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PubMed1997

Age and referral to coronary angiography after an abnormal treadmill thallium test.

This study investigated the association between age and referral to coronary angiography among ambulatory adults with an abnormal treadmill thallium scan. The subjects studied were 416 consecutive adults who were > or = 30 years old, under the care of cardiologists, and had an abnormal treadmill thallium scan between 1990 and 1993 at the Cleveland Clinic Foundation. The primary end point was performance of coronary angiography within 90 days of the treadmill test. Coronary angiography was performed in 163 subjects. Coronary angiography was performed in 46% of patients aged 30-49 years, in 53% of those aged 50 to 64 years, in 33% of those aged 65 to 74 years, and in only 18% of those aged > or = 75 years (chi2 test for trend, p < 0.0001). After adjustment for potential confounders, age remained associated with a lower rate of referral to angiography (p < 0.0001). During 2 years of follow-up 34 deaths occurred (14 cardiac), with particularly high mortality rates among those aged >74 years (cumulative rate 31%, 95% confidence interval 16% to 47%). The number of abnormal thallium scan segments was predictive of death (p = 0.02). These data suggest that increasing age is associated with a lower rate of referral to coronary angiography after an abnormal treadmill thallium test.

Adult↗
PubMed1999

Prediction of human transplantation arteriopathy and coronary events with lung/heart count ratios during intravenous dipyridamole thallium-201 imaging.

BACKGROUND: Cardiac allograft arteriopathy often limits long-term survival in transplantation recipients but has been difficult to detect by standard diagnostic methods. Because of the diffuse nature of transplantation coronary disease, we postulated that a lung/heart ratio during dipyridamole thallium imaging might better predict arteriopathy-related complications than diagnostic methods that detect discrete luminal stenoses. METHODS AND RESULTS: Sixty-six unselected heart transplantation recipients were evaluated with annual coronary arteriograms, endomyocardial biopsy, and intravenous dipyridamole thallium testing (initial study group). The mean lung/heart ratio on an anterior planar image was 0.40 for all patients; therefore <0.40 was arbitrarily defined as normal. After October 1992, 98 patients were tested (validation study group) and a lung/heart ratio cutoff of 0.40 was evaluated prospectively. Coronary end points were defined as (1) at least 1 coronary artery stenosis >/=50% of the luminal diameter, (2) sudden cardiac death, and (3) acute myocardial infarction. Stepwise logistic regression analysis was performed to identify independent predictors of future coronary end points. For the initial study group, the lung/heart ratio on the first annual thallium study was the only independent predictor of subsequent cardiac end points (0.47 +/- 0.13 [SD] with end points vs 0.38 +/- 0.11 without end points, P <.05). For the validation study group, independent predictors of subsequent coronary events included the lung/heart ratio and the radionuclide left ventricular ejection fraction. No patient with a lung/heart ratio <0.40 and a left ventricular ejection fraction >/=0.50 developed a cardiac event during 21 +/- 11 months of follow-up. CONCLUSIONS: A lung/heart ratio >/=0.40 on dipyridamole thallium testing is a sensitive predictor of coronary events after heart transplantation. Patients with heart transplantion who have a lung/heart ratio <0.40 and normal systolic left ventricular function are at low risk for subsequent coronary events and may not require annual surveillance by coronary arteriography.

Coronary Disease↗
PubMed1980

Nuclear cardiology. II. The role of myocardial perfusion imaging using thallium-201 in diagnosis of coronary heart disease.

