bluuebunny/crossref_metadata_2025 huggingface dataset:
Congenitally corrected transposition of the great arteries: clues for prenatal diagnosis
Authors: McEwing R. L. , Chaoui R.
Published: February 2004

Congenitally corrected transposition of the great arteries (ccTGA) is an uncommon cardiac defect characterized by the atria connecting with the anatomically discordant ventricles and the ventricles connecting with discordant and transposed great arteries. Parallel vessels are evident in corrected TGA, but as this sign is also present in complete TGA, a heart anomaly requiring major cardiac surgery in the postnatal period, it is important to differentiate between the entities prenatally. Most cases of ccTGA have associated anomalies but isolated forms or those with a mild associated cardiac anomaly are infrequently detected prenatally. We report on three cases detected between 21 and 25 weeks' gestation on screening ultrasound with associated mild findings. One fetus had an isolated ventricular septal defect (VSD) first detected at 34 weeks. The child developed heart block at 4 years of age. The second case was associated with a small VSD, a tiny pulmonary trunk and a persistent right umbilical vein. After birth, mild pulmonary stenosis was found as an additional cardiac finding at 4 months of age. The third fetus had no additional cardiac anomalies prenatally, but after birth a bicuspid aortic valve was detected. The first case needed pacemaker implantation but the other two children required no cardiac surgery. Two of the cases were referred because abnormal vessel anatomy was detected on screening ultrasound. As prenatal detection of TGA is becoming a more frequent occurrence, this paper aims to present clues aiding in the prenatal diagnosis of atrioventricular and ventriculoarterial discordance, especially in its differentiation from complete transposition. These details are crucial for counseling and perinatal management. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
What women want: women's preferences of caregiver behavior when prenatal sonography findings are abnormal
Authors: Alkazaleh F. , Thomas M. , Grebenyuk J. , Glaude L. , Savage D. , Johannesen J. , Caetano M. , Windrim R.
Published: February 2004

Objective

To determine what women value when receiving news of a pregnancy abnormality detected by ultrasound.

Methods

Women who had a pregnancy complication detected sonographically in the year 2000 were asked to complete a survey of 21 questions measuring the importance of various factors related to the receipt of bad news. Of the target sample of 117 women who agreed to participate, 76 (64.9%) returned completed surveys. Cases included serious anomalies (67%) and soft markers/obstetric complications (33%).

Results

Responses to questions on ‘information quality’, ‘prompt provision of information’, ‘information‐provider behavior’ and ‘information provision environment’ showed that women attached the most importance to information quality, much more so than to promptness. Speed was even less important than information‐provider empathy. Answers concerning use of the terms ‘fetus’ or ‘baby’ revealed greater variation in preferences than any other. Privacy was the most important environmental variable, more important than some information quality variables, or any promptness variable. Intervening variables considered included demographic variables and the seriousness of the prognosis. Education was the most useful predictor of preferences, with highly educated women generally placing less value on environment and some information quality variables, and having different preferences concerning the terms ‘fetus’ and ‘baby’.

Conclusions

Our findings shed some light on what is important to women who face bad news. Although more research is needed in this important area, we hope that our findings may assist institutions and caregivers in establishing guidelines for the effective and considerate communication of bad news. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Effect of parity on second‐trimester uterine artery Doppler flow velocity and waveforms
Authors: Prefumo F. , Bhide A. , Sairam S. , Penna L. , Hollis B. , Thilaganathan B.
Published: February 2004

Objectives

To investigate the relationship between second‐trimester uterine artery Doppler findings and parity in a large pregnant population.

Methods

Uterine artery Doppler studies were performed in all singleton pregnancies at 18–23 weeks of gestation. The mean uterine artery resistance index and the presence or absence of protodiastolic notches were recorded. Two groups were identified: pregnancies not complicated by pre‐eclampsia, and pregnancies with pre‐eclampsia severe enough to require delivery at or before 32 weeks of gestation.

Results

In the 4132 pregnancies uncomplicated by pre‐eclampsia, parity was shown to be an independent predictor for both mean uterine artery resistance index (beta = 0.073, P < 0.001) and the presence of bilateral protodiastolic notches (odds ratio = 0.67; 95% CI, 0.45–0.98). In the 17 pregnancies complicated with severe pre‐eclampsia, uterine artery Doppler indices showed a trend towards being better predictors of disease in nulliparous compared with parous women.

Conclusion

Parity has a significant effect on the resistance index and the prevalence of protodiastolic notching in the uterine artery flow waveforms. This difference is clinically noticeable in its effect on notching. These findings suggest that some permanent modification may persist in the maternal vessels after a successful pregnancy, altering their impedance in subsequent pregnancies. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
The value of uterine artery Doppler in the prediction of uteroplacental complications in multiparous women
Authors: Harrington K. , Fayyad A. , Thakur V. , Aquilina J.
Published: February 2004

Objective

To investigate the value of second‐trimester uterine artery Doppler in the prediction of complications resulting from uteroplacental insufficiency in low‐ and high‐risk multiparous women.

