Copper(II), cobalt(II), and nickel(II) complexes with a bulky anthracene-based carboxylic ligand: syntheses, crystal structures, and magnetic properties

To systematically explore the influence of the bulky aromatic ring skeleton with a large conjugated pi-system on the structures and properties of their complexes, six CuII, CoII, and NiII complexes with the anthracene-based carboxylic ligand anthracene-9-carboxylic acid (HL1), were synthesized and characterized, sometimes incorporating different auxiliary ligands: [Cu2(L1)4(CH3OH)2](CH3OH) (1), [Cu4(L1)6(L2)4](NO3)2(H2O)2 (2), {[Cu2(L1)4(L3)](CH3OH)0.25}infinity (3), [Co2(L1)4(L4)2(micro-H2O)](CH3OH) (4), {[Co(L1)2(L5)(CH3OH)2]}infinity (5), and {[Ni(L1)2(L5)(CH3OH)2]}infinity (6) (L2 = 2,2'-bipyridine, L3 = 1,4-diazabicyclo[2.2.2]octane, L4 = 1,10-phenanthroline, and L5 = 4,4'-bipyridine). 1 has a dinuclear structure that is further assembled to form a one-dimensional (1D) chain and then a two-dimensional (2D) network by the C-H...O H-bonding and pi...pi stacking interactions jointly. 2 takes a tetranuclear structure due to the existence of the chelating L2 ligand. 3 possesses a 1D chain structure by incorporating the related auxiliary ligand L3, which is further interlinked via interchain pi...pi stacking, resulting in a three-dimensional (3D) network. 4 also has a dinuclear structure and then forms a higher-dimensional supramolecular network through intermolecular pi...pi stacking and/or C-H...pi interactions. 5 and 6 are isostructural complexes, except they involve different metal ions, showing 1D chain structures, which are also assembled into 2D networks from the different crystallographic directions by interchain pi...pi stacking and C-H...pi interactions, respectively. The results reveal that the steric bulk of the anthracene ring in HL1 plays an important role in the formation of 1-6. The magnetic properties of the complexes were investigated, and the very long intermetallic distances result in weak magnetic coupling, with the exception of 1 and 3, which adopt the typical paddle-wheel structure of copper acetate and are thus strongly coupled.     

Transformations of griseofulvin in strong acidic conditions--crystal structures of 2'-demethylgriseofulvin and dimerized griseofulvin

The structure of griseofulvic acid, C16H15ClO6, at 100 K has orthorhombic (P2(1)2(1)2) symmetry. It is of interest with respect to biological activity. The structure displays intermolecular O-H...O, C-H...O hydrogen bonding as well as week C-H...pi and pi...pi interactions. In strong acidic conditions the griseofulvin undergoes dimerization. The structure of dimerized griseofulvin, C34H32C12O12 x C2H6O x H2O, at 100 K has monoclinic (P2(1)) symmetry. The molecule crystallized as a solvate with one ethanol and one water molecule. The dimeric molecules form intermolecular O-H...O hydrogen bonds to solvents molecules only but they interact via week C-H...O, C-H...pi, C-Cl...pi and pi...pi interactions with other dimerized molecules.     

Silver(I) complexes in coordination supramolecular system with bulky acridine-based ligands: syntheses, crystal structures, and theoretical investigations on C-H...Ag close interaction

In our efforts to investigate the coordination architectures of transition metals and organic ligands with tailored structures, we have prepared two structurally related rigid bulky acridine-based ligands, 9-[3-(2-pyridyl)pyrazol-1-yl]- acridine (L(1)) and 9-(1-imidazolyl)acridine (L2), and synthesized and characterized four of their Ag(I) complexes, {[AgL1](ClO4)}2 (1), {[AgL1](NO3)}2 (2), [AgL2(2)](ClO4) (3), and {[(Ag3L2(3))(NO3)](NO3)2(H2O)}(infinity) (4). The single-crystal X-ray diffraction analysis shows that the structures of 1 and 2 are similar to each other, with the two intramolecular Ag(I) centers of each complex being encircled by two L1 ligands; this forms a unique boxlike cyclic dimer, which is further linked to form one-dimensional (1D) chains of 1 and a two-dimensional (2D) network of 2 by intermolecular face-to-face pi...pi stacking and/or weak C-H...O hydrogen-bonding interactions, respectively. 3 has a mononuclear structure, which is further assembled into a 2D network via intermolecular Ag...O and pi...pi stacking weak interactions. 4 possesses two different 1D motifs that are further interlinked through interlayer face-to-face pi...pi stacking and Ag...O weak interactions, resulting in a 2D network. It is worth noting that one of the interesting structural features of 1, 2, and 4 is the presence of obvious C-H...M hydrogen-bonding interactions between the Ag centers and some acridine ring H atoms identified by X-ray diffraction on the basis of the van der Waals radii. Furthermore, as a representative example, full geometry optimization on the basis of the experimental structure, the natural bond orbital (NBO), and topological analysis of 1 were carried out by DFT and AIM (Atoms in Molecules) calculations. The total C-H...Ag interaction energy in 1 is estimated to be about 14 kJ/mol. Therefore, this work offers three new rare examples (1, 2, and 4) that exhibit C-H...Ag weak interactions, in which the N donors of the acridine rings coordinate to Ag(I) ions. Also, these results strongly support the existence of C-H...Ag close interactions and allow us to have a better understanding of the nature of such interactions in the coordination supramolecular systems.     

