spin heme with thiolate ligation. Addition of the neutral ligand imidazole or the anionic ligand cyanide results in the formation of hexacoordinate adducts that retain thiolate ligation. The striking similarities between both the ferric and ferrous HPO lyase–NO complexes with the analogous P450 complexes, suggest that the active sites of HPO lyase and P450 share common structural features.

Synthesis of new donor/acceptor η 5-cyclopentadienyl and η 5-indenyliron(II) complexes with p-benzonitrile derivatives. Crystal structures of [Fe(η 5-C 5H 5)(CO)(P(OC 6H 5) 3)( p-NCC 6H 4NO 2)][BF 4]·CH 2Cl 2 and [Fe(η 5-C 9H 7)(CO)(P(OC 6H 5) 3)( p-NCC 6H 4NO 2)][BF 4

New complexes of the type [Fe(η 5-Cp or Ind)(L)(L′)( p-NCR)][BF 4] (L, L′=CO, P(OC 6H 5) 3, P(C 6H 5) 3; R=C 6H 4N(CH 3) 2, C 6H 4NO 2, ( E)-C(H)C(H)C 6H 4NO 2, ( E)-C(H)C(H)C 6H 4N(CH 3) 2) have been synthesised and characterised. Spectroscopic data were analysed in order to evaluate the tuning of the electronic density at the metal centre and the extension of the π-delocalisation on the molecule, due to the presence of coligands with different acceptor/donor abilities. The structures of two complexes [Fe(η 5-C 5H 5)(CO)(P(OC 6H 5) 3)( p-NCC 6H 4NO 2)][BF 4] and [Fe(η 5-C 9H 7)(CO)(P(OC 6H 5) 3)( p-NCC 6H 4NO 2)][BF 4] were determined by X-ray crystallographic analysis. The compounds crystallised in the centrosymmetric space groups P1̄ and P2 1/ n, respectively. Bond distances within the nitrile ligand are discussed in order to evaluate the nature of iron–nitrile bonding in these complexes.

CRYSTAL STRUCTURE AND MAGNETIC MEASUREMENTS OF CIS-DICYANO-BIS (1,10-PHENANTHROLINE)IRON(III) SULFATE

The structure of the solvatochromic complex cis-dicyano-bis(1,10-phenanthroline)iron(III) sulfate dihydrate was determined by X-ray diffraction. The complex crystallized in a compressed octahedral conformation with the cyanide ligands cis-bonded. The unit cell contains enantiomeric pairs of the compound with a network of sulfate ions and water molecules stabilized by hydrogen bonding. The magnetic moments of the perchlorate salt dissolved in both water and nonaqueous solvents were probed and found to be in accord with a solvated, low spin [Fe(III)(phen)2(CN)2]+ ion, (μexp = 2.0–2.6 BM, 298K), showing no dependence on the empirical solvent parameters AN, DN, ET(30) and π*.

Extremely bent cyanide coordination at a preorganized dinickel site and assembly of a starlike nonanuclear complex from the constrained dinickel building blocks.

An extremely bent cyanide coordination at a dinickel scaffold is reported. Preorganization of two nickel ions is achieved by means of a compartmental dinucleating pyrazolate ligand L(-), setting up a bimetallic coordination pocket with constrained metal-metal separation. The mixed-spin dinickel(II) complex [LNi2(CN)(MeCN)](ClO4)2 (1) has been characterized by X-ray diffraction. The MeCN bound to the high-spin nickel(II) ion can be removed or replaced by other ligands, e.g., by the cyanide ligand of a tetracyanonickelate(II) moiety to give the starlike nonanuclear complex ([LNi2(CN)]4[Ni(CN)4])(ClO4)6 (2) that contains four of the constrained pyrazolate-based dinickel(II) fragments grouped around a central tetracyanonickelate(II) unit, as revealed by X-ray crystallography. Spectral and electrochemical properties of 1 and 2 are reported, and the formation of reduced mixed-valent Ni(I)Ni(II) species is investigated by IR and UV/vis spectroelectrochemistry.

Syntheses and structural characterizations of sheet- and column-like lanthanide-transition metal arrays: the effect of hydrogen bonding on the structure when K(+) is replaced by [NH4]+.