Methods

Color flow pulsed Doppler imaging of both uterine arteries at 20 weeks' gestation was performed on 628 multiparous women; 458 of them had no known risk factors and 170 had clinically identifiable high‐risk factors at booking. An abnormal result was defined as bilateral notches and a mean resistance index (RI) ≥ 0.55 (50th centile) or unilateral notches and a mean RI ≥ 0.65 (80th centile). The main outcome measure was adverse pregnancy outcome defined as any case of pre‐eclampsia, small‐for‐gestational age birth weight (< 5th centile), placental abruption, stillbirth or early neonatal death.

Results

There was an adverse outcome in 30 women (6.6%) in the low‐risk group and 48 (28.2%) women in the high‐risk group. In the high‐risk group the sensitivity to predict adverse pregnancy outcome in screen‐positive women was 81.4% for a specificity of 89.0%, a positive predictive value of 71.4% and a negative predictive value of 93.4%. Normal Doppler studies in the high‐risk group conferred a risk of adverse perinatal outcome of 6.6%, similar to the risk of adverse outcome in the low‐risk population (6.6%). In the low‐risk group the sensitivity for an adverse outcome in screen‐positive women was 33.3% for a specificity of 92.8% and a positive predictive value of 24.4%.

Conclusion

In high‐risk multiparous women, persistent bilateral notches with mean RI ≥ 0.55 and unilateral notches with mean RI ≥ 0.65 at 20 weeks' gestation identifies the vast majority of women who will subsequently develop complications secondary to uteroplacental insufficiency. Normal uterine artery Doppler studies in these women confers a risk of adverse outcome similar to that of women with an uncomplicated obstetric history. In low‐risk women, the screening efficacy of uterine artery Doppler for adverse perinatal outcome is poor and does not justify routine screening. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Determining zygosity in early pregnancy by ultrasound
Authors: Tong S. , Vollenhoven B. , Meagher S.
Published: February 2004

Objectives

First‐trimester ultrasound can reliably determine chorionicity but not zygosity. We set out to investigate whether it may be possible to determine zygosity using ultrasound by noting the number of corpora lutea (CLs), structures which reflect ovulation. In the presence of a dichorionic twin pregnancy, the identification of one CL would suggest that twins are monozygotic whereas two CLs implies dizygosity.

Methods

This was a retrospective analysis of predominantly spontaneous twin pregnancies presenting for an early pregnancy ultrasound at 5–8‐completed weeks of gestation. Placentation was correlated with presumed zygosity as predicted by the number of CLs present.

Results

Of 33 twin gestations, chorionicity was compatible in all cases with the predicted zygosity. In 15 cases one CL was seen and these were designated monozygotic. Of these, four were of monochorionic placentation and 11 dichorionic. The remaining 18 cases had two CLs and were presumed dizygotic; all were of dichorionic placentation.

Conclusion

We propose a novel technique of zygosity determination during very early pregnancy which may have implications both clinically and in genetic research involving twins. However, this study requires further verification by comparing ultrasound results with DNA evidence taken after birth. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Ultrasound imaging of the pelvic floor. Part I: two‐dimensional aspects
Authors: Dietz H. P.
Published: February 2004

Ultrasound imaging is rapidly replacing radiological methods in the investigation of pelvic floor disorders. Transrectal, transvaginal/introital and transperineal/translabial methods are being employed, with the latter probably the most widespread due to ease of use and availability of equipment. Position and mobility of the bladder neck, bladder wall thickness, pelvic floor muscle activity and uterovaginal prolapse can be quantified, and color Doppler may be used to document stress urinary incontinence. Ultrasound imaging has simplified audit activities and enhanced our understanding of the effects of incontinence and prolapse surgery, such as the new synthetic suburethral slings. In recent years, imaging methods have contributed significantly to our understanding of the traumatic effects of childbirth on the pelvic floor. Finally, the assessment of pelvic floor biomechanics may have implications for clinical obstetrics and ultimately for the prevention of delivery‐related pelvic floor trauma. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Width of the fetal lateral ventricular atrium between 10 and 12 mm: a simple variation of the norm?
Authors: Signorelli M. , Tiberti A. , Valseriati D. , Molin E. , Cerri V. , Groli C. , Bianchi U. A.
Published: February 2004

Objectives

The prognosis of borderline forms of anomalies that can be detected by ultrasound is one of the most challenging issues in prenatal diagnosis. The aim of this study was to determine the prognosis for fetuses presenting with isolated mild ventriculomegaly (MVM).