Encapsulation of divalent tetrahedral oxyanions of sulfur within the rigidified dimeric capsular assembly of a tripodal receptor: first crystallographic evidence of thiosulfate encapsulation within neutral receptor capsule

A simple tris(2-aminoethyl)amine based meta-chloro substituted tripodal thiourea receptor L has been extensively studied with two divalent oxyanions of sulfur, such as sulfate and thiosulfate, with identical dimensionality. The solid state crystal structure of the anion complexes with L reveal that the anions are encapsulated within the dimeric rigid capsular assembly of the receptor via N-Hanion interactions. To the best of our knowledge this is the first report on the encapsulation of thiosulfate within dimeric capsular assembly of a neutral receptor. The tight capsular sizes for both anion complexes are quite comparable, whereas the coordination mode of the anions and the hydrogen bonding parameters are significantly varied. The three dimensional solid state structural orientations of the capsular complexes are mainly governed by the ClCl (for thiosulfate complex) and ClS (for sulfate complex) halogen bonding interactions. The solution-state binding and encapsulation of oxyanions by N-Hanion hydrogen bonding has also been confirmed by quantitative (1)H NMR titration and 2D NOESY NMR experiments. Both the experiments confirm that in contradiction of 2?:?1 solid state binding, in solution the studied anions are bound within the pseudocavity of the receptor with 1?:?1 binding stoichiometry. Moreover, the change in chemical shifts of thiourea -NH protons and the binding constant values suggest the receptor-sulfate interaction is more energetically favorable compared to the receptor thiosulfate interaction.     

Competitive anion binding aptitude of benzimidazole and amide functionality of a non-symmetrical receptor in solid state and solution phase

A novel non-symmetric tripodal receptor (L) with benzimidazole and amide –NH functionalities has been synthesised and a comparative study for anion binding aptitude of those functionalities has been performed in solid state and solution phase. The protonated receptors in solid state tend to form a pseudo-cavity around the octahedral hexafluorosilicate anion whilst in second complex, binding of one sulphate and two bisulphates in unison by two protonated units arises. The benzimidazole –NHs are the strongest hydrogen bond donors in both the crystals controlling dominance over amide –NHs. The neutral receptor being selective towards fluoride anion induces a naked eye visible colorimetric change. The ¹H NMR studies with the neutral and protonated form of the receptor suggest the strong involvement of amide –NH in anion binding in solution phase.     

Strongly blue-shifted C-H stretches: interaction of formaldehyde with hydrogen fluoride clusters

The equilibrium structures, binding energies, and vibrational spectra of the cyclic, hydrogen-bonded complexes formed between formaldehyde, H(2)CO, and hydrogen fluoride clusters, (HF)(1< or =n < or =4), are investigated by means of large-scale second-order M?ller-Plesset calculations with extended basis sets. All studied complexes exhibit marked blue shifts of the C-H stretching frequencies, exceeding 100 cm(-1) for n = 2-4. It is shown that these blue shifts are, however, only to a minor part caused by blue-shifting hydrogen bonding via C-H...F contacts. The major part arises due to the structural relaxation of the H(2)CO molecule under the formation of a strong C=O...H-F hydrogen bond which strengthens as n increases. The close correlation between the different structural parameters in the studied series of complexes is demonstrated, and the consequences for the frequency shifts in the complexes are pointed out, corroborating thus the suggestion of the primary role of the C=O...H-F hydrogen bonding for the C-H stretching frequency shifts. This particular behavior, that the appearance of an increasingly stronger blue shift of the C-H stretching frequencies is mainly induced by the formation of a progressively stronger C=O...H-F hydrogen bond in the series of H(2)CO...(HF)(1< or =n < or =4), complexes and only to a lesser degree by the formation of the so-called blue-shifting C-H...F hydrogen bond, is rationalized with the aid of selected sections of the intramolecular H(2)CO potential energy surface and by performing a variety of structural optimizations of the H(2)CO molecule embedded in external, differently oriented dipole electric fields, and also by invoking a simple analytical force-field model.     

