APCI Mass Spectrometry Research Articles

What is the advantage of alternative current (AC) corona discharge for APCI mass spectrometry?

A comparative study on direct current (DC) and alternating current (AC) corona discharge ionization for positive and negative mode of operation was performed by mass spectrometry. The needle, positioned 3 mm in front of the inlet of a mass spectrometer, was moved upward and intensities of ions were measured as a function of vertical distance d. For DC corona discharge, the unipolar plasma sizes for positive and negative ions were found to be nearly the same with d ≈ ∼5 mm. In contrast, for AC corona with 15 kHz, while positive ions were found to be much more confined in a narrow region with d ≈ ∼2 mm, negative ions were detected with much larger d ≈ ∼10 mm. This marked difference of unipolar plasma sizes of positive and negative ions for AC corona was ascribed to the much larger diffusion lengths of electrons than those of positive ions. In the negative mode of DC and AC corona discharge ionization, the intensity of CH3COO− (m/z 59) originating from an acetic acid impurity was found to increase with d. This peculiar behavior was attributed to the proton transfer reaction of O2− with acetic acid vapor taking place distant from the tip of the electrode needle. The ionization efficiency of AC corona is higher than that of DC corona for both positive and negative modes of operation. The higher ionization efficiencies for AC corona are attributed to the generation of remnant electrons and positive ions for positive and negative phase AC corona, respectively. These remnant charges play crucial roles as the triggers for plasma breakdown in every cycle of RF frequency. The ion intensities measured by proximity corona discharge ionization are almost proportional to the analyte concentrations when they are less than 1 ppm.

A mass spectrometric stochastic dynamic diffusion approach to selective quantitative and 3D structural analyses of native cyclodextrins by electrospray ionization and atmospheric pressure chemical ionization methods

The paper addressed shortcoming with highly precise and selective 3D structural analysis of native cyclodextrins in mixture using ions observable at low m/z–region by ESI– and APCI–mass spectrometry. Because of, the quantitative and structural analyses of CDs, in general, are vexed by a set of complications. The study outlines our own stochastic dynamic approaches to the latter issues based on new model relations, quantifing the measurable MS outcome intensity. They introduce the so–called stochastic dynamic mass spectrometric diffusion “DSD” parameter, exhibiting high accuracy, precision, sensitivity and selectivity, respectively. It is linearly connected with the so–called quantum chemical diffusion parameter “DQC” according to Arrhenius’s theory. The most important upshot is that statistical parameters r = 0.99639–0.99981 has been obtained correlating between DSD and DQC parameters. Therefore, we determine high accurately 3D molecular and electronic structures of analytes by mass spectrometry. Fragment peaks at m/z 313, 279, 272, 252, 231, 214, 198, 171, 158 and 141 are examined. Mixtures of CDs and monomeric and acyclic oligomer carbohydrates glucose (1), sucrose (2), raffinose (3), melezitose (4) and cellotriose (5) are also studied. Our method is able to account precisely for the effect of the temperature under ESI– and APCI–MS conditions, as well. Correlative analysess between DSD parameters of ESI– and APCI–MS measurements under different temperatures is also shown. Chemometric tests are used. Another important results and conclusions, among others, to draw from this research are: (i) excellent linear correlation between DSD and DQC parameters of r = 0.99636 is found looking at common ions at m/z 141, 158 and 171, belonging to 2-formyl-3,4-dihydroxy-pyranylium, 4,5,6-trihydroxy-6H-pyran-2-carbaldehyde and 3,4,5-trihydroxy-6-oxo-6H-pyran-2-ylmethylidyne-oxonium ions. Thus, we distinguish precisely between the last structure and 3-formyl-4,5-dihydroxy-2,7-dioxa-8-oxonia-bicyclo[4.2.0]octa-1(8),3,5-triene cation. In the case of ion at m/z 141 subtle electronic effects are distinguished between the mentioned structure and the charged 3,4-dihydroxy-6H-pyran-2-carbaldehyde one. The method determines precisely very similar structurally poly–OH–substituted derivatives. Because of, (ii) absolute reproducibility (r = 1) of DSD parameters of ESI–MS spectra is obtained studying the shown in point (i) MS peaks of β-CD between jth and jth numbers of experiments. The statistical equation is DiSD = (0.51 ± 3.1.10−5) × DjSD; (iii) the APCI– and ESI–MS provide identical results studying common MS ions of CDs and the correlation between DAPCISD and DESISD parameters excludes from error, due to, experiment; and (iv) The correlation between theory and experiment accounting for the factor temperature within our model equations shows r = 0.9828 looking at the MS peaks at m/z 313 280, 279, 274 and 252, respectively. The effect of the temperature under both ESI– and APCI–MS conditions on the 3D molecular and electronic structures of CDs is precisely studied, respectively.