Methods

Fetuses in which the width of the lateral ventricular atria was 10–12 mm and which had no other detectable chromosomal or morphological anomalies were followed by monthly ultrasound examinations until delivery. For the cases identified up to December 1997, postnatal information was gathered retrospectively through interviews. Children born from January 1998 onwards were included in a protocol involving planned neuropsychiatric visits at 12 and 18 months of age in which the Griffith scale was used to assess neurodevelopment.

Results

Between September 1992 and January 2001, 60 fetuses with isolated MVM were identified. Ventricular dilatation diminished in 18 cases (and became normal in nine of these) and stabilized in 42 cases. Information was obtained on 38 children born up to December 1997 and their neurodevelopment was found to be completely normal. The 22 children born from January 1998 onwards showed normal development at 12 and 18 months of age.

Conclusions

When MVM is observed on prenatal ultrasound examination it can be very difficult to offer parents appropriate counseling. It is important to exclude aneuploidy or morphological abnormalities but even then there will be anxieties about long‐term neurological outcome. Our data, which show normal neurodevelopment between 18 months and 10 years after birth in cases of MVM (10–12 mm), should provide a basis for reassuring counseling. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Sex‐specific fetal weight prediction by ultrasound
Authors: Schild R. L. , Sachs C. , Fimmers R. , Gembruch U. , Hansmann M.
Published: February 2004

Objective

To improve sonographic birth‐weight prediction by developing fetal gender‐specific formulae.

Methods

This was a retrospective cross‐sectional study. Two gender‐specific formulae were produced from the data of 527 patients and the data of a further 349 patients were used to evaluate the formulae. Inclusion criteria were a singleton live fetus, gestational age above 25 weeks, birth weight between 1000 g and 4500 g and fetal biometry within 8 days of delivery. Data retrieval was specifically for the purpose of this study.

Results

To yield the best‐fit weight formula for each fetal gender we employed step‐wise regression analysis based on fractional polynomials with the biometric parameters biparietal diameter (BPD), head circumference (HC), transverse abdominal diameter (TAD), abdominal circumference (AC) and femur length (FL): estimated fetal weight for girls (g) = − 4035.275 + 1.143 × BPD3 + 1159.878 × AC1/2 + 10.079 × FL3 − 81.277 × FL2 [in cm]; estimated fetal weight for boys (g) = 43576.579 + 1913.853 × log10BPD + 0.01323 × HC3 + 55.532 × AC2 − 13602.664 × AC1/2 − 0.721 × AC3 + 2.31 × FL3 [in cm]. These formulae showed superior results compared with those of conventional weight formulae.

Conclusion

Gender‐related fetal weight calculation allows optimized prediction of fetal weight at birth. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Caroli's disease: prenatal diagnosis, postnatal outcome and genetic analysis
Authors: Sgro M. , Rossetti S. , Barozzino T. , Toi A. , Langer J. , Harris P. C. , Harvey E. , Chitayat D.
Published: February 2004

Caroli's disease is a rare autosomal recessive condition characterized by cystic dilatation of the intrahepatic bile ducts and infantile polycystic kidney disease. We report a case with Caroli's disease detected prenatally at 33 weeks' gestation with fetal ultrasound findings of a cystic liver mass and echogenic kidneys. Postnatal investigation confirmed enlarged and echogenic kidneys with dilatation of the intrahepatic bile ducts consistent with the diagnosis of Caroli's disease. Genetic analysis of the gene, PKHD1, associated with autosomal recessive polycystic kidney disease (ARPKD) showed that the patient had compound heterozygous mutations, confirming that this early onset Caroli's disease was part of the spectrum of ARPKD. To our knowledge this is the third case of Caroli's disease detected prenatally and the first in which the infant survived. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Contrast‐enhanced sonography during uterine artery embolization for the treatment of leiomyomas
Authors: Marret H. , Tranquart F. , Sauget S. , Alonso A. M. , Cottier J.‐P. , Herbreteau D.
Published: February 2004

Uterine artery embolization (UAE) is a successful and safe treatment for symptomatic leiomyomas. However, rare complications such as premature menopause and uterine necrosis can arise because of embolization of non‐target tissues. We studied the feasibility of using contrast‐enhanced sonography with intravenous SonoVue just before, during and after complete occlusion of both uterine arteries. In a patient with multiple, large, symptomatic leiomyomas, contrast‐enhanced imaging established that the UAE was technically successful and that myometrial vascularity was not reduced. Our case suggests that ultrasound contrast agents may have a role in monitoring UAE and thus may help prevent ischemic complications. Further studies are required to confirm this. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
The cocoon sign: a potential sonographic pitfall in the diagnosis of twin – twin transfusion syndrome
Authors: Quintero R. A. , Chmait R. H.
Published: February 2004

Objectives

To investigate the frequency and clinical importance of the cocoon sign in twin–twin transfusion syndrome (TTTS).