Since its introduction, thallium-201 has become the agent of choice in the clinical assessment of relative myocardial perfusion. Extensive evaluation has shown that it is of particular value in the diagnosis of coronary heart disease in patients with baseline S-T segment abnormalities or an inadequate heart rate response resulting in an inconclusive exercise electrocardiographic response. In addition, thallium-201 imaging is of value in the patient with a suspected false positive stress test; however, the definite incidence of false negative studies in patients with coronary heart disease tempers complete reliance on this approach. In the patient with a diagnostic exercise electrocardiographic stress test, thallium-201 provides limited additional information. Moreover, current techniques of analysis do not permit assessment of the number of coronary arteries with obstructive lesions. In the setting of acute myocardial ischemia, the role of thallium-201 is less clear. In acute myocardial infarction, the significant incidence of false negative responses combined with a multiplicity of potential causes of resting defects including severe but chronic coronary disease or unstable angina limits its diagnostic value.

Acute Disease↗
PubMed1995

Microvascular angina pectoris in hypertensive patients with left ventricular hypertrophy and diagnostic value of exercise thallium-201 scintigraphy.

In a series of 120 hypertensive patients, 60 were found to have echocardiographic left ventricular (LV) hypertrophy (Devereux's method). Of these, 18 (30%) had typical stress-induced angina and underwent coronary angiography, which showed that 11 (61%) had normal coronary arteries, and 7 (39%) (p < 0.05) had coronary stenosis of the epicardial arteries. Stress-rest thallium-201 scintigraphy (Burow's quantitative method) yielded abnormal results in 21 of the 60 patients with LV hypertrophy. Five of 30 (17%) were asymptomatic, 14 of 18 (78%) had angina, and 2 of 12 (17%) had dyspnea on exertion. In 5 normal patients used as a control group, coronary flow reserve after administration of papaverine (10 coronary arteries) was 6.25 +/- 1.4 versus 3.7 +/- 0.8 in 10 thallium-negative, asymptomatic hypertensive patients with LV hypertrophy (p < 0.001). The mean coronary flow reserve of 21 patients with abnormal thallium-201 results was 2.71 +/- 0.96 (p < 0.01 compared with the group with normal thallium-201 findings) and 2.5 +/- 0.6 in the segments with lowest uptake (p < 0.05 compared with normal segments in these same patients). Thus, stress-induced angina pectoris in hypertensive patients with LV hypertrophy was due to small-vessel disease in over half of our patients (62%).

Adult↗
PubMed1982

Thallium myocardial imaging: recent experience using a coronary vasodilator.

Thallium-201 myocardial imaging is an important test in the assessment of patients with suspected coronary artery disease. Techniques differ in detail, reliability and in patient acceptability. Three techniques have been compared. Thirty-two-patients were studied in three groups. In the first group (15 patients) exercise thallium scans were compared with scans following an intravenous vasodilator (dipyridamole). In the second group (12 patients) intravenous dipyridamole and oral dipyridamole thallium scans were compared. In the third group (five patients) combined oral dipyridamole and exercise scans were assessed. There were no major differences in the first two groups but the combined test showed a marked increase in image quality and diagnostic yield. Thallium scanning is simplified considerably by the use of oral dipyridamole, without loss of diagnostic quality of safety. It promises to be the method of choice for stress scanning, and is ideal in patients unable to tolerate maximum exercise. The combined exercise--dipyridamole scan helps to evaluate complex problems, particularly those with less severe coronary insufficiency, and can be done without the use of a treadmill.

Administration, Oral↗
PubMed1986

Control of thallium and sodium fluxes in isolated adult rat heart cells by anthopleurin-A, verapamil and magnesium.