Mechanism investigation of HS radical and CS losses from positively charged biradicals of diphenyl sulfides by APCI mass spectrometry.

Aryl thioethers are potentially useful precursors for constructing various biologically active sulfur-containing heterocycles. The detailed relationship between the losses of HS radical and CS with the spin multiplicity of positively charged diphenyl sulfide biradicals derived from 3-iodophenyl phenyl sulfides has not been obtained by tandem mass spectrometry combined with theoretical calculations. Collision-induced dissociation mass spectrometry experiments were carried out using an ion trap mass spectrometer with APCI in positive mode. The MS/MS experiment for dibenzothiophene was performed by CI triple-quadrupole mass spectrometry in positive ion mode. The accurate masses of fragments were obtained by reflective TOFMS with an EI source. Theoretical calculations were achieved by the density functional theory method at the B3LYP level with the 6-31+G(d, p) basis set in the Gaussian 03 package of programs. In the fragmentation of positively charged diphenyl sulfide biradicals, losses of HS· and CS were observed, which were proposed to originate from spin multiplicity transformation from a triplet ground state to a singlet excited state and a phenyl radical shift in triplet ground state, respectively. Moreover, a protonated dibenzothiophene intermediate was confirmed to exist in the process of HS radical loss. A linear correlation was established between the product ion abundance from the two competitive losses and the Hammett constants (σ) of substituent groups on the benzene ring. The eliminations of HS· and CS in the fragmentation of positively charged diphenyl sulfide biradicals were triggered by spin multiplicity transformation from a triplet ground state to a singlet excited state and a phenyl radical shift in a triplet ground state, respectively. Based on theoretical calculations, two competitive neutral losses are thermodynamically controlled. Copyright © 2016 John Wiley & Sons, Ltd.

Coupling ferrocene to brominated tetraazaporphyrin: exploring an alternative synthetic pathway for preparation of ferrocene-containing tetraazaporphyrins

A Castro--Stephens coupling reaction between metal-free 3(2),8(7)-dibromo- 2(3),7(8),12(13),17(18)-tetra-tert-butyl-5,10,15,20-tetraazaporphyrin and (ferrocenylethynyl)copper resulted in the formation of copper 2(3),7(8),12(13), 17(18)-tetra-tert-butyl-3(2), 8(7)-di(ferrocenylethynyl)-5,10,15,20-tetraazaporphyrin and copper 2(3),7(8),12(13),17(18)-tetra-tert-butyl-3(2)-ferrocenylethynyl-5, 10,15,20-tetraazaporphyrin, which were separated in the form of 2 positional isomers along with copper 3(2)-bromo-2(3),7(8),12(13),17(18)-tetra-tert-butyl-5,10,15,20-tetraazaporphyrin and copper 2(3),7(8),12(13),17(18)-tetra-tert-butyl-5,10,15,20-tetraazaporphyrin. A similar reaction with metal-free 3(2),8(7),13(12), 18(17)-tetrabromo-2(3),7(8),12(13),17(18)-tetra-tert-butyl-5,10,15,20-tetraazaporphyrin resulted in only a trace amount of 3(2),8(7),13(12)-tribromo-2(3),7(8),12(13),17(18)-tetra-tert-butyl-18(17) -ferrocenylethynyl-5,10,15,20-tetraazaporphyrin, while no products with larger number of organometallic substituents were observed. Direct coupling between ferrocenelithium and 3(2),8(7)-dibromo-2(3),7(8),12(13),17(18)-tetra-tert-butyl-5,10,15,20-tetraazaporphyrin resulted in a debromination reaction accompanied by very minor dimerization of the tetraazaporphyrin core, which was explained based on the steric properties of the parent tetraazaporphyrin. The target compounds were characterized using APCI mass spectrometry, UV-vis, and MCD spectroscopy, while the electronic structure of ferrocenylethyl-containing products was predicted by DFT approach. X-ray structures of individual positional isomers of copper 2-bromo-3,7,12,18-tetra-tert-butyl-5,10,15,20-tetraazaporphyrin and 3, 7, 12,18-tetrabromo-2,8,13,17-tetra-tert-butyl-5,10,15,20-tetraazaporphyrin were also discussed.