Methods

Charts and ultrasound images of all pregnancies with TTTS that underwent selective laser photocoagulation of communicating vessels at our institution over a 1‐year period were retrospectively reviewed for a cocoon sign. TTTS had been diagnosed and prospectively staged if monochorionicity was suspected and the maximum vertical pocket (MVP) of amniotic fluid in one gestational sac was ≥8 cm, while the MVP in the other gestational sac was ≤2 cm. The cocoon sign was diagnosed when there was an ultrasound finding of a donor twin with severe oligohydramnios enveloped by dividing membranes and connected to the uterine wall by a laminar stalk of these membranes.

Results

The cocoon sign was noted in 9/58 (15.5%) cases. There were no differences in gestational age and stage of TTTS upon presentation, gestational age at delivery or number of neonatal survivors between the groups of TTTS cases with and those without a cocoon sign. One patient in the cocoon group had been misdiagnosed because the donor twin's MVP was measured from the donor's tethered membranes to the posterior wall of the uterus within the recipient's sac.

Conclusions

The cocoon sign is present in at least 15% of patients with TTTS. Its recognition is important to avoid misdiagnosis of TTTS. The practical implications and potential complications of this sonographic sign are discussed. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
The value of detection of normal ovarian tissue (the ‘ovarian crescent sign’) in the differential diagnosis of adnexal masses
Authors: Hillaby K. , Aslam N. , Salim R. , Lawrence A. , Raju K. S. , Jurkovic D.
Published: February 2004

Objective

The aim of the study was to evaluate whether the presence of normal ovarian tissue adjacent to an adnexal tumor (the ‘ovarian crescent sign’) could assist in the preoperative differential diagnosis of adnexal lesions.

Methods

This was a prospective observational study including 100 women with a preoperative diagnosis of an adnexal mass. Demographic and biochemical data were collected and all women underwent a detailed transvaginal ultrasound scan. Tumor volume, morphological characteristics and Doppler features were recorded in each case. In addition, the tissue adjacent to the cyst was systematically examined for the presence of normal ovarian tissue. All the findings were compared to the final histological diagnosis.

Results

Sixty‐seven (67%) of the cysts removed were benign, nine (9%) were borderline and 24 (24%) women had invasive malignant lesions. Normal ovarian tissue was seen in 58/76 (76%) women with non‐invasive lesions, and in one woman (4%) with an invasive malignancy. In the absence of normal ovarian tissue, ovarian cancer was diagnosed with a sensitivity of 96% and specificity of 76%.

Conclusion

The presence of normal ovarian tissue adjacent to an ovarian cyst is a useful morphological feature that may be used to help exclude an invasive ovarian malignancy in women with adnexal masses detected on ultrasound scan. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Fetal heart rate and blood flow velocity variability in the presence of increased nuchal translucency: a preliminary study
Authors: Vinkesteijn A. S. M. , Ursem N. T. C. , Struijk P. C. , Wladimiroff J. W.
Published: February 2004

Objective

To study the power spectrum distribution of heart rate and umbilical artery flow velocity variability in fetuses with increased nuchal translucency thickness (NT).

Methods

Doppler velocity waveforms were collected from long‐lasting (>20 s) umbilical artery recordings in 18 fetuses with increased NT (>3 mm) and 18 normal controls matched for gestational age at 11–14 (median, 12) weeks. The NT group included 11 abnormal karyotypes: trisomy 18 (n = 3), 45,X (n = 4), trisomy 21 (n = 3) and a balanced translocation. Absolute heart rate as well as the coefficient of variation for both beat‐to‐beat heart rate variability and umbilical artery blood flow velocity variability were determined. The ratios of the integrated low‐frequency components (0.05–0.2 Hz) and the integrated high‐frequency ones (0.25–1.6 Hz; LH ratio) from normalized power spectrum distributions were established to reflect sympathovagal balance.

Results

The mean heart rate was not significantly different between the two groups. However, mean heart rate variability and time‐averaged flow velocity variability were significantly increased in the NT group, while there was no significant difference in the LH ratios between the two groups. The mean umbilical artery pulsatility index was significantly higher in the NT group.