Anthopleurin-A stimulated the initial rate of 201thallium uptake by isolated adult rat heart cells by a factor of 3.41 +/- 0.56, and induced a unique pattern of spontaneous beating activity. Ouabain inhibited the basal uptake rate by 58 +/- 11% and all the anthopleurin-A stimulated rate. The Km for thallium uptake was 0.95 +/- 0.26 mM, and was not changed by anthopleurin-A. Accumulated thallium was quickly released from cells by EDTA addition. Such release was inhibited 87 +/- 10% by verapamil. Thallium reuptake was initiated by restoration of magnesium to the medium. Reuptake was mostly inhibited by ouabain, but the residual ouabain-insensitive uptake remained. The ouabain-insensitive uptake was inhibited by ATP depletion. Anthopleurin-A stimulated the rate of 22Na entry into cells by a factor of 3.17 +/- 1.65, and EDTA stimulated the rate of entry by a factor of 29.5 +/- 13.0. The EDTA-induced 22Na entry was inhibited 86 +/- 11% by verapamil. From this we draw three conclusions: The major pathway for thallium uptake is the Na-K pump. The rate of uptake by this route, like the rate of K+ uptake, is governed by the rate of cellular sodium influx; A residual ouabain-insensitive uptake route also exists which appears to require ATP but not a monovalent ion gradient; Removal of Mg and Ca induces a verapamil-sensitive monovalent channel activity which is both massive and reversible.

Animals↗
PubMed1998

Prediction of restenosis after successful percutaneous coronary angioplasty by dobutamine thallium-201 scintigraphy.

We evaluated the accuracy of dobutamine thallium-201 myocardial perfusion scintigraphy in predicting restenosis after successful percutaneous coronary angioplasty. Restenosis is one of the most important problems in patients who have undergone percutaneous coronary angioplasty. Exercise thallium-201 myocardial perfusion scintigraphy has been a well accepted non-invasive method to predict the restenosis of the dilated vessel after percutaneous coronary angioplasty, however, the role of thallium-201 myocardial perfusion using dobutamine, as a substitute for exercise in patients unable to exercise, in predicting restenosis is not well known. Therefore, 34 consecutive patients underwent dobutamine tomographic (single photon emission computed tomography) thallium-201 myocardial perfusion scintigraphy following a total of 37 successful angioplasties. No serious side effects during dobutamine infusion occured. The interval between percutaneous coronary angioplasty and scintigraphy ranged between 8 weeks to 2 years. All patients underwent control angiography within one month following myocardial perfusion scintigraphy. Sensitivity, specificity and accuracy of dobutamine myocardial imaging for predicting restenosis were 76%, 79% and 77%, respectively. Sensitivity and specificity related to the vascular territories were: left anterior descending artery 66-69%, left circumflex artery 75-100%, right coronary artery 83-66%, respectively. In conclusion, our findings demonstrating high accuracy of dobutamine myocardial single photon emission tomography for angiographic restenosis suggest its usefulness as a non-invasive tool in the follow-up of percutaneous coronary angioplasty patients.

Aged↗
PubMed2001

Assessment of the myocardial changes in heart transplant recipients without evident acute myocardial rejection by integrated backscatter: comparison with simultaneous dobutamine stress echocardiography and (201)thallium spect.

Cardiomyocyte hypertrophy and interstitial fibrin deposition develop in cardiac allografts and contribute to the functional changes of transplanted hearts. We hypothesized that integrated backscatter (IBS) can detect these myocardial changes. A total of 32 heart transplant recipients with either no or mild acute rejection (International Society of Heart and Lung Transplantation grade IA) were enrolled in this study. IBS data of myocardium were collected immediately before simultaneous dobutamine stress echocardiography (DSE) and (201)thallium imaging. Coronary angiography and endomyocardial biopsy were also performed. Coronary angiography showed diffuse narrowing in 1 patient who also had abnormal results of IBS, DSE, and thallium results. In the other 31 patients with patent coronary arteries, there were 3 patients (10%) with abnormal DSE results, 19 patients (61%) with abnormal IBS patterns, and 16 patients (52%) with reversible thallium perfusion defects. Of the patients, 44% had cardiomyocyte hypertrophy and 56% interstitial fibrin deposition. There were significant differences in the prevalence of (201)thallium perfusion defects and serum cyclosporine levels between patients with and without abnormal IBS patterns. Pathologic changes were also associated with abnormal IBS patterns (p = 0.01). However, there was no association between abnormal IBS and DSE results. By multiple logistic regression analysis, the abnormal IBS patterns were associated inversely with serum cyclosporine level (p = 0.028). In conclusion, abnormal IBS patterns are associated significantly with perfusion heterogeneity and pathologic changes in heart transplant recipients without evident acute myocardial rejection. There is no association between abnormal IBS patterns and dobutamine-induced dyssynergy in these patients. IBS provides a noninvasive approach for detection of myocardial changes in transplanted hearts without evident acute rejection.