Tripodal nitro-imidazolium receptor for anion binding driven by (C-H)+- - -X- hydrogen bonds

[structure: see text] A positively charged tripodal receptor with nitro groups in the imidazolium rings was designed, synthesized, and characterized for its anion binding strength. The receptor shows strong affinity and high selectivity for Cl- through (C-H)+- - -X(-) hydrogen bonds wherein charge-charge and charge-dipole electrostatic interactions dominate. The association constant with chloride anion in a 9:1 mixture of acetonitrile-d3 and DMSO-d6 is measured to be 1.1 x 10(6) M(-1). The receptor also shows reasonably high affinity toward H2PO4-.     

Dramatic Enhancement of Binding Affinities Between Foldamer‐Based Receptors and Anions by Intra‐Receptor π‐Stacking

As a synthetic model for intra‐protein interactions that reinforce binding affinities between proteins and ligands, the energetic interplay of binding and folding was investigated using foldamer‐based receptors capable of adopting helical structures. The receptors were designed to have identical hydrogen‐bonding sites for anion binding but different aryl appendages that simply provide additional π‐stacking within the helical backbones without direct interactions with the bound anions. In particular, the presence of electron‐deficient aryl appendages led to dramatic enhancements in the association constant between the receptor and chloride or nitrate ions, by up to three orders of magnitude. Extended stacking within the receptor contributes to the stabilization of the entire folding structure of complexes, thereby enhancing binding affinities.     

Syntheses, structures, photoluminescence, and magnetic properties of phenanthrene-based carboxylic acid coordination polymers

Four new coordination complexes, M2(Htmopa)4(H2O)4 (M = Zn2+ (1), Mn2+ (2), (M(Htmopa)2(H2O)2)n (M = Ni2+ (3), Co2+ (4)), have been synthesized by the hydrothermal reaction of Htmopa (Htmopa = 2,3,6,7-tetramethoxyphenanthrene-9-carboxylic acid) with different transition metals at a suitable temperature. Single-crystal determinations revealed that 1 and 2 are isostructural and possess a dinuclear subunit, each connected into 3D networks by hydrogen bonds and C-H...pi interactions. 3 and 4 are also isostructural: the metal ions are bridged through water molecules and carboxylate oxygen atoms to form 1D wavelike double chains, and these double chains are further extended to a 3D network via hydrogen bonds and C-H...pi interactions. The photoluminescent properties of the free Htmopa ligand and its complexes have been studied in the solid state at room temperature. Both Htmopa and 1 exhibit strong blue emissions. Magnetic susceptibility measurements indicate that 2 and 3 exhibit antiferromagnetic coupling, whereas 4 shows a ferromagnetic coupling and exhibits a single-ion behavior of the Co II ion at a higher temperature range.     

Spectroscopic, structural, and theoretical studies of halide complexes with a urea-based tripodal receptor

A urea-based tripodal receptor L substituted with p-cyanophenyl groups has been studied for halide anions using (1)H NMR spectroscopy, density functional theory (DFT) calculations, and X-ray crystallography. The (1)H NMR titration studies suggest that the receptor forms a 1:1 complex with an anion, showing a binding trend in the order of fluoride > chloride > bromide > iodide. The interaction of a fluoride anion with the receptor was further confirmed by 2D NOESY and (19)F NMR spectroscopy in DMSO-d(6). DFT calculations indicate that the internal halide anion is held by six NH···X interactions with L, showing the highest binding energy for the fluoride complex. Structural characterization of the chloride, bromide, and silicon hexafluoride complexes of [LH(+)] reveals that the anion is externally located via hydrogen bonding interactions. For the bromide or chloride complex, two anions are bridged with two receptors to form a centrosymmetric dimer, while for the silicon hexafluoride complex, the anion is located within a cage formed by six ligands and two water molecules.     