Sheet- and column-like cyanide bridged lanthanide-transition metal arrays were synthesized through metathesis reactions between anhydrous LnCl(3) (Ln = Eu, Yb) and A(2)[M(CN)(4)] (A = K(+), NH(4)(+); M = Ni, Pt) in a 1:2 molar ratio in DMF (DMF = N,N-dimethylformamide) solution. Single-crystal X-ray analysis revealed that complexes of formula [K(DMF)(7)Ln[M(CN)(4)](2)](infinity) (Ln = Eu, M = Ni, 1; Ln = Yb, M = Pt, 2) consist of infinite layers of neutral, puckered sheets that contain hexagonal rings of composition [(DMF)(10)Ln(2)[M(CN)(4)](3)](6) with interstitial (DMF)(4)K(2)[M(CN)(4)] units located between the layers. The sheet structure is generated through the repeating (DMF)(10)Ln(2)[M(CN)(4)](3) unit with trans cyanide ligands in [M(CN)(4)](2)(-) serving as bridges. The column-like complex [(NH(4))(DMF)(4)Yb[Pt(CN)(4)](2)](infinity), 3, is formed when NH(4)(+) replaces K(+). It consists of infinite, negatively charged, square, parallel columns bundled through N-H...NC hydrogen bonds between NH(4)(+) and terminal CN from the columns. Cis cyanide ligands in [Pt(CN)(4)](2)(-) units serve as bridges. Complex 3 is the first known example where Ln(III) centers are coordinated to four [M(CN)(4)](2)(-) units. Bicapped (square face) trigonal prismatic coordination geometries were observed for Ln(III) centers in 1 and 2. Square antiprismatic geometry for Yb(III) centers are observed in 3. Crystal data for 1: triclinic space group P1, a = 8.797(2) A, b = 15.621(3) A, c = 17.973(6) A, alpha = 105.48(2) degrees, beta = 98.60(2) degrees, gamma = 98.15(2) degrees, Z = 2. Crystal data for 2: triclinic space group P1, a = 8.825(1) A, b = 15.673(1) A, c = 17.946(1) A, alpha = 105.46(2) degrees, beta = 99.10(1) degrees, gamma = 98.59(1) degrees, Z = 2. Crystal data for 3: monoclinic space group P2(1)/c, a = 9.032(1) A, b = 29.062(1) A, c = 15.316(1) A, beta = 94.51(1) degrees, Z = 2.

Cyanide Exchange on Tl(CN)4− in Aqueous Solution Studied by205Tl and13C NMR Spectroscopy

Dynamics of cyanide exchange between Tl((CN)-C-13)(4)(-) and (CN-)-C-13 was studied by means Tl-205 and C-13 NMR. The rate law consists of two parts: w = k(CN)[Tl(CN)(4)(-)][CN-] + k(OH)[Tl(CN)(4)(-)][CN-][OH-] with k(CN) = 9.7(+/-0.4) x 10(6) M(-1)s(-1) and k(OH) = 5.4(+/-0.4) x 10(10) M(-2)s(-1). It was shown that the exchange between the two cyano species can be studied, not only by C-13 NMR, but also by Tl-205 NMR using the heteronuclear carbon-thallium scalar coupling as an indicator, despite the fact that only one Tl site is present in the system. The reaction mechanism is discussed in terms of an associative interchange mechanism, I-A. Penetration of the incoming cyanide ion into the coordination sphere of Tl(CN)(4)(-) Tl(CN)(4)(OH)(-) is suggested to be the rate-determining step for the two parallel reactions paths. Possible reasons for the strong labilizing effect of the cyanide ligand is discussed in the light of thermodynamic and structural data. The possibility of detection of an exceptional exchange reaction, namely cyanide exchange between two Tl(CN)(4)(-) entities by a direct encounter was theoretically settled, but found to be too slow to be detected.

