A monitor for atmospheric sulphur dioxide,based on enrichment of SO2 by a polydispersive water aerosol

A monitor for continuous analysis of sulphur dioxide in the atmosphere at the ppb v/v level (1 ppb v/v = 2.62 g/m³ SO₂) is described. The apparatus operates on the principle of equilibrium accumulation of sulphur dioxide from the air by a polydispersive water aerosol which continuously transfers SO₂ from an air-flow of l/min into microlitre volumes of water condensate. High sensitivity (1 ppb v/v), low relative error (± 5% at 4 ppb v/v SO₂), high selectivity (CO₂ does not interfere at a concentration of 2 × 10³ ppm v/v, interference by NO _x and H₂S is acceptably low), and low response delay (10 s) are provided by a compact coupling of the enrichment procedure with conductivity detection of SO₂ in the film of water aerosol condensate formed directly on the wire-gauze sensor. The reliability of the method has been studied under simulated conditions, with spectrophotometric method as reference. The analyser is computer-controlled, and the detector response is processed on-line and displayed (as g/m³) in real-time on a screen or is transmitted telemetrically to a control centre. It is portable and suitable for use in both stationary and moving locations.The paper is dedicated to the 65th anniversary of the birthday of Prof. Josef F. K. Huber     

Isolation and determination of dissolved organic sulphur compounds — development of the organic group parameter DOS

A procedure has been worked out for the determination of organic sulphur compounds (OSCs) in aqueous solution. They are isolated from water by solid phase extraction on macroporous resins and reversed-phase sorbents. The total sulphur content of the extracts is determined via a process of thermal cracking and hydrogenation (pyrohydrogenolysis) of small amounts of extract in a heated quartz tube (1100°C) flushed with hydrogen. Sulphur is detected at a wavelength of 394 nm in the hydrogen flame of a flame photometer. The flame photometric detector (FPD) is calibrated with a coulometric H₂S-generator. The procedure of solid phase extraction and subsequent pyrohydrogenolysis/flame photometry of the extracts can be used to determine the organic group parameter DOS (Dissolved Organic Sulphur) in the range of 20–1000 μg/1.     

Isolation and determination of dissolved organic sulphur compounds — development of the organic group parameter DOS

A procedure has been worked out for the determination of organic sulphur compounds (OSCs) in aqueous solution. They are isolated from water by solid phase extraction on macroporous resins and reversed-phase sorbents. The total sulphur content of the extracts is determined via a process of thermal cracking and hydrogenation (pyrohydrogenolysis) of small amounts of extract in a heated quartz tube (1100° C) flushed with hydrogen. Sulphur is detected at a wavelength of 394 nm in the hydrogen flame of a flame photometer. The flame photometric detector (FPD) is calibrated with a coulometric H₂S-generator. The procedure of solid phase extraction and subsequent pyrohydrogenolysis/flame photometry of the extracts can be used to determine the organic group parameter DOS (Dissolved Organic Sulphur) in the range of 20– 1000 μg/l. Received: 12 March 1996 / Revised: 25 April 1996 / Accepted: 30 April 1996     

Bestimmung von Schwefel in verschiedenen Oxydationsstufen in Papieren und Fasern auf Cellulosebasis

Zusammenfassung In dieser Arbeit wurde die quantitative Analyse von Schwefelverbindungen in Papieren und Cellulosefasern untersucht. Mittels einer selbst entwickelten Apparatur ist es möglich, Sulfid, Sulfit, Sulfat sowie elementaren Schwefel nebeneinander im Mikrogramm-Bereich zu bestimmen. Es konnten 10^–6 der aufgeführten Schwefelverbindungen pro Gramm Papier quantitativ bestimmt werden. Außerdem wurde eine Methode zur Ermittlung des Gesamtschwefels ausgearbeitet. Die angegebenen Methoden lassen sich prinzipiell zur Bestimmung der aufgeführten Schwefelverbindungen in organischen und anorganischen Substanzen verwenden.