Recognition, encapsulation, and selective fluorescence sensing of nitrate anion by neutral C3-symmetric tripodal podands bearing amide functionality

A series of neutral C(3)-symmetric acyclic artificial receptors incorporating amide functionality has been designed, synthesized, and fully characterized. Upon protonation, these conformationally flexible N-bridged tripodal podands 1-5 form in situ cone shape conformation through hydrogen bonding and C-H···π interactions. The protonation-induced interior preorganized cavity is capable of entrapping nitrate anions through the amide N-H bonds to form discrete nitrate complexes (1a-5a), which were fully characterized by NMR, HRESI mass spectra, and single crystal structures. By incorporating suitable fluorophores at each branch of the tripod receptor, the resulting fluorescent receptor 5 selectively recognized nitrate anions by fluorescent quenching in a DMSO solution and displayed one of the highest binding affinities for nitrate anions reported so far in polar media. Receptor 5 represents a unique example of a neutral receptor for the recognition of nitrate anions in polar solvent media by its zwitterionic form. The possible mechanism of proton-induced preorganization of these flexible, acyclic receptors in a convergent cone conformation followed by nitrate complexation has been proposed to rationalize the effective nitrate recognition.     

Investigating the effect of hydrogen bonding environments in amide cleavage reactions at zinc(II) complexes with intramolecular amide oxygen co-ordination

Amide oxygen co-ordination to a zinc(II) ion around a hydrogen bonding microenvironment is a common structural/functional feature of metalloproteases. We report two strategies to position hydrogen bonding groups in the proximity of a zinc(II)-bound amide oxygen, and we investigate their effect on the stability of the amide group. Polydentate tripodal ligands (6-R1-2-pyridylmethyl)-R2 (R1= NHCOtBu, R2= N(CH2-py-6-X)2 X = H L1, X = NH2, H L2, X = NH2 L3) form [(L)Zn]2+ cations (L =L1, 1; L2, 2; L3, 3) with intramolecular amide oxygen co-ordination (1-3), and intramolecular N-H...O=C(amide) hydrogen bonding (2, 3) rigidly fixed by the ligand framework. 1-3 undergo cleavage of the tert-butyl amide upon addition of Me4NOH.5H2O (1 equiv.) in methanol at 50(1) degrees C. Under these conditions the half-life, t(1/2), of the amide bond is 0.4 h for 1, 9 h for 2 and 320 h for 3. Mononuclear zinc(II) complexes of (6-NHCOtBu-2-pyridylmethyl)-R2(R2= N(CH2CH2)2S) L4 and chelating N2 ligands without hydrogen bonding groups (1,10-phenanthroline L5, 2-(aminomethyl)pyridine L6) as control compounds, and with an amino hydrogen bonding group (6-amino-2-(aminomethyl)pyridine L7) have been synthesised. Amide cleavage is in this case faster at the zinc(II) complex with the amino hydrogen bonding group. Thus, hydrogen bonding environments can both accelerate and slow down amide bond cleavage reactions at zinc(II) sites. Importantly, the magnitude of the effect exerted by the hydrogen bonding environments was found to be significant; 800-fold rate difference. This result highlights the importance of hydrogen bonding environments around metal centres in amide cleavage reactions, which may be relevant to the chemistry of natural metalloproteases and applicable to the design of more efficient artificial protein cleaving agents.     

硫脲类阴离子受体的研究进展

阴离子识别是超分子化学研究的重要内容之一,其关键环节是构筑可识别阴离子的结合受体,后者以非共价键力如静电作用、疏水作用、氢键等与阴离子结合.本文详细评述了近5年来硫脲类阴离子识别受体的设计、结构及其阴离子识别作用的研究进展.     

Amide-ligand hydrogen bonding in reverse micelles

One approach to modeling the second coordination shell of metalloproteins is to pair amide-containing counterions with metal complexes to form hydrogen bonds in the solid state. In a more general approach, we have designed a surfactant counterion that can sustain hydrogen bonding interactions with metal complexes in solution. The surfactant is cationic and incorporates an amide as part of its headgroup to form hydrogen. The surfactant forms hydrogen bonding reverse micelles that accommodate anionic metal complexes in their polar core. In reverse micelles containing an iron(III) hexacyanide complex, spectroscopic evidence suggests that the anion is confined to the polar core region in solution. Single-crystal X-ray diffraction data on the surfactant ferricyanide system reveals a layered structure with interdigitated alkyl chains and an extensive network of hydrogen bonds that link amide groups to the cyanide ligands and to neighboring headgroups.     