Structure, solvation, and bonding in pentacyano(L)ferrate(II) ions (L=aliphatic amine): a density functional study

Quantum chemical calculations using density functional theory have been carried out to investigate the influence of aqueous solvation on the structure and bonding in [Fe(CN)5L]3–with L an aliphatic amine (ammonia, methylamine, hydrazine, and ethylenediamine). Gas phase equilibrium geometries were fully optimized at the generalized gradient approximation (GGA) level. Solvent effects were modeled within the DFT methodology by using a discrete electrostatic representation of the water molecules in the first solvation shell. For the hydrazine and ethylenediamine complexes in vacuum we found two internal hydrogen bonds between the terminal amino group hydrogens and two equatorial cyanide ligands. However, considering the first solvation shell, an open structure in which the terminal amino group is solvated by water molecules becomes more stable in the ethylenediamine case. Metal–L dissociation energies were computed in vacuum, taking the first solvation shell into account. The results obtained were compared with experimental kinetic data in aqueous solution in order to assess the role of solvation in the reactivity of these complexes.

Photosensitivity of Aqueous Sodium Nitroprusside Solutions: Nitric Oxide Release versus Cyanide Toxicity

Photolysis of the pentacyanonitrosylferrate (II) ion in sodium nitroprusside (SNP) solutions involves a competition between photosubstitution and photo-oxidation reactions, where the nitrosyl and cyanide ligands can be released as free nitric oxide (NO) or NO+ and free CN- or CN radical. We have irradiated aqueous SNP solutions at several narrow wavelength ranges in the UV/Vis region (314–576 nm), with the aim of investigating the photolability of the CN and NO ligands. Kinetics of photolysis were used to characterize the photosensitivity of SNP solutions in the range 314–576 nm. Spectral changes in the UV/Vis and IR regions upon irradiation and assays for the detection of free CN- and NO, provided additional evidences for the absence of photoprocesses leading to the release of CN- with λirr > 480 nm. In this condition, the main photoproducts were found to be the [FeIII(CN)5(H2O)]2- ion and NO, formed in a intramolecular photo-oxidative process. Irradiation with unfiltered UV/Vis light and with λirr < 480 nm, lead to the release of both CN- and NO and to a mixture of ferrocyanide and ferricyanide products. These results confirm that the exposure of SNP solutions to UV/Vis light below λirr = 480 nm can lead to cyanide poisoning and further support that above this wavelength limit, a selective NO release from SNP can be achieved, with possible implications for its biochemical action.

A New Two‐dimensional Cyano‐bridged Chromium (HI)‐Nickel (II) Bimetallic Assembly with Stair‐like Layers

AbstractFrom the reaction of K3[Cr(CN)6] and [NiL](CIO4)2 (L= 1,8‐di(hydroxyethyl)‐l, 3, 6, 8, 10, 13‐hexaazacyclotetradecane), an infinite stair‐like layered assembly [NiL]3 [Cr‐(CN)6]2‐6.5H2O is obtained, in which each hexacyanochromate(III) ion connects three nickel(II) ions using three cis Of groups and the bridging cyanide ligands coordinate to the nickel ion in a trans fashion forming trans‐NiL(N°C)2 moieties.

Some New Dicationic Dihydrogen Complexes of Ruthenium

A series of new dicationic dihydrogen complexes of ruthenium of the type trans-[(dppe)2Ru(η2-H2)(RCN)][BF4]2 [dppe = Ph2PCH2CH2PPh2; R = CH3, CH3CH2, CH3CH2CH2, CH2=CH, p-CH3−C6H4−CH2, C6H5, and (CH3)2N] have been prepared by the protonation reaction of the precursor hydrides, trans-[(dppe)2Ru(H)(RCN)][BF4] using HBF4·OEt2. The variable temperature spin-lattice relaxation times (T1, ms) and the H, D coupling constants of the η2-HD isotopomers indicate the intact nature of the H−H bond in these complexes. It was found that the spectroscopic and chemical properties of these derivatives are not very sensitive to the change in the trans nitrile ligand. The pKa values of the dihydrogen complexes have been determined using the equilibrium: trans-[(dppe)2Ru(H)(RCN)][BF4] + HBF4·OEt2 ⇄ trans-[(dppe)2Ru(η2-H2)(RCN)][BF4]2 + Et2O by 1H NMR spectroscopy.