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Summary A method has been developed for the determination of sulphur compounds in papers and cellulose fibres. With the apparatus described sulphide, sulphite, sulphate and elementary sulphur can be selectively determined in gconcentrations. The authors were able to determine quantitatively 10^–6 g of the above sulphur compounds per one gram of paper. In addition a procedure has been worked out for the determination of total sulphur. These methods can also be applied for sulphur determinations in other organic and inorganic substances.

     

PbMn(SO4)2: A new chiral antiferromagnet

PbMn(SO₄)₂ has been synthesized in an evacuated quartz tube. The nuclear and magnetic crystal structures have been determined using powder X-ray and neutron diffraction. This material crystallizes in the enantiomorphic space group pair P4₁2₁2(92) and P4₃2₁2(96), forming a double-helical arrangement of Pb²⁺ and Mn²⁺ cations. The Mn²⁺O₆ octahedra are distorted. Each 3d⁵ Mn²⁺ has four nearest-neighbors and four next-nearest-neighbors adopting a frustrating arrangement. The compound orders antiferromagnetically at 5.5 K. Field dependent specific heat and magnetization measurements show that T_N is suppressed to 3.3 K when μ₀H=9 T.     

Dimethyl telluride as a ligand: synthesis and physicochemical studies on its complexes with transition metal bis(chlorosulphates) M(SO3Cl)2(M=Cr,Mn, Fe,Co, Ni,Cu)

Summary Dimethyl telluride, Me₂Te, reacts with first row transition metal bis(chlorosulphates), M(SO₃Cl)₂(M=Cr^II, Mn^II, Fe^II, Co^II, Ni^II, Cu^II) in MeCN resulting in the formation of compounds of the type [M(SO₃Cl)₂-(Me₂Te)₂]. These compounds are stable under N₂ but decompose on exposure to moist air. The covalent nature of bonding of the SO₃Cl^– group has been ascertained on the basis of a positive shift in ₁ (A) vibration, splitting of the doubly degenerate (E) modes and low molar conductivity values. The magnetic moments and electronic spectra suggest an octahedral geometry for these compounds (except for the Ni^II complex where a tetragonal distortion is observed) where each SO₃Cl^– group is bonded in a bidentate manner.     

The AMn5(SO4)6 family of triangular lattice, ferrimagnetic sulfates

A new family of anhydrous sulfates, A²⁺Mn₅(SO₄)₆ (A=Pb, Ba, Sr) is reported. The crystal structures of PbMn₅(SO₄)₆ and SrMn₅(SO₄)₆ are solved by powder X-ray and neutron diffraction. BaMn₅(SO₄)₆ is isostructural. PbMn₅(SO₄)₆ crystallizes with symmetry and unit cell parameters of a=14.551(1) Å and c=7.535(1) Å. The structure has rich features, including dimers of face-sharing MnO₆ octahedra, and two complementary triangular layers of Mn atoms. All compounds undergo a magnetic ordering transition at 10 K, below which, the magnetic susceptibility of the compounds varies systematically with the radius of the non-magnetic cation. Low temperature neutron diffraction shows that the complementary triangular layers result in a ferrimagnet with a net moment corresponding to one high spin Mn²⁺ per unit cell, correlating well with the magnetization data. The non-magnetic variant PbMg₅(SO₄)₆ is also reported.     