A molecular shuttle for driving a multilevel fluorescence switch

A [2]rotaxane-based molecular shuttle comprised a macrocycle mechanically interlocked to a chemical "dumbbell" has been prepared in high yields by a thermodynamically controlled, template-induced clipping procedure. This molecular shuttle has two different recognition sites, namely, -NH2 +- and amide, separated by a phenyl unit. The macrocycle exhibits high selectivity for the -NH2+- recognition sites in the protonated form through noncovalent interactions, which include 1) N+-H...O hydrogen bonds; 2) C-H...O interactions between the CH2NH2+CH2 protons on the thread and the oligo(ethylene glycol) unit in the macrocycle; 3) pi...pi stacking interaction between macrocycle and aromatic unit. Upon deprotonation of the [2]rotaxane the macrocycle glides to the amide recognition site due to the hydrogen bonds between the -CONH- group and the oligo(ethylene glycol) unit in the macrocycle. The deprotonation process requires about 10 equivalents of base (iPr2NEt) in polar acetone, while the amount of base is only 1.2 equivalents in apolar tetrachloroethane. Upon addition of Li+, the conformation of the [2]rotaxane was altered as a result of the collective interactions of 1) hydrogen bonds between pyridine nitrogen and amide hydrogen atoms; 2) coordination between the oligo(ethylene glycol) unit, amide oxygen atom and Li+ cation. Then, when Zn2+ ions are added, the macrocycle returns to the deprotonated -NH- recognition site owing to coordination of the macrocycle and -NH- from the axle with the Zn2+ ion. All the above-mentioned movement processes are reversible through the alternate addition of TFA/iPr2NEt, Li/[12]-crown-4 and Zn2+/ethylenediaminetetraacetate (EDTA), by virtue of hydrogen bonding and metal-ion complexation. Significantly, the three independent movement processes are all accompanied by fluorescent responses: 1) complete repression in the protonated form; 2) low-level expression in the deprotonated form; 3) medium-level expression following addition of Li+; 4) high-level expression on complexation with Zn2+.     

Heterodimetallic germanium(IV) complex structures with transition metals

The hydrothermal synthesis and structural characterization of a number of complex compounds containing the divalent tris(oxalato-O,O')germanate anion, [Ge(C2O4)3]2-, or the neutral bis(oxalate-O,O')germanium fragment, [Ge(C2O4)2], with transition-metal (M) cationic complexes of 1,10'-phenanthroline (phen) is reported: [M(phen)3][Ge(C2O4)3].xH2O [where M2+ = Cu2+ (1a and 1b), Fe2+ (2a and 2b), Ni2+ (3), Co2+ (4); x = 0.2 for 2b], [MGe(phen)2(mu2-OH)2(C2O4)2] [where M2+ = Cd2+ (5) and Cu2+ (6)]. The isolation of two polymorphs with Cu2+ (1a and 1b) and other pseudo-polymorphs for Fe2+ (2a and 2b) was rationalized based on slightly different molar ratios for the starting materials. All compounds have been characterized using EDS, SEM, vibrational spectroscopy (FT-IR and FT-Raman), thermogravimetry, and CHN elemental composition and their structure determined on the basis of single-crystal X-ray diffraction studies. The crystal packing of the different chemical moieties for each series of compounds was discussed on the basis of the various intermolecular interactions present (strong C-H...pi and weak C-H...O hydrogen-bonding interactions, C-H...pi and pi-pi contacts).     

A quinoline based bis-urea receptor for anions: a selective receptor for hydrogen sulfate

A dipodal bis-urea receptor has been synthesized from the reaction of 8-amino quinoline and 1,4-phenylene diisocyanate in dichloromethane, and the anion binding ability of the receptor has been studied using fluoride, chloride, bromide, iodide, perchlorate, nitrate, dihydrogen phosphate and hydrogen sulfate by UV-Vis titrations in DMSO. The results show that the receptor binds each of the anions with a 1:1 stoichiometry, showing high affinity and moderate selectivity for hydrogen sulfate among the anions studied. Ab initio calculations based on density functional theory (DFT) suggest that an anion (X(-)) is bonded within the cleft formed by the two arms of the receptor through two NH...X(-) and two aromatic CH...X(-) interactions. The results from solution and theoretical studies suggest that binding is predominantly influenced by hydrogen bonding interactions and the basicity of anions.     