Designer magnets containing cyanides and nitriles.

Magnets synthesized from molecules have contributed to the renaissance in the study of magnetic materials. Three-dimensional network solids exhibiting magnetic ordering have been made from several first-row metal ions and bridging unsaturated cyanide, tricyanomethanide, and/or dicyanamide ligands. These materials possess several different structural motifs, and the shorter the bridge, the stronger the interaction (i.e., -Ctriple bondN- > -Ntriple bondC-N- >> Ntriple bondC-N-Ctriple bondN- = Ntriple bondC-C-Ctriple bondN-). Cyanide additionally has the ability to discriminate between C- and N-bonding to form ordered heterobimetallic magnets, and the strong coupling can lead to ferro- or ferrimagnetic ordering substantially above room temperature. Tricoordination of tricyanomethanide results in spin-frustrated systems, which possess interpenetrating rutile-like networks. In contrast, single rutile-like frameworks are formed by mu(3)-bonded dicyanamide, which leads to ferromagnetics and weak ferromagnetics.

New approaches to magnetic clusters with hexacyanometallate building blocks

Polymeric cyanide complexes, whose archetype is the well-known Prussian blue mixed valence compound Fe 4[Fe(CN) 6] 3, are key players in the field of molecule-based magnetism. One reason for the popularity of the cyanide ligand is that it effects strong and predictable magnetic exchange interactions between paramagnetic centers. In an effort to produce high-dimensional materials that behave as magnets, researchers in the area have focused on reactions of [M(CN) 6] n− with labile cations that contain few or no protecting groups to limit the growth of polymeric phases. This article reports the syntheses and characterization of new ligand protected precursors of the types cis-[M(LL) 2(S) 2] 2+ (S=solvent), cis-M(LL) 2(CN) 2 and cis-M(LL) 2(O 35CF 3) 2. Reactions of these convergent precursors with hexacyanometallate anions yield novel cyanide clusters, described along with key X-ray structures.

Purification and characterization of a novel bromoperoxidase-catalase isolated from bacteria found in recycled pulp white water

A bacterial strain, Pseudomonad EF group 70B, containing a high catalase-like activity was found in process water (white water) from pulp using recycled fibers. The enzyme was purified and characterized, and found to be a hydroperoxidase. The active enzyme has an apparent molecular mass of about 153 kDa with two identical subunits and a pI value of 4.7. It has a rather sharp pH optimum for catalase activity at 6.0 but exhibits catalase, peroxidase and brominating activities over a broad pH range from 4 to 8. It was not inhibited by 3-amino-1,2,4-triazole. Peroxidase-like activity was found when adding o-dianisidine, pyrogallol, guaiacol and 4-aminoantipyrine. Brominating activity was noticed using monochlorodimedone as a substrate. The absorption spectrum exhibited a Soret band at 404 nm. Upon reduction with dithionite the Soret peak decreased and shifted to 436 nm. Pyridine hemochrome spectra indicated the presence of a protophorfyrin IX heme group and the enzyme was inhibited by the known heme ligands cyanide and azide. N-terminal amino acid analysis gave the sequence STEVKLPYAVAGGGTTILDAFPGE, which showed no homology with those of known catalases or peroxidases. It is concluded that the enzyme is a novel type of catalase-peroxidase or, more specifically, a bromoperoxidase-catalase, and that future developments of inhibitors of hydrogen peroxide-degrading activities in white water may be based on this enzyme and other catalase-peroxidases.

Synthesis, Crystal Structure and Magnetic Properties of Novel Complex [μ-(NC)-Fe(CN)3(NO)-μ-(CN)-Cu(ept)]n·4nH2O (ept = N-(2-Aminoethyl)propane-1,3-diamine)