The crystal and molecular structure oftrans-Di(methylsulphito)bis-(triphenylphosphine)platinum(II)

Summary The crystal and molecular structure oftrans-di(methylsulphito)bis(triphenylphosphine)platinum(II), Pt(SO₃Me)₂ (PPh₃)₂, derived from the reaction of Pt(PPh₃)₂ (O₂) with SO₂ in MeOH and in the presence of sodium tetraphenylborate(III), has been determined from diffractometer data. The complex crystallizes in the space group P ¯1- (C_i ¹) with one molecule in a unit cell of dimensionsa = 9.744(2) Å,b = 10.062(3) Å,c = 11.153(2) Å; = 68.59(2)°, = 82.69(2)° and = 62.25(2)°. Leastsquares refinement has led to a value of the conventional R index (on F) of 0.031 for the 3308 reflections having F²>3(F₀ ²). The complex is a typical square-planar platinum(II) complex with the platinum atom lying on a crystallographically imposed centre of symmetry. The important structural parameters are Pt-P 2.369(1) Å, Pt-S 2.308(1) Å, and the oxygen atoms complete an approximate tetrahedron about the sulphur atoms with S-O 1.448(5) Å and S-O(Me) 1.620(5) Å.     

Entrapping of Push-Pull Zwitterionic Chromophores in Hybrid Matrices for Photonic Applications

A new class of heterocycle-based push-pull chromophores showing enhanced nonlinear properties characterized by an aromatic and highly zwitterionic ground state and a quinoid/neutral excited state have been synthesized to be incorporated in sol-gel hybrid systems. This class of compounds shows very large first molecular hyperpolarizabilities ( as high as 27000 × 10^–48 esu) and is a promising candidate for photonic applications where large second order non-linearities are required. In spite of their very large hyperpolarizability and chemical and thermal stability, these chromophores are decomposed in presence of light and oxygen (photobleaching) and are sensitive to acidic environments due to the carbanionic nature of the donor moiety. A hybrid matrix, based on N-[(3-trimethoxysilyl)propyl]ethylenediamine and 3-glycidoxypropyltrimethoxysilane, has been specifically designed to allow the incorporation of such zwitterionic compounds assuring at the same time a good temporal stability of the optical properties. Amine functionalisation has been found very effective in reducing the photobleaching by acting on these chromophores via the singlet oxygen. Second harmonic generation has been observed on poled films, and an order parameter, , of 0.17 has been estimated. The nonlinear coefficient d_eff of the samples has been thus estimated at a value two times larger than for d₁₁ of quartz that, from literature data, is about 0.335 pm/V.     

Entwässerung von Kristallhydraten als Verfahren zur Reinigung von Salzen, 3. Mitt.: Entwässerung von Na2SO4·10H2O in gesättigter Lösung bei der Temperatur des Übergangs

Zusammenfassung Das Verhalten einer nicht-isomorphen Beimengung bei der Entwässerung von Na₂SO₄·10H₂O bis zum wasserfreien Salz in gesätt. Lösung bei der Temp. des Übergangs wurde untersucht. Es wurde festgestellt, daß der Entwässerungsprozeß von einem Prozeß der Beimengungsverminderung begleitet wird. Dabei wird bei der Re-Hydratisierung des Na₂SO₄ bis zu Na₂SO₄·10 H₂O die Beimengung wieder eingeschlossen. Bei einem geringeren Gehalt an Beimengung in Na₂SO₄·10 H₂O ist der Reinigungseffekt beim Entwässerungsprozeß kleiner und umgekehrt. In der Reihe Cl, Br, J wird — bei sonst gleichen Bedingungen — J am schwierigsten beseitigt, Cl am leichtesten. Außerdem ist die Abhängigkeit zwischen dem Reinigungseffekt (ausgedrückt durch den Reinigungskoeffizienten,W) und dem Ionenradius linear. Die Wasserstoffionenkonzentration in der gesättigten Na₂SO₄·10 H₂O-Lösung übt keinen wesentlichen Einfluß auf die Beseitigung der Beimengung aus.