Cardiac Catheterization↗
PubMed2001

Variability of myocardial perfusion defects assessed by thallium-201 scintigraphy in patients with coronary artery disease not amenable to angioplasty or bypass surgery.

OBJECTIVES: We sought to assess the variability of results obtained with thallium scintigraphy as a method for tracking the extent of myocardial ischemia in medically refractory patients with angina who are not suitable for coronary artery bypass graft surgery or percutaneous transluminal coronary angioplasty. BACKGROUND: New therapies are being evaluated for patients with "no option" angina in whom medical therapy has failed. Nuclear techniques, like thallium scintigraphy, are used in multicenter trials to evaluate whether such therapies improve myocardial perfusion. However, the variability of test results is unknown in this patient group in a multicenter study. METHODS: The Angina Treatments: Lasers And Normal Therapies In Comparison (ATLANTIC) study was a randomized trial of transmyocardial laser revascularization (n = 182). Patients underwent dipyridamole thallium stress tests at baseline and 3, 6 and 12 months after enrollment. The control group (n = 90) was treated with constant medical therapy during the study and is a relevant group to investigate test variability. Test variability over time was quantified by the mean absolute change in the percentage of reversible perfusion defects between baseline and follow-up. RESULTS: Baseline percent myocardium with ischemia averaged 17.0 +/- 13.7% and did not change during follow-up. However, variations in the percent myocardium with reversible perfusion defects over time amounted to an average of 6 to 8 percentage points, or 43% to 55% of the baseline value. Only approximately 13% of this variability was attributable to variability in image reconstruction and analysis. CONCLUSIONS: As demonstrated in the ATLANTIC study, percent myocardial ischemia in control subjects receiving constant medical therapy varied in individual patients by an average of approximately 50%. This may limit the utility of thallium scintigraphy to detect improved myocardial perfusion over time in response to therapy.

Coronary Disease↗
PubMed1984

Noninvasive diagnostic test choices for the evaluation of coronary artery disease in women: a multivariate comparison of cardiac fluoroscopy, exercise electrocardiography and exercise thallium myocardial perfusion scintigraphy.

Several diagnostic noninvasive tests to detect coronary and multivessel coronary disease are available for women. However, all are imperfect and it is not yet clear whether one particular test provides substantially more information than others. The aim of this study was to evaluate clinical findings, exercise electrocardiography, exercise thallium myocardial scintigraphy and cardiac fluoroscopy in 92 symptomatic women without previous infarction and determine which tests were most useful in determining the presence of coronary disease and its severity. Univariate analysis revealed two clinical, eight exercise electrocardiographic, seven myocardial scintigraphic and seven fluoroscopic variables predictive of coronary or multivessel disease with 70% or greater stenosis. The multivariate discriminant function analysis selected a reversible thallium defect, coronary calcification and character of chest pain syndrome (p less than 0.05) as the variables most predictive of presence or absence of coronary disease. The ranked order of variables most predictive of multivessel disease were cardiac fluoroscopy score, thallium score and extent of ST segment depression in 14 electrocardiographic leads. Each provided statistically significant information to the model. The estimate of predictive accuracy was 89% for coronary disease and 97% for multivessel coronary disease. The results suggest that cardiac fluoroscopy or thallium scintigraphy provide significantly more diagnostic information than exercise electrocardiography in women over a wide range of clinical patient subsets.

Adult↗
PubMed1986

Thallium-201 myocardial imaging during pharmacologic coronary vasodilation: comparison of oral and intravenous administration of dipyridamole.