Rapid separation and characterisation of triacylglycerols in ostrich oil by ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry

The triacylglycerol (TAG) composition of ostrich oil (Struthio camelus) was determined by non-aqueous reversed-phase ultra-performance liquid chromatography–mass spectrometry. Using a column with 150mm in length, the TAGs were separated efficiently with acetonitrile/2-propanol gradient at flow rate of 0.2mL/min for 20min. Detection is performed by positive APCI mass spectrometry, accurate mass measurements (<3ppm) and definite elemental composition for molecular ions and fragment ions were obtained to enable characterisation of 24 TAGs in both ostrich oil and emu oil. In terms of TAGs composition and contents, the ostrich oils are similar to emu oils. This result indicates that the ostrich oil could be a good choice of substitution for emu oil, which is expensive and comparatively rare, in food, dietetics and cosmetics industry.

ESI, APCI, and MALDI tandem mass spectrometry of poly(methyl acrylate)s: A comparison study for the structural characterization of polymers synthesized via CRP techniques and the software application to analyze MS/MS data

Research in polymer science and engineering is moving from classical methodologies to advanced analytical strategies in which mass spectrometry (MS)-based techniques play a crucial role. The molecular complexity of polymers requires new characterization tools and approaches to elucidate the detailed structural information. In this contribution, a comparison study of poly(methyl acrylate)s (PMA) using different tandem mass spectrometry techniques (ESI, APCI, and MALDI MS/MS) is reported to provide insights into the macromolecular structure with the aid of a special MS/MS data interpretation software. Collision-induced dissociation (CID) was utilized to examine the fragmentation pathways of PMAs synthesized via various controlled radical polymerization techniques. All three mass spectrometry techniques are used to analyze structural details of PMAs and the labile end-groups are determined based on the fragmentation behavior in CID. Fragmentation products were identified which are characteristics for the cleavage between the polymer chain and the end-group. The application of a tailor-made software is shown to analyze complex MS/MS data, and it is proven that this kind of software will be helpful for polymer scientists to identify fragmentation products obtained by tandem mass spectrometry similar to the fields of proteomics, metabolomics, genomics, and glycomics. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

Exploring suitable oligoamines for phantom ring-closing condensation polymerization with guanidine hydrochloride

Different model compounds were applied in step-growth condensation reactions with guanidine hydrochloride in order to explore the scope of tri- and oligoamine applicability for phantom ring-closing condensation polymerization processes. The selective formation of five-membered rings was proven by APCI mass spectrometry, different one- and two-dimensional homo- and heteronuclear coupling NMR techniques and investigated via quantum chemical calculations. Furthermore the possibility of ring-closing reactions among guanidine hydrochloride and merely secondary amines was precluded. The obtained oligomers were exposed to antibacterial tests and exhibited a moderate activity towards Escherichia coli.

Oxidation Mechanisms of CF2Br2and CH2Br2Induced by Air Nonthermal Plasma

Oxidation mechanisms in air nonthermal plasma (NTP) at room temperature and atmospheric pressure were investigated in a corona reactor energized by +dc, -dc, or +pulsed high voltage.. The two bromomethanes CF(2)Br(2) and CH(2)Br(2) were chosen as model organic pollutants because of their very different reactivities with OH radicals. Thus, they served as useful mechanistic probes: they respond differently to the presence of humidity in the air and give different products. By FT-IR analysis of the postdischarge gas the following products were detected and quantified: CO(2) and CO in the case of CH(2)Br(2), CO(2) and F(2)C ═ O in the case of CF(2)Br(2). F(2)C ═ O is a long-lived oxidation intermediate due to its low reactivity with atmospheric radicals. It is however removed from the NTP processed gas by passage through a water scrubber resulting in hydrolysis to CO(2) and HF. Other noncarbon containing products of the discharge were also monitored by FT-IR analysis, including HNO(3) and N(2)O. Ozone, an important product of air NTP, was never detected in experiments with CF(2)Br(2) and CH(2)Br(2) because of the highly efficient ozone depleting cycles catalyzed by BrOx species formed from the bromomethanes. It is concluded that, regardless of the type of corona applied, CF(2)Br(2) reacts in air NTP via a common intermediate, the CF(2)Br radical. The possible reactions leading to this radical are discussed, including, for -dc activation, charge exchange with O(2)(-), a species detected by APCI mass spectrometry.