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Purification of salts by dehydration of crystal hydrates, III: Dehydration of Na₂SO₄·10 H₂O in saturated solution at the transition temperature

The behaviour of a non-isomorphous admixture in the dehydration of Na₂SO₄·10 H₂O to the anhydrous salt in a saturated solution at the transition temperature has been investigated. It was found that a decrease of admixture accompanies the dehydration process. The admixture is reincluded during rehydration of Na₂SO₄ to Na₂SO₄·10 H₂O. With a lower admixture content, the purification achieved during dehydration of Na₂SO₄·10 H₂O is less marked, and vice versa. In the series Cl, Br, I, other conditions being equal, I is hardest to remove, Cl easiest. It was further found that a linear relationship exists between the purifying effect (expressed by the purification coefficient,W) and the ion radius. The hydrogen ion concentration has no significant influence on the removal of the admixture.

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Mit 6 Abbildungen     

Zur analytischen Verwendung von S-Methylisothiuroniumsulfat bei der Mercaptanbestimmung

Zusammenfassung Zur Vermeidung der Schwierigkeiten, die bei der Eichung in der polarographischen Mercaptananalyse auftreten, wurde ein Verfahren ausgearbeitet, das für die Bestimmung der Summe von Methyl- und Äthylmercaptan den Gebrauch von S-Methylisothiuroniumsulfat [(S-MIT)₂SO₄] und seine alkalische Zersetzung zu Methylmercaptan unmittelbar vor Gebrauch in der polarographischen Zelle vorschlägt. Untersuchungen über die Bestän-digkeit wäßriger Lösungen von (S-MIT)₂SO₄ ergaben, daß 0,001 M Lösungen bis zu pH 3 über 134 Tage unveränderlich sind. Das beständige und völlig geruchlose (S-MIT)₂SO₄ kann direkt als Urtitersubstanz für Methylmercaptan eingewogen werden. — Durch ac-Polarographie konnten Eichkurven bis zu einem Gehalt von 3 · 10^–6 Mol CH₃SH/l aufgestellt werden.Weiterhin wurde die Eignung des (S-MIT)₂SO₄ als Titrationsmittel zur amperometrischen Bestimmung des Quecksilbers im Mikrogramm-Bereich mit der vibrierenden Platinelektrode gezeigt. Die indirekte Anwendung dieser Methode erlaubt eine schnelle Bestimmung von Mercaptanen und Sulfid im Mikrogramm-Bereich (durchschnittlicher relativer Fehler 5%). Durch die Fällung der entsprechenden Quecksilbersalze sind durch Luftoxydation entstehende Verluste dieser Verbindungen zu vermeiden. Die Methode wurde angewendet zur Gehaltsbestimmung von Sulfideichlösungen und zur H₂S-Bestimmung in Gasen.

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Summary A procedure has been worked out for the improvement of the calibration in polarographic mercaptan analysis. For calibration in the determination of the sum of methyl- and ethylmercaptan use is made of the alkaline decomposition of S-methylisothiuronium sulphate [(S-MIT)₂SO₄] to methylmercaptan immediately before use in the polarographic cell. The stability of aqueous solutions of (S-MIT)₂SO₄ has been examined at different pH-values over 134 days and it has been shown that 0.001 M solutions are stable up to pH 3. The stable and odourless substance can be directly weighed as a primary standard for methylmercaptan. By a c-polarography calibration curves were obtained up to a concentration of 3×10^–6 Mole of CH₃SH/l.Furthermore it is shown that (S-MIT)₂SO₄ can be employed as titrant for the amperometric determination of mercury in the g range using the vibrating Pt electrode. By indirect application of this method mercaptans and sulphide can be determined quickly and exactly with an average relative error of 5%. The method was applied to the determination of the content of sulphide standard solutions and of hydrogen sulphide in gases.

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Diese Arbeit wurde im Rahmen, einer Vertragsforschung mit dem VEB Leuria-Werke Walter Ulbricht durchgeführt. Wir danken dem Werk für die Bereitstellung von Mitteln.     

