An amperometric method has been developed for continuous determination of iodine concentrations of the order of 10-5 molar. Catalysis of the bromate-iodide and iodate-iodide reactions by carboxylate and phoshphate ions has been shown to occur. The rates of these reactions may be expressed: -d(BrO⁻₃)/dt = k₀(H⁺)²(I⁻)¹(Br0⁻₃)¹ + kb(B⁻)¹(H⁺)²(I⁻)¹(BrO₃)¹ -d(IO⁻₃)/dt = k₀(H⁺)²(I⁻)²(IO⁻₃)¹ + kb(B⁻)¹(H⁺)²(I⁻)²(IO⁻₃)¹/1 + k'(I⁻)¹ The structure of the iodate ion in solution has been investigated. It has been concluded that the predominant species is the pyramidal IO-3 ion, and any aquated form is present to the extent of no more than one part in 108. Previous studies of halate-halide and related reactions have been reviewed, and mechanisms have been postulated for these reactions on the basis of available information.

This thesis deals with thiocarbonyl complexes of ruthenium and osmium [LnM-CS]. In chapter 1 a comprehensive review of all transition metal thiocarbonyl complexes is presented. Unlike carbon monoxide, carbon monosulphide is a highly reactive molecule which does not exist under normal laboratory conditions. However, transition metal complexes of this reactive intermediate are typically stable compounds of which there are now approximately two hundred reported examples. This small number has made a complete review possible. Slow spasmodic growth has accompanied transition metal thiocarbonyl chemistry since the prototype complex was discovered in 1966 and chapter 1 discusses the synthetic reasons for this, describes critically the current bonding models, and presents the reactions of thiocarbonyl complexes. The very new field of the chemistry of selenocarbonyl complexes [LnM-CSe] is included and comparison with this and with the well-documented chemistry of carbonyl complexes allows for an analysis of periodic changes. The review indicates that CS ligand reactions had received little attention at the outset of this project. Interligand reactions involving CS were unknown primarily because thiocarbonyl complexes containing ligands suitable for investigating reactions of this type had not been synthesised. In particular, transfer of hydrido or aryl ligand to CS had not been observed. Such reactions are the subjects of chapters 3 and 6. The investigation of these transfer reactions necessitated the prior preparation of complexes containing hydrido or aryl ligands cis to the thiocarbonyl ligand. Suitable complexes were synthesised from the very versatile synthetic intermediate OsCl2 (CS) (PPh3)3 [Chapter 3], which was discovered after considerable effort had been devoted to finding high yield routes for introducing the CS ligand into the coordination sphere of ruthenium and osmium [Chapter 2]. Chapter 3 is concerned with hydride transfer to the CS ligand. The thioformyl ligand [OS-C-H-S] results from the transfer of one hydrido ligand to CS and subsequent reactions, which are also probably hydride transfers, produce the thioformaldehyde [Os-S-C-H-H] and methylthiolato [Os-SCH3] ligands. The possible relevance of these ligands as models for postulated intermediates in the Fischer-Tropsch synthesis is noted. The thioformyl and thioformaldehyde ligands were hitherto unknown and the formulations have been additionally verified by investigating the reactivity of these novel ligands and characterising the derivatives obtained. A synthetic route to secondary carbine complexes and to nitrogen and oxygen equivalents of the thioformyl ligand [Os-C-H—NMe and Os-C-H—O] is demonstrated. The review in chapter 1 also recounts how observation has shown that strong σ-donor and strong π-acceptor properties of the CS ligand exert a profound effect upon the reactivity of CS complexes. In particular, strong π-acceptor properties mark the CS ligand as an ideal candidate for stabilising very electron-rich metal centres such as d8 ruthenium(O) or osmium(O). In chapter 4 high yield routes to zerovalent osmium thiocarbonyl complexes are detailed and the reactivity of these complexes is exploited to afford the first high yield syntheses of dithiocarbonyl complexes. The thiocarbonyl ligand is also viewed, from the collected information in chapter 1, as being more responsive to the coordinative environment than the better-known carbonyl ligand. Thus, while CS can remove more electron-density from basic metal centres than CO, CS can also donate more electron-density than CO when coordinated to very electron-poor metal centres. Consequently, it is not surprising that reactions which have been regarded in a classical sense as electrophilic or nucleophilic attack at CO are also found for CS. In chapter 5 several novel reactions which can be described as nucleophilic attack at the CS carbon atom are reported for both neutral and cationic complexes. One such reaction is an interligand reaction of cis thiocarboxamido and thiocarbonyl ligands which affords a four-membered osmium metallocycle. Chapter 6 describes how coordinatively unsaturated aryl-thiocarbonyl-containing complexes react with potentially bidentate anionic ligands to produce coordinatively saturated complexes. coordinative saturation also occurs with carbon monoxide or isocyanide and these latter compounds undergo a rearrangement reaction which involves the thiocarbonyl ligand. Available evidence, which includes the results of an incomplete X-ray crystal structure determination, suggests that a bidentate thioacyl ligand [Os-S-C-R] is produced by transfer of the aryl ligand to CS with ring-closure. Some further reactions of this novel ligand are also discussed. In conclusion, the work reported here extends this research group’s interest in the chemistry of low valent transition metal compounds and the ligands which stabilise such compounds to thiocarbonyl complexes of ruthenium and osmium. The present status of the chemistry of transition metal thiocarbonyl complexes has been examined and the work presented in the experimental chapters contributes to this small area of chemistry by examining, for the first time, interligand reactions which involve CS, by providing synthetic routes to CS complexes of osmium(O), and by beginning to examine the synthetic potential of the novel compounds and ligands obtained.