Conclusion

The autonomic nervous system does not seem to play a role in the altered cardiovascular homeostasis in the presence of increased fetal NT. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Surveillance and outcome of fetuses with gastroschisis
Authors: Brantberg A. , Blaas H.‐G. K. , Salvesen K. Å. , Haugen S. E. , Eik‐nes S. H.
Published: February 2004

Objectives

Infants with gastroschisis have a high survival rate. However, the rate (10–15%) of intrauterine fetal death (IUFD) is considerable, and the association with fetal distress is well known. The aim of this study was to describe the outcome of fetuses with a prenatal diagnosis of gastroschisis. The impact of correct prenatal diagnosis, surveillance and signs of complicating risk factors were evaluated.

Methods

All fetuses with prenatally diagnosed gastroschisis at the National Center for Fetal Medicine from January 1988 to August 2002 were registered and prospectively evaluated with regular ultrasound examinations. From 34–36 completed gestational weeks the fetuses were monitored daily to every second day with cardiotocography (CTG).

Results

Gastroschisis was diagnosed in 64 fetuses at a mean gestational age of 19 + 2 weeks. All had normal karyotype. Associated anomalies were found in four cases (6.3%). Three pregnancies (4.7%) were terminated, all for reasons other than gastroschisis. One fetus (1.6%) died in utero. Thirteen fetuses (22%) had abnormal CTG leading to subsequent Cesarean sections. Mean gestational age at delivery was 36 + 1 weeks. Mean birth weight was 2586 g. Thirteen infants (22%) were small for gestational age (SGA). In 15 cases (25%) meconium‐stained amniotic fluid was found; 14 of these had abnormal CTG and/or were SGA. Small bowel atresia was found in four infants (6.7%). Four infants died postnatally at the age of 0–9 months.

Conclusions

CTG surveillance of fetuses with gastroschisis may improve the outcome through detection of fetal distress thereby reducing the risk of IUFD. Other clinical situations of importance that are associated with gastroschisis are described and discussed. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Sonographic measurement of cervical length in twin pregnancies in threatened preterm labor
Authors: Fuchs I. , Tsoi E. , Henrich W. , Dudenhausen J. W. , Nicolaides K. H.
Published: February 2004

Objective

To determine whether sonographic measurement of cervical length in twin pregnancies presenting with threatened preterm labor helps distinguish between true and false labor.

Methods

In 87 women with twin pregnancies presenting with regular and painful uterine contractions at 24–36 (median, 30) weeks of gestation, cervical length was measured by transvaginal ultrasound. Women presenting in active labor, defined by the presence of cervical dilation of 3 cm or more, with ruptured membranes and those who underwent a prior or subsequent cervical cerclage, were excluded from the study. The clinical management was determined by the attending obstetrician without taking into account the cervical length. Primary outcome of the study was delivery within 7 days of presentation.

Results

Delivery within 7 days of presentation occurred in 19/87 (22%) pregnancies and this was inversely related to cervical length, decreasing from 80% (4/5) at 1–5 mm, to 46% (6/13) at 6–10 mm, 29% (4/14) at 11–15 mm, 21% (4/19) at 16–20 mm, 7% (1/15) at 21–25 mm and 0% (0/21) at >25 mm. Logistic regression analysis demonstrated that significant independent contribution in the prediction of delivery within 7 days was provided by cervical length (odds ratio (OR) = 0.78, 95% CI 0.68–0.89, P < 0.001) and use of tocolytics (OR = 0.13, 95% CI 0.02–0.76, P = 0.024), with no significant contribution from gestation at presentation, chorionicity, ethnic origin, maternal age, body mass index, parity, previous history of preterm delivery, cigarette smoking, contraction frequency, vaginal bleeding or the administration of antibiotics or steroids.

Conclusion

In women with twin pregnancies presenting with threatened preterm labor, sonographic measurement of cervical length helps distinguish between those who deliver within 7 days and those who do not. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Sex‐specific antenatal reference growth charts for uncomplicated singleton pregnancies at 15–40 weeks of gestation
Authors: Schwärzler P. , Bland J. M. , Holden D. , Campbell S. , Ville Y.
Published: February 2004

Objective

Female fetuses, on average, weigh less than male fetuses at all gestational ages. The purpose of this study was to compare female and male fetuses in terms of intrauterine ultrasound growth measurements and to develop gestational‐age‐related charts based on a computerized perinatal database.

Methods

This was a retrospective study of unselected women in the second and third trimesters of pregnancy, who had a normal scan at 10–14 weeks. Data analysis was performed using measurements obtained from a mixed‐race population of 4234 women, who underwent 5198 ultrasound examinations. The scans were performed by four trained sonographers, according to a standardized protocol. Routine measurements included biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC) and femur length (FL). The main end‐points were sex‐ and race‐specific differences in fetal biometry, which were also used to estimate fetal weight.

Results

The base‐line demographic characteristics and risk factors were comparable in female and male fetuses. Significant differences in fetal BPD, HC, AC and estimated fetal weight, but not FL, were seen between male and female fetuses. Centile charts for each of these variables were constructed for both male and female fetuses.