Although the diagnostic utility of thallium-201 myocardial imaging after dipyridamole infusion is well established, the intravenous form of the drug is not yet commercially available in North America. Fifty patients referred for coronary angiography were prospectively studied. Within a 2 week period, each patient underwent cardiac catheterization and thallium-201 myocardial imaging after both oral and intravenous dipyridamole administration. For the oral protocol, patients were randomly assigned to treatment with either 200 or 400 mg of dipyridamole in tablet form. Coronary artery stenoses of 70% or greater were considered significant. For the 25 patients who received a 200 mg oral dose of dipyridamole, the scintigraphic study showed perfusion defects in 65% of patients with significant coronary artery disease after the oral dose and in 85% of patients after the intravenous dose. For the 25 patients who received a 400 mg oral dose, the sensitivity of the scintigram was 84% after the oral dose and 79% after the intravenous dose. Except for headache and nausea, side effects were less severe and less frequent with oral (either 200 or 400 mg) than with intravenous dipyridamole. Because of the delayed and variable absorption of dipyridamole tablets, the oral studies required a longer period of medical supervision (45 to 60 minutes), and aminophylline was empirically administered after completion of the first set of thallium-201 images. It is concluded from this study that thallium-201 myocardial imaging after coronary vasodilation with a 400 mg oral dose of dipyridamole is a safe, widely available and reliable alternative for the evaluation of coronary artery disease in patients unable to achieve an adequate exercise level on stress testing.

Administration, Oral↗
PubMed1987

Arm exercise-thallium imaging testing for the detection of coronary artery disease.

Patients with lower limb impairment are often unable to undergo a standard bicycle or treadmill test for the evaluation of coronary artery disease. To establish an alternative method of testing, 50 subjects (aged 56 +/- 10 years) performed arm ergometry testing in conjunction with myocardial thallium scintigraphy. All underwent coronary angiography; significant coronary artery disease (greater than or equal to 70% stenosis) in at least one vessel was present in 41 (82%) of the 50 patients. Thallium scintigraphy was found to have an 83% sensitivity and 78% specificity for detecting coronary disease, compared with a sensitivity and specificity of 54% (p less than 0.01) and 67% (p = NS), respectively, for exercise electrocardiography. In the subgroup of 23 patients who had no prior myocardial infarction or left bundle branch block and were not taking digitalis, thallium scintigraphy had a sensitivity of 80% versus 50% for exercise electrocardiography. Scintigraphy yielded a sensitivity of 84, 74 and 90% for one, two and three vessel disease, respectively. Noninvasive arm ergometry exercise-thallium imaging testing appears to be reliable and useful and should be considered in the evaluation of coronary artery disease in patients with lower limb impairment.

Adult↗
PubMed1999

Comparison of pulmonary uptake with transient cavity dilation after exercise thallium-201 perfusion imaging.

OBJECTIVES: The purpose of the study was to evaluate the relationship between elevated lung/heart ratio (LHR) and transient ischemic dilation (TID) after stress thallium-201 myocardial perfusion imaging and to provide further insight into the mechanism of cavity dilation. BACKGROUND: Because both LHR and TID have been identified as adjunctive markers of severe coronary disease they should be found in the same patients. Although the mechanism of LHR has been defined, that of transient dilation has not. METHODS: We identified 4,618 consecutive patients undergoing maximal exercise perfusion imaging with thallium-201. Lung/heart ratio and a dilation index were derived and compared to each other and to relevant clinical parameters. RESULTS: There was a very weak relationship between the LHR and dilation index (r = 0.15, p < 0.001). Defining a dilation index > or =1.10 and LHR > or =50% as abnormal revealed that 322 of the patients (7%) had TID only, 351 (7.8%) had LHR only and 40 (0.9%) had both. When compared to patients without these findings both TID and LHR had higher thallium stress defect and redistribution scores. When comparing subjects who had elevated LHR uptake to those who had TID, it was found that those with LHR were more likely to have had prior myocardial infarction (MI) (29% vs. 9%), coronary artery bypass grafting (22% vs. 8%), lower ejection fraction (34+/-17% vs. 55+/-11%) and had more evidence of ischemia based on thallium stress defect and redistribution scores. However, patients with cavity dilation had a higher frequency of positive electrocardiographic response (31% vs. 19%) despite lower scintigraphic markers. CONCLUSIONS: Although pulmonary uptake and transient cavity dilation have both been associated with severe coronary disease, they have a very weak correlation, which, in combination with the different clinical parameters associated with each, suggests that they represent different pathophysiologic responses to exercise-induced ischemia. Our data support the hypothesis that TID represents transient subendocardial ischemia rather than physical dilation from increased end-diastolic pressure.