Copolymerisation of ethyl cellulose (EC) with methyl methacrylate (MMA) and vinyl acetate was carried out in solution, using a number of free radical initiators, to form graft copolymers with grafting yields up to 63% and weight average molecular weight about 9 x 104 g mol-1 Graft copolymerisation of MMA and EC appears to involve participation of comonomer charge transfer complexes at the initial stage of reaction, Interaction of EC with the carbonyl group of MMA enhances the electron-accepting ability of EC and promotes the formation of a donor-acceptor complex as matrix, with the resultant generation of a covalent bonded monomer radical, which then propagates in the usual manner to produce EC-g-PMMA. The influence of a number of experimental variables on the grafting efficiency of the EC-g-PMMA reaction, and the properties of the resulting copolymers, was investigated. The initiator has a significant effect on the grafting efficiency, which decreases in the order azobisisobutyronitril>ammonium persulphate>potassium persulphate>Ce(IV) ion. Benzoyl peroxide was found to be unsuitable because it promoted degradation of ethyl cellulose chains. The order of solvent influence on the grafting yield is chloroform>toluene>benzene. The grafting yield is also reaction time and temperature dependent. A2-3 hour reaction time and 40-50°C reaction temperature gives a substantial increase in both reaction rate and the molecular weight of the graft copolymer product. The introduction of PMMA graft side chains onto EC main chains leads to a significant decrease in the radius of gyration in solution, as determined by size exclusion chromatography, compared to linear EC. This finding is explained by the theory of Stockmayer and Fixman in terms of the number and type of long chain graft points in the molecule, Calculation of viscosity of EC-g-PMMA in solution using the Kurata equation gave values in good agreement with the experimentally determined viscosity. A significant result is that grafting PMMA branches onto EC reduces the hydrodynamic volume, and differential scanning calorimetry showed conclusively that increasing PMMA sidechain length reduces the chain flexibility, by reduction of free volume. The glass transition temperature of EC-g-PMMA, produced by using a large excess of MMA monomer and reasonably long reaction time, was shifted to higher temperature with increase of grafting yield and molecular weight. A single glass transition is observed for copolymers made using low initiator concentrations, and two glass transitions are found for higher initiator concentrations. In addition, EC-g-PMMA samples with higher grafting yield are more brittle than those with lower grafting yield. However, both the bending modulus (determined by dynamic mechanical thermal analysis) and elongation at break increase with grafting yield. Our experiments proved that the crystallinity of EC-g-PMMA is less than that of pure EC and greater than that of pure amorphous PMMA. The specific oxygen gas-permeability coefficients of EC-g-PMMA films decrease with increase of grafting yield. The reason is that grafting decreases of hydrodynamic volume. Interestingly, X-ray diffraction showed that the higher the grafting yields of EC-g-PMMA, the higher its crystallinity. Films of EC-blend-PMMA, made by solution casting and examined in cross section using scanning electron microscopy, showed an essentially multiple layer morphology with non-uniform dispersion of PMMA in the EC matrix. Scanning electron microscopy confirmed, as expected, that EC-g-PMMA cast films were homogeneous with no evidence