The double salts M3RE(SO4)3 (M=K,Rb) with framework structures

The crystal structures of K₃Er(SO₄)₃ [space group Pc, a=9.222(2), b=14.688(1), c=9.008(1) Å, =110.72(2)^o, Z=4, R=0.59] and of Rb₃Tm(SO₄)₃ [space group Cc, a=10.649(2), b=15.149(3), c=9.320(2) Å, =124.49(1)^o, Z=4, R=0.043] have been studied (CAD-4 diffractometer, Mo radiation). It has been shown that the compounds K₃RE(SO₄)₃ (RE=Nd–Er) and Rb₃RE(SO₄)₃ (RE=Tm–Lu), which crystallize in accordance with these structural types, form a family of framework structures with a single basis. The relationship between their structure and the structure of the rhombohedral compounds M₃M^III(SO₄)₃ (M^III=Al, Ga, In) and Cs₃Yb(SO₄)₃ has been examined.Scientific-Research Institute of Chemical Reagents and Ultrapure Chemical Substances. Translated from Zhurnal Strukturnoi Khimii, Vol. 32, No. 2, pp. 110–115, March–April, 1991.     

The titrimetric micro determination of sulphate using lead nitrate as titrant and dithizone as indicator

Summary The previously reported titrimetric determination of sulphate, using lead nitrate as titrant and dithizone as indicator has been developed for application to the micro scale. Attention has been directed in the titration procedure to the effect of foreign ions and their removal where necessary, the optimum conditions for the highest accuracy, and the precision attainable for the range 0.5 to 5 mg of sulphate (0.16 to 1.6 mg of sulphur). This procedure forms a highly satisf actor y basis for the micro determination of sulphur in organic compounds by oxidation with nitric acid in a sealed tube and subsequent titration of the sulphate ion produced.The procedure has also been extended to the submicro scale giving a direct titration of 10 to 100g of sulphate (4–30g of sulphur), thus enabling the sulphur content of submicro quantities of organic compounds to be readily determined.

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Zusammenfassung Die kürzlich veröffentlichte Methode der maßanalytischen Schwefelbestimmung mit Bleinitrat unter Verwendung von Dithizon als Indikator wurde dem Mikromaßstab angepaßt. Auf die Störung durch Fremdionen und deren gegebenenfalls notwendige Entfernung wurde Bedacht genommen, die optimalen Bedingungen für größte Genauigkeit für den Bereich von 0,5 bis 5 mg Sulfat (0,16 bis 1,6 mg Schwefel) ermittelt. Das Verfahren bietet einen sehr befriedigenden Weg für die Mikrobestimmung des Schwefels in organischen Substanzen durch deren Oxydation mit Salpetersäure im geschlossenen Rohr und nachfolgende Titration des Sulfats.

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Rèsumè La méthode précédemment décrite pour le dosage titrimétrique des sulfates à l'aide de nitrate de plomb comme réactif titrant et de dithizone comme indicateur a été étendue au domaine microanalytique. La technique de titrage a été particulièrement étudiée des points de vue de l'effet des ions étrangers et de l'éventuelle nécessité de leur élimination, des conditions optimum pour atteindre l'exactitude la plus élevée et pour déterminer la précision qu'il était possible d'obtenir pour le domaine de 0,5 à 5,0 mg de sulfate (0,16 à 1,6 mg de soufre). Cette technique est extrêmement satisfaisante pour son application au microdosage du soufre dans les composés organiques après oxydation par l'acide nitrique en tube scellé et titrage ultérieur de l'ion sulfurique formé.

     

Continuous flow thin layer headspace (TLHS) analysis

Summary The paper presents a new method of a continuous isolation and determination of volatile organic halogens (VOX) in drinking waters based on so-called thin layer headspace (TLHS) isolation technique. The liberated volatile compounds are mineralized in an empty quartz tube at 850°C and absorbed in a buffered washing solution. After separation of air the halogen ions are determined potentiometrically in a flow-through cell using a silver/silver choride indicating electrode. The potential of the electrode is a linear function of the halogen ion concentration in the washing solution within the VOX concentration range usually encountered in drinking waters. The estimated detection limit of the method is ca. 0.1 g/l VOX and can be further improved by increasing the concentration factor. The theory of the TLHS isolation method has been further developed and verified. The derived dependences enable a simultaneous determination of the effective partition coefficients in the system, thus enabling calculation of the optimal gas flow rate.Part I and II, see [1, 2]     