Coronary Disease↗
PubMed1999

Silver and thallium(I) complexation with dibenzo-16-crown-4.

Dibenzo-16-crown-4 (1) indicates high silver and thallium(I) ion selectivity over sodium, potassium, and rubidium ion evaluated from the solvent extraction of metal picrates, while its cation-binding ability is lower than those of dibenzo-18-crown-6 (2) and dibenzo-22-crown-6 (3). Taking account of the highest thallium(I) ion selectivity for 1 obtained from extraction experiments, PVC membrane thallium(I)-selective electrodes based on 1 are prepared. The electrode shows the best potentiometric selectivity coefficients for thallium(I) over potassium and rubidium than those of 2 and 3, and commercially available bis(crown ether)s (4).

Crown Ethers↗
PubMedDate not supplied

Impact on exercise single-photon emission computed tomographic thallium imaging on patient management and outcome.

BACKGROUND: Stress perfusion imaging is useful in risk stratification of patients with known or suspected coronary artery disease. In the current era of managed health care, there is a need to provide data on patient outcome. METHODS AND RESULTS: This study examined the impact of exercise single-photon emission computed tomographic (SPECT) thallium imaging on patient management (the subsequent need for coronary angiography and revascularization) and outcome (the occurrence of hard cardiac events defined as cardiac death or nonfatal acute myocardial infarction) in 2700 patients who were being evaluated for diagnostic purposes. None of the patients had previous coronary angiography, coronary revascularization, or Q-wave myocardial infarction. The SPECT images were normal in 2027 patients (group 1) and abnormal in 673 patients (group 2). Within 6 months after thallium imaging 53 patients in group 1 (3%) and 242 patients in group 2 (36%) underwent coronary angiography (p = 0.0001). The patients who underwent coronary angiography had higher pretest probability of coronary disease (group 1) or more perfusion defects (group 2) than patients who did not (p = 0.0001 each). Coronary revascularization within 3 months of coronary angiography was performed in 1 of the 53 patients (2%) in group 1 and in 87 of 242 patients (30%) in group 2 (p = 0.0001). Among the remaining patients who had coronary angiography but were medically treated there were no hard cardiac events in group 1 but there were 15 events in group 2 (p = 0.02). CONCLUSIONS: The results of exercise SPECT thallium imaging are important in patient management and outcome. Coronary angiography, coronary revascularization and events are rare in patients with normal exercise SPECT thallium images.

Adult↗
PubMed2003

Thallium in soils and stream sediments of a Zn-Pb mining and smelting area.

Thallium was determined in 120 samples of soil and 30 samples of stream sediments from the southeastern part of the Silesian-Cracowian zinc-lead ore deposits. Soil samples were taken from topsoils (0.0-0.2 m) and bottom soils (0.8 and 1.0 m). Thallium was determined by flow-injection-differential-pulse anodic stripping voltammetry. The samples were decomposed sequentially with 73% hydrofluoric acid and a mixture of nitric acid and hydrogen peroxide. The results showed that zinc-lead ore mining as well as their processing and smelting leads to a significant increase of thallium in the top layer of soil and in stream sediments. The highest recorded concentration was 150 ppm Tl for stream sediment and 35 ppm for a soil sample. Thallium concentration in small rivers from the investigated area was by 2 orders of magnitude higher than in the reference area. The highest recorded concentration being 3.24 microg L(-1).