Conclusions

This study suggests that small but consistent sex‐related differences in prenatal BPD, HC and AC measurements are established by as early as 15 weeks of gestation. The use of sex‐specific nomograms may improve the prenatal assessment of fetal growth as well as the diagnosis of structural abnormalities. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Crystal Structure, Phase Transition and Ferroelastic Properties of [N(CH3)4]3[As2Cl9]
Authors: Wojtaś M. , Bator G. , Ciunik Z.
Published: February 2004

The crystal structure of [N(CH3)4]3[As2Cl9] is determined at 293 K. It crystallizes in trigonal space group P31c: a = 9.2199(8), c = 21.065(3)Å, Z = 2, R1 = 0.0505, wR2 = 0.1283. The crystal is built of the discrete bioctahedral [As2Cl9]3— anions and the deformed tetramethylammonium cations. A structural phase transition in [N(CH3)4]3[As2Cl9] is detected by the DSC and dilatometric techniques at 146/151 K (on cooling/heating). Dielectric relaxation studies in the frequency range 75 kHz — 5 MHz indicate reorientations of the tetramethylammonium cations within the high temperature phase. Optical observations show the existence of the ferroelastic domain structure below 146 K. The possible mechanism of phase transition is discussed on the basis of the presented results.
Preparation and Crystal Structure of Ni16Si9Al
Authors: Richter Klaus W. , Prots Yurii , Grin Yuri
Published: February 2004

The new ternary phase Ni16Si9Al was synthesized from the elements. The compound is formed in a presumably peritectoid reaction at 786 °C and has a narrow homogeneity range around the nominal composition. It adopts an orthorhombic structure (space group Cmcm) related to Ni3Si2. It was found, that one particular position is occupied by aluminum together with silicon causing slight splitting and thus leading to a local symmetry break in the structure. Both, Ni16Si9Al and Ni3Si2, show related structural motifs and can be described by a combination of flat layers and puckered slabs with interatomic distances indicating covalent interactions between the atoms.
Structure and Thermal Stability of a Novel 2‐D Layered Copper(II) Coordination Polymer with the Bidentate Ligand 1, 2, 4‐Triazol‐5‐one
Authors: Ma Gui Xia , Zhang Tong Lai , Zhang Jian Guo , Yu Kai Bei
Published: February 2004

Single crystals of {[Cu(TO)2(H2O)2](NO3)2}n (TO: 1, 2, 4‐triazol‐5‐one) were grown by slow evaporation from aqueous solution. It crystallizes in the orthorhombic space group Pbca, with a = 7.082(1), b = 10.285(1), c = 17.911(3)Å, V = 1304.6(3)Å3, Z = 4. The CuII distorted octahedra are bridged by bidentate TO ligands into infinite 2‐D interlaced rhombic grid‐like network planes, {[Cu(TO)2(H2O)2]2+}n. Hydrogen bonds, electrostatic interactions, and weak van der Waals' forces assemble these planes and the NO3— anions to a layered structure. The title compound decomposes at 153.4 °C to the final products, Cu(CN)2 and CuO.
Ternary Aluminides with the Ideal Composition A2Pt6Al15 (A = Y, Gd—Tm, Zr)
Authors: Niermann Jens , Jeitschko Wolfgang
Published: February 2004

Ternary rare earth platinum aluminides were prepared by arc‐melting of the elemental components followed by annealing in a high‐frequency furnace. Their crystal structure was determined for the yttrium compound from four‐circle X‐ray diffractometer data. It has hexagonal symmetry with a = 428.1(1) pm, c = 1638.3(3) pm, space group P63/mmc, and was refined to a conventional residual of R = 0.018 for 325 F values and 19 variable parameters. Of the five crystallographic positions, the yttrium position and one of the three aluminum positions show partial occupancies corresponding to the composition Y1.357(3)Pt4Al9.99(2) with the Pearson symbol hP20 — 4.65. These partially occupied sites are that close to each other that at best only one can be fully occupied. A model for an ordered distribution of occupied and unoccupied Y and Al sites requires a √3 larger a axis with the Pearson symbol hP20 — 4.67 for the subcell, very close to the experimental result. Corresponding superstructure reflections could be observed on an image‐plate single‐crystal diffractometer only in the form of diffuse streaks. The compound has the ideal composition Y2Pt6Al15 with Z = 2 for the superstructure. This corresponds to the formula Y1.33Pt4Al10 with Z = 1 for the subcell. The compounds A1.33Pt4Al10 with A = Gd, Tb, Dy, Ho, Er, Tm were found to be isotypic with that of the yttrium compound. This structure is closely related to or isotypic with, respectively, those of Yb2Fe4Si9, Sc1.2Fe4Si9.8, Ce1.2Pt4Ga9.8, Ce2Pt6Ga15, Tb0.67Ni2Ga5—xSix, RE0.67Ni2Ga5—xGex> (with RE = Y, Sm, Ho), and Gd0.67Pt2Al5, reported in earlier investigations. The new compound Zr1.00(1)Pt4Al10.22(3) has nearly the same hexagonal structure with a = 426.1(1) pm and c = 1622.8(3) pm. It was refined from four‐circle diffractometer data to a residual of R = 0.021 for 288 structure factors and 19 variable parameters.
Alkali‐Metal meta‐Hydroxyphenolates: Syntheses and Crystal Structures from Powder X‐Ray Diffraction
Authors: Couhorn Uwe , Dronskowski Richard
Published: February 2004