Spectrographic determination of trace impurities in sulphur

Summary An emission spectrographic method for the estimation of traces of some common impurites viz., Al, Ba, Bi, Ca, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sn, Ti and V in high-purity sulphur is described. The impurities separated from 1-g sample, after removing sulphur as SO₂ by heating it in air at about 300° C, were dissolved in a small amount of 6M hydrochloric acid and loaded on 10 mg of carrier mixture containing 90% graphite and 10% sodium chloride in the 1/4 electrode crater. The spectra were exited in a D. C. arc carrying 13 A current for 45 seconds. Cobalt was used as an internal standard and sodium chloride as a carrier. The lowest detection limits lie in the range 0.005 to 0.05 ppm for the different elements. The precision of the method ranges from 6–19% for the elements analysed.

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Zusammenfassung Eine emissionsspektrographische Methode zur Bestimmung üblicher Spuren-Verunreinigungen in hochgereinigtem Schwefel, wie Al, Ba, Bi, Ca, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sn, Ti und V, wurde beschrieben. Die aus 1 g Schwefel, nach dessen Entfernung als SO₂ durch Erhitzen an der Luft bei etwa 300° C, abgetrennten Verunreinigungen werden in wenig 6-m Salzsäure gelöst und mit 10 mg Trägergemisch, bestehend aus 90% Graphitpulver mit 10% Natriumchlorid, in die Vertiefung einer 1/4-Elektrode eingebracht. Das Spektrum wird im Wechselstrombogen von 13 A für 45 sec angeregt. Kobalt dient als interner Standard mit Kochsalz als Träger. Die unterste Nachweisgrenze liegt bei 0,005–0,05 ppm für die verschiedenen angegebenen Elemente. Die Genauigkeit beträgt 6–19%.

     

Simultaneous C-H-N and S microdetermination by combustion and gas chromatography

Summary A method based on flash-combustion of the sample in a flow of temporarely oxygen-enriched helium, catalytic oxidation and reduction of the combustion gases within the same reactor, gas-chrom- matographic separation and thermal-conductivity detection of the end-products, has been developed in order to determine C-H-N-S simultaneously in organic and inorganic substances, with a 0.1–2 mg sample. To develop this method, optimization of analytical parameters was necessary because of the chemical and physical behaviour of oxides of sulphur in the analyser. Therefore flashcombustion in a tin container, use of a tungstic oxide oxidative layer close to a copper reductive layer, setting the copper temperature at 850° C and selective halogen adsorption are the main features. The temperature of 850° C for the copper gives a quantitative yield of SO₂ in spite of the reaction between sulphur oxides and cupric oxide, and also gives quantitative reduction of the nitrogen oxides. The individual components of the combustion mixture are separated by means of a Porapak QS column and detected in the sequence Na, CO₂, H₂O and SO₂, the signals being automatically integrated and printed. Detector response for SO₂ is linear from someg up to 10 mg.