of phase separation. The tensile strength of EC-g-PMMA films was typically about 20% higher than that of EC-blend-PMMA films, and the graft copolymer films exhibited greater oxygen permeability. A new model for graft copolymerisation to EC is proposed. The model provides for the possibility that grafting to EC with 48% ethoxy content can occur at the five OC2H5 groups and one OH group per unit. It was established using NMR spectrometry of EC-g-PMMA and EC-g-Poly (vinyl acetate) that under some conditions the ethoxy groups are the favoured graft sites. The liquid crystalline properties of EC and EC-g-PMMA were extensively investigated. Optical microscopy with crossed polarisers revealed that the relatively short mesomorphic temperature range of ethyl cellulose is extended downwards almost to ambient temperature in the graft copolymer. Low frequency Raman scattering showed that EC-g-PMMA has higher light scattering intensity than EC at ambient temperature. But it was lower than that of EC at 191°C. Moreover, the Jaynes-Cummings model cannot predict the light scattering intensity of EC-g-PMMA as a function of frequency very well, whereas the EIT-Kerr scheme is able to successfully account for the experimental observations. It was found that EC and EC-g-PMMA are pseudoplastic, lyotropic and thermotropic materials whose viscosity in solution is dependent on many factors, particularly on temperature and solution concentration. Both materials show unusual rheological behaviour, including maxima in the isothermal concentration dependence of viscosity. Unmodified EC exhibits thixotropic flow behaviour, whereas grafting PMMA side chains onto EC changes the flow behaviour to rheopectic, which is also typical of PMMA itself. As the temperature and concentration increase, the viscosity increases in response to the transition from an isotropic to an anisotropic state of EC-g-PMMA. Furthermore, experiments on the distinguishing characteristics of EC-g-PMMA indicate that different solvents affect its anisotropic flow behaviour to a greater or lesser extent. In particular, chloroform shows a stronger flow orientation effect than tetrachloroethane on EC-g-PMMA solutions. The rheological behaviour of EC and EC-g-PMMA in the nematic phase is much more complex than that of ordinary polymers or low molecular weight liquid crystals. The Doi theory is usually applicable to ordinary polymers or low molecular weight liquid crystals, but cannot predict shear stress as a function of shear rate; particularly at very low shear rates for EC and EC-g-PMMA. Whereas, the polydomain model is better to account for the observations. Measurements of thermally stimulated depolarisation current showed that EC-g-PMMA has a longer dipolar relaxation time in an electrical field. Molecular dipole motions of EC give a maximum depolarisation current at 138 °C in the glass transition region and another maximum near 200 °C, corresponding to dipolar relaxation in the liquid crystalline phase. EC-g-PMMA shows a broader dipolar relaxation temperature range in the liquid crystalline phase and the depolarisation current maximum shifts to a lower temperature. We have observed that field induced polarisation of EC-g-PMMA is affected by the length of the PMMA side chain, and obeys an interfacial model of the Maxwell-Wagner-Sillars type. It was confirmed by X-ray photoelectron spectroscopy that the length of the PMMA side chain could affect the surface properties. EC-g-PMMA has higher photoemission intensity than EC, and the photoemission intensity and depolarisation current increase with grafting yield.