M[m‐C6H4O(OH)] (M = Li—Cs) have been obtained as highly air‐ and moisture‐sensitive powders from reaction mixtures of the appropriate alkali metals and resorcinol in thf. Both the potassium and rubidium compounds were structurally characterized by means of powder X‐ray diffraction using the Simulated Annealing method and the Rietveld profile refinement technique including C—C/C—O bond distance and C—C—C angle restraints. K[m‐C6H4O(OH)] (orthorhombic P212121) forms infinite alternating chains of meta‐hydroxyphenolate anions connected by K—O bonds and short charge‐assisted hydrogen bonds, thereby generating a three‐dimensional network of corrugated layers similar to the structure of pure resorcinol. The potassium cations are surrounded by a triangle of oxygen and, moreover, coordinated by six adjacent phenylene rings to form a distorted octahedron. The complex crystal structure of Rb[m‐C6H4O(OH)] (monoclinic Pa) is characterized by layers of hydrogen‐bonded meta‐hydroxyphenolate triple units separated by corrugated rubidium layers. The three crystallographically different Rb atoms are coordinated by three, four, and five oxygens with irregular polyhedra, and the rubidiums are also involved in further electrostatic interactions by up to eight phenylene rings.
Konformation und Vernetzung von (CuCN)6‐Ringen in polymeren Cyanocupraten(I) [Cu2(CN)3—] (n= 2, 3)
Authors: Pretsch Thorsten , Brüdgam Irene , Hartl Hans
Published: February 2004

Die Alkalimetall‐tricyano‐dicuprate(I) Rb[Cu2(CN)3] · H2O (1) und Cs[Cu2(CN)3] · H2O (2) wurden hydrothermal aus CuCN und RbCN bzw. CsCN, die Dialkylammonium‐tricyano‐dicuprate(I) [NH2(Me)2][Cu2(CN)3] (3), [NH2(iPr)2][Cu2(CN)3] (4), [NH2(Pr)2][Cu2(CN)3] (5) und [NH2(sekBu)2][Cu2(CN)3] (6) durch Umsetzungen von Dimethylamin, Diisopropylamin, Dipropylamin bzw. Di‐sek‐butylamin mit CuCN und NaCN in Gegenwart von Ameisensäure erhalten. Die Kristallstrukturen dieser sechs Verbindungen enthalten (CuCN)6‐Ringe unterschiedlicher Konformation, die in Abhängigkeit von der Größe und Form der beteiligten Kationen zu Schichten (1) oder dreidimensionalen, teilweise zeolithartigen Netzwerken (2bis6) verbunden sind. Kristalldaten s. Abstract.
Complexes of 2, 6‐Bis(hydroxymethyl)pyridine with Different Copper(II) Salts Involving the Anions Chloride, Perchlorate, Nitrate and Acetate. Synthesis and Crystal Structures of the Complexes
Authors: Winter S. , Seichter W. , Weber E.
Published: February 2004

Complexes of 2, 6‐bis(hydroxymethyl)pyridine (dhmp) with different CuII salts [CuCl2·6H2O, Cu(ClO4)2·6H2O, Cu(NO3)2·3H2O, Cu(CH3COO)2·H2O] are prepared (1—5, respectively), studied by IR, and their crystal structures reported. Dependent on the anion kind, influences on the distortion of the co‐ordination polyhedron, the distribution of donor sites, the formation of a mono‐ or binuclear complex, and the resultant packing structure of the complex are observed, although in no case the counterions of the used CuII salts or water of hydration were found in the co‐ordination sphere. Crystal structures of 1—5 indicate hexaco‐ordination of the CuII ions with N2O4‐environment and show that 1—4 are mononuclear 2:1 (L:M) complexes, but 5 is a binuclear 4:2 complex. Crystallization of Cu(ClO4)2·6H2O with dhmp yielded two different complexes (2/3). In 3, one of the dhmp components is mono‐deprotonated and acts as an anionic ligand. The same behavior is found in 5. Whereas in the neutral ligand complexes 1, 2 and 4 the basal planes are occupied by O donors, and N atoms are in the axial positions of the octahedrons, in 3 and 5 the bases are formed by two O and two N donor atoms, and O atoms are in the axes. Moreover, complex 3 shows the N atoms in trans position, but 5 in cis position. The packing of the cationic complex units is typical of strong and weak H bond interactions involving the counterions and hydroxylic or aromatic hydrogen atoms to yield complex network structures.
Alkali Metal Di‐tert‐butylphenylsilanides — tBu2PhSiM (M = Li, Na, K) — Syntheses, Structures, and Reactivity
Authors: Lerner H.‐W. , Scholz S. , Bolte M. , Wagner M.
Published: February 2004