Participation of benzene hydrogen bonding upon anion binding

A m-xylene-bridged imidazolium receptor, 1, has been designed and synthesized. The receptor 1 utilizes two imidazole (C-H)(+)- - -anion hydrogen bonds and one benzene hydrogen- - -anion hydrogen bond. The major driving force of complexation between the receptor 1 and anions comes from two imidazole (C-H)(+)- - -anion hydrogen bonds. However, both NMR experiments and ab initio calculations show that the benzene hydrogen attracts the anion guests, clearly indicating benzene (C-H)- - -anion hydrogen bonding. [reaction: see text]     

Self-assembly of 1:2 inclusion complexes between a metallocycle host and dihydroxyaromatic guests: a redox controlled complexation process

Two new 1:2 inclusion complexes were prepared by self-assembly of three components: a ligand based on 4,4'-bipyridinium, a square-planar Pd complex, and a dihydroxyaromatic guest (hydroquinone or 1,5-dihydroxynaphthalene) in a 2:2:2 ratio. Their X-ray structural analyses revealed that the complexes are stabilized by pi-pi stacking and [C-H...pi] interactions.     

Early-late, mixed-metal compounds supported by amidophosphine ligands

The sequential syntheses, structural characterisation and reactivity studies of a series of discrete early-late mixed-metal complexes supported by the unique amidophosphine ligand m-(But2CH)N(C6H4)PPh2L1 are described. This ligand was synthesised using a Schiff-base/ButLi protocol and the resultant lithium salt LiL1 found to adopt a tetrameric structure in the solid state in which both two-coordinate N-Li-N and eta6:eta6-arylLi metallocene bonding motifs are present. Reaction between HL1 and labile Pt(II) and Pd(II) chlorides formed MCl2(HL1)2 complexes 4 (M = Pt) and 5 (M = Pd) in which a weak N-H...pi(aryl) hydrogen bonding interaction was identified in the solid-state structure of 4. These compounds were found to be inert to transamination and protonolysis reactions with Ti amides and alkyls; instead, stepwise alkyl transfer from Ti to Pt, resulting in Pt(CH2SiMe3)2(HL1)2 6 was observed. Access to mixed-metal complexes was achieved using an early-metal-first approach. Reaction between the metalloligand TiCl2(L1)2 and labile Group 10 and group 9 compounds resulted in the formation of TiCl2(mu-L1)2PtCl2 8, TiCl2(mu-L1)2PtMe2 9, TiCl2(mu-L1)2PdCl2 10, TiCl2(mu-L1)2NiBr2 11, and [TiCl2(mu-L1)2RhCl(CO)]2 12. In the solid state, the Group 4/10 compounds 8, 9 and 10 adopt similar structures that exhibit both intramolecular But2C-H...Cl-Ti hydrogen bonding and arylNP pi-stacking interactions; this hydrogen-bonding interaction is conserved in solution. Unlike the above Group 4/10 complexes, the Ti-Rh complex 12 adopts a tetranuclear structure in the solid state that is stabilised by similar hydrogen-bonding and pi-stacking interactions. The Group 4/10 complexes were assessed as catalysts for olefin polymerisation and cross-coupling reactions. In combination with MAO, the mixed-metal complexes 8 and 10 were poor ethylene polymerisation catalysts and resulted in polymers of both high molecular weight and polydispersity. The Ti-Ni complex 11 formed oligomeric material only, while the mononuclear Ti metalloligand TiCl2(L1)2 gave the best results, showing low activity (6.14 kg mol(-1) bar(-1) h(-1)) and moderate polydispersity (12). The Ti-Pd complex 10 was assessed in arylamination and Suzuki-Miyaura reactions. While little or no catalytic activity was observed in arylamination reactions, 10 was found to effect Suzuki coupling between activated aryl bromides and phenylboronic acid at 80 degrees C. Unlike with TiCl2(L1)2, reactions between 8 and the reducing agents C8K or Mg led to intractable mixtures. However, the cyclic voltammetry of both compounds indicated that a reversible one-electron reduction process occurs at a similar potential (ca. -0.7 V) and was assigned to the formation of the monohalides TiCl(L1)2 and TiCl(mu-L1)2PtCl2. The reactivity of the metallocage TiCl(mu-L3)3Pt was also investigated. While reduction reactions were unsuccessful, the metallocage reacted with CO to form the Ti-Pt carbonyl, TiCl(mu-L3)3Pt(CO) 13. The X-ray crystal structure of 13 revealed that accommodation of CO at the Pt centre has caused the cage expansion and loss of agostic aryl-H...Pt interactions. Furthermore, reaction of TiCl(mu-L3)3Pt with excess MeI resulted in the formation of the Ti(IV)-Pt(II) complex trans-TiCl2(mu-L3)2(kappa1-L3MeI)Pt(Me)I.