This thesis is concerned with the utilisation of the natural product, abieta-8,11,13-trien-18-oic acid* (dehydroabietic acid) (1) for the synthesis of optically active steroids and diterpenoids. The work has been divided into three sections which describe transformations of rings A, B and C of abieta-8,11,13-trien-18-oic acid (1). Selective epoxidation of the alkene mixture (3-5) derived from oxidative decarboxylation of abieta-8,11,13-trien-18-oic acid (1) with lead tetraacetate has given the epoxides (64), (65), a low yield of the epoxide (66), and the pure exocyclic alkene (3). The alkene (3) was oxidised to the ketone (6) which has been previously employed as an intermediate for the synthesis of the α,β-unsaturated ketone (10). The epoxides (64) and (65) have been converted to the unsaturated ketones (89), (107), and (67), and the saturated ketones (13), (99) and (100). A study of the boron triflouride rearrangements of the three epoxides (64), (65) and (66) has been made using benzene and dimethyl suplhoxide as solvents, and pathways for the formation of the products are suggested. Peracid oxidation of the enol acetate (155) derived from the C 7-ketone (18) provided a facile introduction of oxygen substituents into the hindered C 6 position of abieta-8,11,13-trien-18-oic acid (1). By hydrogenolysis of the C 7-hydroxy substituent of the compound (162), the C 6-acetate (172) was obtained. Hydrolysis of the latter compound, and methylation of the acid formed gave the C 6-alcohol (175) which was oxidised to the C 6-ketone (176). The literature pertaining to the intramolecular functionalisation of aromatic alkyl groups has been surveyed, and, with the ultimate aim of synthesizing the aromatic steroids (237) and (249), the C 13-isopropyl group of abieta-8,11-13-trien-18-oic acid (1) has been functionalised by the application of two of the published procedure, viz. the lead tetraacetate oxidation of aromatic acids, and the thermolysis of diaxomethyl ketones. Nitration of methyl 12-acetylabieta-8,11,13-trien-18-oate (227) has given products of nitrodeacylation (44) and nitrodealkylation (266). The product of nitrodealkylation (266) has been converted to methyl 13-hydroxy-podocarpa-8,11,13-trien-18-oate (59) in 36% yield. Methylation of the phenol (59), and Birch reduction of the methyl ether (276) has given podocarp-8(14)-en-18-ol-13-one (281). Annelation of the α,β-unsaturated ketone (281) with bromoacetone was attempted in order to synthesize the steroid (284), but the only product identified was the furan (286). * The numbering system used throughout this thesis is that proposed by J.W. Rose (personal communication to Professor R. C. Cambie) in “The Common and Systematic Nomenclature of Cyclic Diterpenes” 3rd revision, Oct 1968, to be submitted to the IUPAC Commission on Organic Nomenclature.

High current anodization of magnesium and magnesium alloys Ellen Angharad Carter Pure magnesium and three magnesium alloys containing different amounts of aluminium (2-9%) plus zinc and manganese were anodized with constant current density in sodium hydroxide solution with and without fluoride or phosphate ions. Electric field strengths of resultant anodic films were calculated from galvanostatic transients. These transients showed three characteristic features: linear voltage increase, noisy high voltage signals accompanied by sparking, and sawtooth-like events characterized by instantaneous voltage drops followed by slower voltage increases. Each feature was linked to certain physical processes occurring in the metal/film/solution system. Oxidation of magnesium and magnesium alloys formed anodic films with bilayer structures: a passive barrier layer adhering to the metal electrode, topped by a porous secondary layer. Cation injection into the barrier film across the metal/oxide interface was the rate determining step for film growth. Interstitial cations migrated through the film under the influence of the electric field. At the film/solution interface they reacted with electrolyte species and either thickened the film or dissolved in solution. Electric field strength was constant for particular metal/solution combinations and was independent of applied current density. Changing the electrode material altered the resultant electric field strength: pure magnesium produced oxides with lower electric field strengths than films formed on the three magnesium alloys. Changing the electrolyte had no discernable effect on the electric field strength. Charge efficiency of the film growth process was investigated by oxygen gas evolution; efficiency decreased during sparking. Ion beam analysis (Rutherford backscattering, fluorine depth profiling and nuclear reaction analysis) coupled with X-ray photoelectron spectroscopy, scanning electron microscopy, X-ray diffraction studies and Raman spectroscopy gave information about the anodic film surface. These techniques showed that oxides formed on magnesium-aluminium alloys were thinner than those formed on pure magnesium caused by aluminium dissolution. Fluorine depth profiling revealed that concentration profiles for fluorine in anodic oxides formed in fluoride-containing solution altered depending on the aluminium content of the electrode material.