Soluble Chlorofullerenes C60Cl2,4,6,8,10. Synthesis, Purification, Compositional Analysis, Stability, and Experimental/Theoretical Structure Elucidation, Including the X-ray Structure of C1-C60Cl10

The efficacy of various analytical techniques for the characterization of products of C(60) chlorination reactions were evaluated by (i) using samples of C(60)Cl(6) of known purity and (ii) repeating a number of literature syntheses reported to yield pure C(60)Cl(n) compounds. The techniques were NMR, UV-vis, IR, and Raman spectroscopy, FAB, MALDI, LDI, ESI, and APCI mass spectrometry, HPLC, TGA, elemental analysis, and single-crystal X-ray diffraction. Most of these techniques are shown to give ambiguous or erroneous results, calling into question the composition and/or purity of nearly all C(60)Cl(n) compounds reported to date. The optimum analytical method for chlorofullerenes was found to be a combination of HPLC and either MALDI or APCI mass spectrometry. For the first time, the chlorination of C(60) by ICl, ICl(3), and Cl(2) was studied in detail using dynamic HPLC analysis and APCI mass spectrometry. Suitable conditions were found for the preparation of the new chlorofullerenes 1,7-C(60)Cl(2), 1,9-C(60)Cl(2), 1,6,9,18-C(60)Cl(4), and 1,2,7,10,14,24,25,28,29,31-C(60)Cl(10). The latter compound was also studied by (13)C NMR spectroscopy and X-ray diffraction, which led to the unambiguous determination of its asymmetric addition pattern. The unusual structure of C(60)Cl(10) was compared with other possible isomers using DFT-predicted relative energies. These results, along with additional experimental data and an analysis of the DFT-predicted frontier orbitals of likely intermediates, were used to rationalize the formation of the new compound C(60)Cl(10) from C(60)Cl(6) and excess ICl without the rearrangement of any C-Cl bonds. For the first time, the stability of C(60)Cl(n) compounds under a variety of conditions was studied in detail, leading to the discovery that they are, in general, very light-sensitive in solution. The X-ray structure of C(60)Cl(6) was also redetermined with higher precision.

Investigation of the Detailed Molecular Structure of the Human Stratum Corneum Ceramides [NP] and [EOS] by APCI and Nano-ESI Mass Spectrometry

Investigation of the Detailed Molecular Structure of the Human Stratum Corneum Ceramides [NP] and [EOS] by APCI and Nano-ESI Mass Spectrometry

DC Corona Electric Discharges for Air Pollution Control, 2—Ionic Intermediates and Mechanisms of Hydrocarbon Processing

AbstractA mechanistic study is reported on i‐octane and hexane processing with +DC and −DC corona in air at room temperature and pressure. Current/voltage profiles are matched with the ion analysis data obtained by APCI mass spectrometry. With a −DC corona, the hydrocarbons do not modify the negative ion population with respect to uncontaminated air. In contrast, with a +DC corona many hydrocarbon‐derived positive ions form. O(3P) and •OH were also investigated using chemical probes (ozone formation and CO oxidation, respectively). The results, combined with efficiency and product data, suggest that with −DC corona radical initiation steps occur, whereas with +DC corona ionic reactions prevail.magnified image

A New Acyclic Diterpene Glycoside from Nicotiana attenuata with a Mild Deterrent Effect on Feeding Manduca sexta Larvae

Abstract To investigate the role of secondary metabolites in the feeding behavior of Manduca sexta larvae feeding on Nicotiana attenuata, an aqueous acetone extract of the aerial parts of the plant was subjected to feeding-performance bioassay-guided fractionation. We isolated three 20- hydroxygeranyllinalool glycosides from the leaves of N. attenuata, which acted as mild deterrents to the feeding herbivore M. sexta. One of the diterpenoid glycosides, attenoside (3), is a novel natural product. The structures of the compounds were determined using APCI mass spectrometry and 1- and 2D-NMR spectroscopy.