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Zusammenfassung Zur gleichzeitigen Bestimmung von C, H, N und S in 0,1 bis 2 mg anorganischer oder organischer Substanz wurde ein Verfahren entwickelt, wobei die Substanz in zeitweilig sauerstoff-angereichertem Helium verbrannt, die Verbrennungsprodukte im selben Reaktionsrohr zunächst katalytisch oxydiert, dann reduziert werden. Anschließend werden die Endprodukte gas-chromatographisch getrennt und mittels Wärmeleitfähigkeitsmessung bestimmt. Zur Entwicklung dieses Verfahrens mußten die analytischen Parameter wegen des chemischen und physikalischen Verhaltens der Schwefeloxide optimiert werden. Daher werden Flammenverbrennung in einem Zinngefäß, Verwendung von Wolframoxid als oxydierende Schicht unmittelbar neben Kupfer als reduzierender Schicht, die auf 850° C gehalten wird, sowie selektive Adsorption der Halogene als wichtigste Schritte betrachtet. Die Temperatur von 850° C gewährleistet quantitative Ausbeute an SO₂ im Gegensatz zur Reaktion zwischen Schwefeloxiden und Kupferoxid und führt auch zur quantitativen Reduktion der Stickstoffoxide. Die einzelnen Teile des Verbrennungsgemisches werden mit einer Säule aus Porapak QS getrennt und in der Reihenfolge N₂, CO₂, H₂O und SO₂ nachgewiesen, wobei die Signale automatisch integriert und gedruckt werden. Der Detektorausschlag für SO₂ ist von einigen Mikrogramm bis 10 mg linear.

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Dedicated to Prof. H. Lieb for his 90th birthday.

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Presented at the International Symposium on Microchemical Techniques, May 23–27, 1977, Davos, Switzerland.     

Determination of Total Organic Sulfur in Petroleum Products

A procedure was proposed for determining total organic sulfur in petroleum products. The procedure involves the exhaustive hydrogenolysis of sulfur-containing compounds in an autonomous quartz flow reactor under a hydrogen atmosphere at 1000 ± 50°C with the trapping of the hydrogen sulfide formed in an aqueous solution of an alkali followed by the gas-chromatographic determination of H₂S in the trapping solution using dynamic reaction gas extraction and selective flame-photometric detection. The determination limit was 0.01 wt % for sample volumes below 30 L; the relative standard deviation was 7% on average.     

The crystal and molecular structure of bis{−(μ-sulphato-O′-O′-O″)bis (triphenylphosphine) (sulphurdioxide)ruthenium(II)}} · (toluene) [Ru(SO4)(SO2)(PPh3)2]2 · (C7H8)

Summary The preparation and structure of the title compound, [Ru(SO₄)(SO₂)(PPh₃)₂]₂, is reported. The compound is formed in low yield when SO₂ is passed through a solution of RuH₂(PPh₃)₄ in toluene. The structure has been determined using diffractometer data and refined by least-squares techniques to R=0.078 based on 2669 observed intensities. The crystals are orthorhombic, Pbca (D _2h ¹⁵ ), with unit cell dimensionsa=17.635(7) Å,b=18.874(7) Å,c=21.631(7) Å; Z=4. The coordination geometry about the ruthenium is a distorted octahedron with the triphenylphosphine ligands occupyingcis-coordination sites. The sulphato group is bidentate with respect to any particular metal atom, and additionally utilises a third oxygen atom to link two coordination centres to give a dimeric structure. The remaining coordination site is occupied by a sulphur dioxide ligand bonded in a ¹-planar coordination mode with Ru-S equal to 2.107(5) Å. This crystal structure analysis has assisted in formulating the primary product of the reaction of SO₂ with RuH₂ (PPh₃)₄ as Ru(SO₄)(SO₂)(PPh₃)₂(H₂O).     

Synthesis, structural characterisation and thermal decomposition studies of some 2,4′-bipyridyl complexes with cobalt(II), nickel(II) and copper(II)

2,4-Bipyridyl (2,4-bipy orL) complexes with cobalt(II), nickel(II) and copper(II) of the formulae M(2,4-bipy)₂(CH₃COO)₂·2H₂O (M(II) = Co, Ni, Cu), Co(2,4-bipy)₂SO₄·3H₂O or Ni(2,4-bipy)₂SO₄·4H₂O have been prepared and their IR and electronic (VIS) spectra are discussed. The thermal behaviour of the obtained compounds has also been studied. The intermediate products of decomposition at different temperatures have been characterized by chemical analysis and X-ray diffraction.We thank dr. A. Malinowska for performing VIS spectra. This work was supported by the KBN project No. PB 0636/P3/93/04.