The mechanisms proposed for the Clemmensen reduction of simple ketones are critically examined, and the Clemmensen reduction of difunctional ketones is reviewed. The Clemmensen reduction of a number of 1,4-diketones has shown that the products formed depend on the conformation of the carbonyl groups: (a) syn or anti-periplanar alignment of the carbonyl groups within the C2-C3 bond favours fragmentation e.g. cyclohexane-1,4-dione leads to hexane-2,5-dione and hex-5-oF-2-one, (b) with 1,2-diacetyl systems formation 3f alcohols and furans predominates e.g. hexane-2,5-dione gives hexan-2-ol, and 2,5-dimethyltetrahydrofuran, (c) when both carbonyl groups are in a large ring (≥C7) formation of cyclobutanediols is possible e.g. 2,6,6-trimethylcycloheptane-1,4-dione is reduced to 3,3,6-trimethylbucyclo[3,2,0]-1β-diol, (d) when none of these conditions is satisfied normal reduction occurs e.g. cholestane-3,6-dione yields cholestan-6-one. A mechanism is proposed for the formation of hexan-2-ol, hex-4-on-2ol, and 2,5-dimethyltetrahydrofuran from the Clemmensen reduction of hexane-2, 5-dione. The production of a number of similarly constructed 1,4-diketones and Y-functionalised ketones is also examined. The synthetic visibility of the fragmentation reaction, previously observed to occur under Clemmensen conditions, is investigated and it is shown that this is of limited value for the preparation of large rings. The stereochemical requirements for the reaction are verified and the mechanism is further studied. A review of the synthesis of 1,4-diketones is given and the preparation of the compounds used in this study is discussed in detail. The Clemmensen reduction of two 1,5-diketones is examined. The formation of cyclopropanediols and cyclopropanols from the Clemmensen reduction of some monocyclic formyl-ketones and β-hydroxy-ketones is discussed. The Clemmensen reduction of hexane-2,5-dione and pentane-2,4-dione with different metals is investigated.

This thesis is presented in three parts. The first is concerned with the solution and attempted refinement of the structure of prostratin, a toxic anti-tumour chemical extracted from the New Zealand tree pimelia prostrata. The second is concerned with the analysis of the structures of three inorganic compounds of current interest. These are; 1. bisethylenediaminenickel(II) hemioxalate nitrate 2. dipropylenetriaminezinc(II) hemioxalate perchlorate 3. diethylenetriaminecopper(II) hemioxalate perchlorate. The last section deals with the theory and programming of five of the more important computer programs developed during the course of the work.

A range of compounds related to the diquaternised salts of 2,2'-dtpyridine and 4,4'-dipyridine was studied in the present investigation. The effect of the change in the redox-state of the compounds was determined by vibrational spectroscopic and molecular orbital techniques. The investigation of 2,7-dimethylthieno[2,3-c:5,4-c'] dipyridinium diiodide monohydrate was undertaken by X-ray diffraction, vibrational spectroscopic and molecular-orbital techniques. These investigations showed that the thiophenic portion of the dication exhibited partial aromaticity. On formation of the radical monocation, a pattern of bond length changes consistent with the formation of a quinoidal structure was predicted by molecular-orbital calculations. This suggests that the electron delocalisation occurs over the entire molecule. The resonance Raman spectrum of the cation monoradical exhibits bands which may be assigned to the thiophenic portion, which suggests that this portion is associated with the chromophore. IR spectroscopic investigations into the electrogenerated radical of N,N'-diheptyl 4,4' - pyridinium, which has been investigated as the coloured component of electrochromic displays, were performed. The reflectance IR spectra of the radical monocations were obtained through bulk-sampling potential subtraction (PS) and surface-selective polarisation modulation (PM) techniques. The comparison between PS and PM spectra of the radical generated as a solid film in an aqueous medium, with the PS spectrum of the radical generated in acetonitrile revealed differences. These were interpreted in terms of an equilibrium between monomeric and aggregated forms of the radical. Similar results were obtained for the related compounds, methyl viologen and its dicyano substituted salt. The simplicity in the pattern of bands in the PS IR spectra of the monomeric radicals of methyl- and dicyanomethyl viologens was investigated by calculating the IR spectra of the dications and cation radicals of these compounds by molecular orbital techniques. The intense spectral features could be interpreted in terms of a charge-oscillation of the radical electron across the pyridine rings. The dipole moment of such modes is large and leads to the enhancement of these modes. The effect of various counterions associated with heptyl viologen was investigated by Raman and IR techniques. The pattern of bands in the Raman spectrum exhibited little variation with differing the counterions. The PS IR spectra exhibited disappearance features associated with the counterion in contrast to the PM spectra where no such bands were observed. PS IR spectra were also obtained by synchronising data acquisition with potential sweeps. The intensity of disappearance features in the PS IR spectra attributable to the CH modes varied at a similar rats to bands assigned to the radical aggregate. This suggested that a reorientation of the dipyridine ring and the quaternising alkyl chain probably occurs on reduction to form the radical. The lack of reversibility associated with the degradation of viologen films was investigated by PS IR techniques. The effect is probably associated with changes in the composition of the solid rather than a change in the concentrations of the monomeric and aggregated forms of the viologen radical. Dialkyl bridged diquaternary compounds of 2,2'-dipyridine were investigated by IR and theoretical techniques. The observation that the calculated dihedral angles for the dications and cation radicals were similar allowed the trends in the electronic absorption maxima (ultra-violet) and electrode potentials to be interpreted. Selective enhancements of bands in the PS IR spectra of the radicals suggest that a charge-oscillation mechanism may also be operative in these compounds. The utility of a combination of structural, theoretical and vibrational spectroscopic studies is demonstrated in these studies.