Ni(II)-Mediated nitrosation of oximes bearing an α-CH 2 group

Heating of NiCl 2 · 6H 2O with 10-fold excess of an oxime having an α-CH 2 group ( 1– 4) at 100 °C for 1 day in air leads to the formation of the dioxime/ato complexes [Ni(dioxime/ato) 2] ( 5– 8) formed due to a novel type of metal-mediated nitrosation. Compounds 5– 8 were characterized by elemental analyses, FAB ( 5– 7) or APCI ( 8) mass-spectrometry, IR, 1H and 13C{ 1H} spectroscopies (for 8), and X-ray structural study has been performed for 5 and 8; the corresponding ketones ( 9– 12) were identified by LC–MS.

High performance liquid chromatography–mass spectrometry based chemometric characterization of olive oils

In this study the effective discrimination of extra virgin olive oils is described using HPLC–MS, combined with chemometric evaluation. The presented method is simple since the diluted oil sample is directly injected into the system, without any preliminary chemical derivatization or purification step. Separation of diacylglycerols, triacylglycerols and sterols occurs within 20 min and is achieved using an octadecyl-silica column. Detection is performed by positive APCI mass spectrometry which provided sensitivity to detect over 50 compounds in the sample. After extraction of data, stepwise discriminant function analysis is used to select the variables with the highest discriminative power. These variables are used to perform linear discriminant analysis and classify/predict the samples. One-hundred per cent classification and 99% prediction rate was achieved for olive oils obtained from Nocellara, Biancolilla and Cerausola cultivars. Reliability of prediction was tested by cross validation.

Hydrophilic interaction liquid chromatography–APCI–mass spectrometry determination of 5-fluorouracil in plasma and tissues

A simple and fast analytical method using hydrophilic interaction liquid chromatography (HILIC) coupled with mass spectrometry was developed to analyse 5-fluorouracil (5-FU) in plasma and tissues. The HILIC system overcomes problems reported in obtaining satisfactory retention of 5-FU with other types of HPLC systems. After addition of internal standard (IS) (5-Chlorouracil (5-CU)), plasma proteins were precipitated with acetonitrile, and tissue samples homogenised with a micro-dismembrator. The analysis was performed using a polymer-based column (Ashaipak NH 2) and the compounds were eluted under gradient conditions at 1 ml/min using a mobile phase containing a mixture of ammonium formate and acetonitrile. MS detection used a API 4000 mass spectrometry with heated nebulizer source and multiple reaction monitoring operated in the negative ion mode. The mass transitions of 5-FU and its internal standard were 129 m/ z → 42 m/ z and 145 m/ z → 42 m/ z, respectively. The lower limits of quantitation in plasma and tissues were about 5 ng/ml and 10 ng/g, respectively, using 25 μl of plasma and 50 mg of tissue. Good linearity, accuracy and precision were obtained in all matrices tested. The suitability and robustness of the method for in vivo samples were confirmed by analysis of mouse plasma, muscle and tumour from animals dosed with 5-FU.

Modeling the kinetics of flavour release during drinking.

Novel mathematical models for flavour release during drinking are described, based on the physiology of breathing and swallowing. Surprisingly, we conclude that most flavour molecules arriving in the nose are extracted from liquid left in the throat, after swallowing. The models are fit to real time flavour release data obtained using APCI-mass spectrometry. Before modelling, raw data are corrected for the effects of varying airflow rate, using the signal from acetone in exhaled air. A simple equilibrium batch extraction model correctly describes flavour release during the first breaths after swallowing a flavoured liquid. It shows that for eight volatiles, whose in vitro air-water partition coefficients vary by a factor of 500, the apparent in vivo air-saliva partition coefficients vary only by a factor of five. To interpret the kinetics of flavour release longer after swallowing, diffusion of flavour into the throat lining is included. This is done using a three-layer model for mass transfer in the throat. An analytical solution of this model gives good fits to typical data. These models de-couple the physiological and physico-chemical aspects of flavour release, clarifying the effect of behaviour on in-vivo flavour release.

The synthesis, X-ray structures and CVD studies of some group 11 complexes of iminobis(diisopropylphosphine selenides) and their use in the deposition of I/III/VI photovoltaic materials

Reaction of NH(PiPr2)2 with elemental selenium in concentrated solvent conditions enables large scale preparation and improved yields of NH(PSeiPr2)2 that may be deprotonated with sodium methoxide to give NaN(PSeiPr2)2. Treatment of the sodium salt with appropriate Group 11 metal salts in methanol yields a range of trinuclear complexes. The protic solvent conditions utilized facilitate the reduction of copper(II) salts resulting in the isolation of copper(I) complexes. These new Group 11 complexes have been characterised by 1H and 31P NMR and IR spectroscopy, APCI mass spectrometry, microanalysis and X-ray crystallography. Thermolytic decomposition of the copper(I) precursors in the presence of the indium precursor, In[(SePiPr2)2N]2Cl, has been carried in the solid state using AA-MOCVD to give copper indium diselenide solid state materials CuInSe2.