The novel complex [μ-(NC)-Fe(CN)3(NO)-μ-(CN)-Cu(ept)]n·4nH2O (ept = N-(2-aminoethyl)- propane-1,3-diamine) was obtained by the reaction of Cu(ClO4)2·6H2O with N-(2-amino- ethyl)propane-1,3-diamine and Na2[Fe(CN)5NO]·2H2O in water. This compound was characterized by IR, UV-VIS and EPR spectroscopies and magnetic measurement. Single-crystal X-ray structure analysis revealed that the title complex has a one-dimensional polymeric structure containing hexacoordinate iron(II) with five cyanide ligands (two of them, in trans position, bridging) and one nitrosyl group, and pentacoordinate copper(II) with N-(2-aminoethyl)propane-1,3-diamine and two sites occupied by bridging cyanide ligands. Magnetic investigation revealed a very weak antiferromagnetic interaction between the copper atoms (superexchange interaction parameter J = -1.7(1) cm-1; H = -JSiSi+1) within the chain through the diamagnetic [Fe(CN)5NO]2- ions.

Organometallic complexes for second-order non-linear optics: synthesis and molecular quadratic hyperpolarizabilities of η 5-monocyclopentadienyliron(II) nitrile derivatives with different phosphines. X-ray crystal structure of [FeCp(DPPE)( p-NCC 6H 4NO 2)][PF 6]·CH 2Cl 2

New complexes of the type [FeCp(P_P)( p-NCR)][PF 6] (P_P=( S)-PROLOPHOS, DPPE and ( R)-PROPHOS (( S)-PROLOPHOS=( S)- N-(diphenylphosphino)-2-diphenylphosphinooxymethylpyrrolidine; DPPE=1,2-bis(diphenylphosphino)ethane; ( R)-PROPHOS=( R)-(+)-1,2-bis(diphenylphosphino)propane); R=C 6H 4N(CH 3) 2, C 6H 4NO 2, ( E)-C(H)C(H)C 6H 4NO 2, C 6H 4C 6H 4NO 2) have been synthesized and characterized. Spectroscopic data were evaluated in order to correlate the tuning of the electronic density at the metal center with the first molecular hyperpolarizabilities ( β) determined by hyper-Rayleigh scattering at 1064 nm. Experimental β values increase with chain length and with the enhancement of the donor ability of the bidentate phosphine. [FeCp(DPPE)(( E)- p-NCC(H)C(H)C 6H 4NO 2)][PF 6] is found to have the highest β value (570×10 −30 esu) in the series. Molecular orbital calculations were carried out to understand the geometric and electronic factors involved and also to compute the static hyperpolarizabilities, β 0. These results are consistent with the trend observed in the β 0 values derived from experiment on the basis of the two-level model. The complex [FeCp(DPPE)( p-NCC 6H 4NO 2)][PF 6] was crystallographically characterized. The compound crystallizes in the centrosymmetric space group Pbcn. Bond distances within the nitrile ligand were discussed in order to evaluate the extension of π-backdonation suggested by spectroscopic data.

Synthesis and characterisation of a RuII([14]aneS4) complex immobilised in MCM-41-type mesoporous silica

Ruthenium(II) complexes containing the macrocycle 1,4,8,11-tetrathiacyclotetradecane ([14]aneS4) and nitrogen-coordinated nitrile ligands were prepared using cis-[Ru(DMSO)4Cl2] as the starting material. The first synthetic step consisted of introduction of the thioether ligand to give [Ru([14]aneS4)(DMSO)Cl]Cl. Substitution of the DMSO ligand by the nitrile ligands NCCH3 or NC(CH2)3Si(OEt)3 (L) gave the complexes [Ru([14]aneS4)(L)Cl]X (X = Cl−, PF6−). Introduction of the triethoxysilyl ligand allowed the [Ru([14]aneS4)Cl]+ fragment to be tethered to the surface of the ordered mesoporous silica MCM-41 by pore volume impregnation of a solution of the complex in dichloromethane. A high metal loading was achieved (0.56 mmol g−1). Powder XRD and N2 adsorption studies of the derivatised material indicated that the textural properties of the support were preserved during the grafting experiment and that the channels remained accessible, despite a large reduction in both surface area and pore volume (ca. 50%). IR, UV/VIS, photoluminescence and MAS NMR spectroscopy (13C, 29Si) confirmed that the structural integrity of the RuII complex was retained during immobilisation, except for loss of ethoxide groups due to the reaction with pendant silanols on the silica surface.