Introduction: General. The family Solanaceae, to which the Solanurn genus belongs, is comprised of some 70 genera and approximately 2000 species. Its members, which are herbs, erect or climbing shrubs and, occasionally, small trees, are distributed in the tropical and extend to the temperate regions, the greatest concentration being in Central and Southern America. The family's chief point of interest chemically is the fact that many of its members contain alkaloids, well known examples being Atropa belladonna (containing atropine), Datura strammonium(daturine), Nicotiana tobacum (nicotine), and Solmum tuberosum (solanine). The Solanum (Latin - solamen, solace or quieting) genus is made up of some 1,200 species, three of which, S. tuberosum (potato), S. lycopersicum = Lycopersicum esculentum Mill. ( tomato), and S . nigrum (a common weed of cultivation), are especially well known. New Zealand has one endemic species, namely S. aviculare Forst. Agriculturally, mainly because of S. tuberosum and S. lycopersicum, the genus is of course an important one but in addition several species are used in horticulture, e.g. S. pseudocapsicum and S. macrmthum, and a few species, e.g. S. mammosum and S. dulcamara, are reported as being of medicinal value. Chemically it is unique, in that may species contain glycosidic steroidal alkaloids and most attention has been devoted to the characterisation of these substances, although various other constituents, e.g. commarins and anthocyanins, have been reported.

This study concerns the synthesis, structure and reactivity of complexes of d⁶ and d⁸ osmium. The reactivity of certain ligands coordinated to low-valent osmium has also been investigated. Various hydride complexes of osmium(II) were prepared as potential precursors of osmium(O). OsH₄(PPh₃)₃ reacts with p-tolylisocyanide (TIC) and 4-ethyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane (ETPO) to yield OsH₂(L)(PPh₃)₃ from which were derived OsH₂(L’)(L)(PPh₃)₂ (L, L’=CO, TIC, ETPO). Attempts to eliminate hydrogen from the dihydrides failed. OsHCl(CO) (PPh₃)₃ reacts with neutral ligands L (=TIC, ETPO, P(OMe)₃, P(OPh)₃, PPh₂Me) to give OsHCl(CO)(L)(PPh₃)₂ which, with silver perchlorate (L=TIC, ETPO only) afford OsH(OClO₃)(CO)(L)(PPh₃)₂. The labile perchlorate ligand can be replaced by ligands L’ affording [OsH(CO)(L)(L’)(PPh₃)₂]ClO4 (L=TIC, L’=CO, TIC, PPh₃ L=ETPO, L’=CO, ETPO). OsHCl(CO)(PPh₃)₃ reacts with silver perchlorate in acetonitrile to yield [OsH(CO)(CH N)₂(PPh₃)₂]ClO4, which in turn reacts with neutral ligands to give [OsH(CO)(CH₃N)(L)(PPh₃)₂]ClO₄ (L=CO, TIC, ETPO, PPh₃). Cationic [OsH(CO)₂(PPh₃)₃]+ and [OsH(TIC)₂(PPh₃)₃]+ can be prepared from the action of PPh₃ on [OsH(CO)₂(CH₃N)(PPh₃)₂]+ and TIC on OsH(O₂CCH₃)(PPh₃)₃ respectively. With base, [OsH(CO)(CH₃N)(PPh₃)₃]ClO4 affords OsH(OH)(CO)(PPh₃)₃ from which a series of hydroxide complexes OsH(OH)(CO)(L)(PPh₃)₂ (L=CO, TIC ETPO) can be obtained. The hydroxide group in OsH(OH)(CO)(PPh₃)₃ is cleaved by acids HX to yield OsHX(CO)(PPh₃)₃ (X=F, Br, Cl, I, CH₂, CF₂, SC₇H₇, OClO₃). Those members of the series with X=CN, N₃, OCN, SCN were obtained from OsH(OClO₃)(CO)(PPh₃)₃ and the appropriate anion. From the values of vCO for this series can be gained some understanding of the bonding properties of the anionic ligands.