Characterization of methyl methacrylate oligomers using secondary ion mass spectrometry, APCI mass spectrometry and molecular orbital theory

The ionization efficiency and fragmentation mechanism of methyl methacrylate (MMA) oligomers (3-mer∼8-mer) were investigated by using secondary ion mass spectrometry (SIMS) and APCI mass spectrometry (APCI-MS). Protonation and fragmentation mechanisms of MMA oligomers were clarified by using molecular orbital (MO) methods. MMA oligomers were synthesized in anionic polymerization, and the oligomers were fractionated into 3-mer∼8-mer using gel permeation chromatography (GPC). In SIMS of MMA oligomers (3-mer∼8-mer), [MH] +, [MH–CH 3OH] +, [MH–methyl formate] + and [MH–2CH 3OH–methyl formate] + appeared. The peak intensities of adduct ions [M+Li] +, [M+Na] + and [M+K] + increased with the increase of the polymerization degree. The optimized geometries and H +, Li +, Na + and K + affinities of MMA monomer (1-mer), dimer (2-mer), and trimer (3-mer) were calculated using the PM3 and ab initio MO methods. The calculated H +, Li +, Na + and K + affinities increased in order of 1-mer, 2-mer and 3-mer of MMA.

A highly substituted germacranolide from Leontodon cichoraceus.

A re-investigation of subaerial parts of Leontodon cichoraceus (Ten.) Sanguin. yielded the new germacrane-type sesquiterpenoid 15-beta-D-glucopyranosyl-8-[p-(beta-D-glucopyranosyloxy)phenylacetyl]-salonitenolide. The structure was established by APCI mass spectrometry and 1D- and 2D-NMR spectroscopy. A survey by HPLC-DAD and HPLC-MS gave no signs of this compound in 23 other taxa of Leontodon.

The Structurally Flexible Bicyclic Bis(2-hydroxyethanethiolato)bismuth(III) Complex: A Model for Asymmetric Monoanionic Chelation of Bismuth(III).

Reaction of Bi(NO(3))(3) with 2-mercaptoethanol gives [Bi(SCH(2)CH(2)OH)(2)][NO(3)], 5(NO(3)), independent of stoichiometry. Other salts or derivatives of 5, 5(Cl) and 5(Br), are readily prepared by anion exchange reactions and can also be obtained by reaction of BiX(3) (X = Cl, Br) with 2-mercaptoethanol. Reaction of Bi(CH(3)COO)(3) with 2-mercaptoethanol gives the conjugate base of 5 which is readily protonated with glacial acetic acid to give the acetate salt 5(CH(3)COO). The compounds have been characterized by IR, Raman, and NMR spectroscopies and APCI mass spectrometry. X-ray crystallographic studies of 5(NO(3)) [crystal data: C(4)H(10)O(5)BiS(2)N.H(2)O, I4(1)/a, a = 20.337(6) Å, b = 20.337(6) Å, c = 11.303(7) Å, Z = 16], 5(Cl) [crystal data: C(4)H(10)O(2)BiS(2)Cl, P2(1)/n, a = 8.653(2) Å, b = 10.618(3) Å, c = 10.564(2) Å, beta = 100.51(2) degrees, Z = 4], and 5(CH(3)COO) [crystal data: C(6)H(13)O(4)BiS(2), P2(1)/c, a = 8.089(2) Å, b = 16.313(3) Å, c = 8.708(2) Å, beta = 98.37(3) degrees, Z = 4] show them to each contain the bicyclic bis(2-hydroxyethanethiolato)bismuth framework 5. The conformational features of 5 are dramatically different in each of the structures, perhaps reflecting the relative donor capabilities of the anions. The observations reveal a substantial thermodynamic preference for the thiolate-alcohol chelate in a 2:1 stoichiometry over other possible structural arrangements, which is interpreted in terms of hard and soft acid-base theory and mediation of the acidity of the bismuth site by the double hydroxyl coordination.