Environmental Monitoring↗
PubMed2001

Structure of the dimethyl sulfoxide solvated thallium(III) ion in solution and in the solid state.

The structure and vibrational spectra of the dimethyl sulfoxide solvated thallium(III) ion have been studied in a dimethyl sulfoxide solution and in the solid state. X-ray crystallography shows a trigonal unit cell, space group R(-)3 (No. 148), for the [Tl(dmso)(6)](ClO(4))(3) compound with Z = 3, a = b = 11.9764(13) [11.8995(9)] A, c = 20.802(2) [20.467(2)] A, and V = 2584.0(5) [2509.9(4)] A(3) at 295 [150] K. The crystal structure comprises a highly symmetric hexakis(dimethyl sulfoxide)thallium(III) ion, with thallium in a (-)3 symmetry site and a Tl-O bond distance of 2.224(3) A at 295 K. The octahedral TlO(6) kernel is compressed along the threefold axis with an O-Tl-O bond angle of 96.20(11) degrees. The Tl-O-S bond angle of 120.7(2) degrees corresponds to a Tl.S distance of 3.292(2) A. One perchlorate ion centered on the (-)3 axis was described by a statistically disordered model. A low-temperature EXAFS study (10 K) resulted in the Tl-O and Tl.S distances of 2.221(4) and 3.282(6) A, respectively, consistent with a Tl-O-S bond angle of 120(1) degrees. The low Debye-Waller factors confirm a regular coordination without the disorder of the dimethyl sulfoxide ligands, which would have resulted from the alternative choice of space group R3 for the crystal structure. Raman and infrared spectra have been recorded and assigned, with the bands at 435 and 447 cm(-)(1) corresponding to the vibrational frequency of the symmetric and asymmetric Tl-O stretching modes, respectively. EXAFS data of a 0.5 mol dm(-3)thallium(III) trifluoromethanesulfonate in a dimethyl sulfoxide solution were consistent with that of a hexasolvated ion with mean Tl-O and Tl.S distances of 2.22(1) and 3.33(2) A, respectively, which correspond to a mean Tl-O-S bond angle of 124(2) degrees. The anomalously large disorder parameter for the Tl-O distances is consistent with a weak pseudo-Jahn-Teller effect. The (205)Tl, (13)C, and (1)H NMR spectra of the complex in solution show single signals at 1886, 39.5, and 2.3 ppm, respectively.

Cations↗
PubMed2002

Structure of the solvated thallium(I) ion in aqueous, dimethyl sulfoxide, N,N'-dimethylpropyleneurea, and N,N-dimethylthioformamide solution.

The structure of the solvated thallium(I) ion in aqueous, dimethyl sulfoxide, N,N'-dimethylpropyleneurea, and N,N-dimethylthioformamide solution has been studied by means of large-angle X-ray scattering (LAXS) and complemented by EXAFS studies on two systems. The first solvation shell around the thallium(I) ion comprises significantly different bond distances to the solvent molecules in solution, indicating a stereochemically active lone electron pair. The first hydration shell around the thallium(I) ion in aqueous solution can be modeled by two Tl-O bond distances at 2.73(2) A and about two more at 3.18(6) A. Thallium(I) ions solvated by dimethyl sulfoxide, N,N'-dimethylpropyleneurea, and N,N-dimethylthioformamide seem to have two short and four long Tl-solvent bond distances. The mean Tl-O bond distances of the two groups were 2.66(4) and 3.18(6) A for dimethyl sulfoxide and 2.73(4) and 3.27(8) A for N,N'-dimethylpropyleneurea. For the sulfur donor solvent N,N-dimethylthioformamide the corresponding groups of Tl-S bond distances were refined to 2.96(2) and 3.33(3) A.

Cations↗