The alkali metal silanides tBu2PhSiM (M = Li, Na, K) are quantitatively accessible from the reaction of tBu2PhSiBr with alkali metals in heptane, tetrahydrofuran, and benzene at moderately elevated temperature. In contrast to the polymer structure of unsolvated tBu2PhSiNa, the solvated di‐tert‐butylphenylsilanides tBu2PhSiNa(THF), tBu2PhSiK(C6H6), tBu2PhSiK(THF), and tBu2PhSiK(THF)2 possess a novel feature in their crystal structures with a dimeric arrangement of tBu2PhSiM units via π interaction between the tBu2PhSi group and the alkali metal centers. The alkali metal siloxides tBu2PhSiOM (M = Li, Na, K) can be synthesized almost quantitatively from tBu2PhSiM (M = Li, Na, K) with N2O in tetrahydrofuran at —78 °C. Single crystals of the silanol tBu2PhSiOH have been obtained from the protolysis of tBu2PhSiONa with (NH4)2SO4.
Phosphanimin‐ und Phosphaniminato‐Komplexe von Beryllium. Kristallstrukturen von [BeCl2(HNPPh3)2], [BeCl(HNPPh3)2(Py)]Cl und [Be3Cl2(NPPh3)4]
Authors: Neumüller Bernhard , Dehnicke Kurt
Published: February 2004

Tetraphenylphosphonium‐hexachlorodiberyllat, (Ph4P)2[Be2Cl6], reagiert mit Lithiumphosphaniminat, [LiNPPh3]6, in Dichlormethan unter Bildung des dreikernigen Berylliumphosphaniminats [Be3Cl2(NPPh3)4] (3). Als Nebenprodukt erhält man den Phosphaniminkomplex [BeCl2(HNPPh3)2] (1), der mit Pyridin in den ionischen Komplex [BeCl(HNPPh3)2(Py)]Cl (2) umgewandelt wird. Dagegen reagiert das silylierte Phosphanimin Me3SiNP(p‐Tolyl)3 (5) weder mit BeCl2 noch mit (Ph4P)2[Be2Cl6] unter Bildung von Phosphaniminaten des Berylliums. Aus CH2Cl2‐Lösung läßt sich lediglich das Aminophosphoniumsalz [(C7H7)3PNH2]Cl (4) isolieren. Die Verbindungen 1‐5 werden durch Kristallstrukturanalysen und durch IR‐Spektroskopie charakterisiert.

1·C7H8: Raumgruppe C2/c, Z = 4, Gitterkonstanten bei 193 K: a = 1408, 9(2); b = 1750, 9(2); c = 1633, 2(2) pm; β = 106, 50(1)°; R1 = 0, 0385. Die Molekülstruktur von 1 weist kurze Be—N‐Abstände von 169, 8(3) pm auf.

2·Py: Raumgruppe P1¯, Z = 4, Gitterkonstanten bei 193 K: a = 969, 5(1); b = 2077, 1(2); c = 2266, 4(2) pm; α = 72, 24(1)°; β = 87, 16(1)°; γ = 77, 42(2)°; R1 = 0, 0776. 2 hat die Struktur eines Ionenpaars, in dem die NH‐Atome der Phosphanimin‐Liganden Wasserstoffbrückenbindungen mit dem Chloridion ausbilden. Die HNPPh3‐Moleküle realisieren kurze Be—N‐Bindungen von 169, 0(6) pm, der Be—N‐Abstand des Pyridinliganden beträgt 182, 5(6) pm.

3·3CH2Cl2: Raumgruppe P1¯, Z = 2, Gitterkonstanten bei 193 K: a = 1333, 2(2); b = 1370, 2(2); c = 2151, 8(3) pm; α = 107, 14(1)°; β = 91, 39(1)°; γ = 105, 15(1)°; R1 = 0, 0917. Die Struktur des dreikernigen Moleküls 3 entspricht der eines Be2+‐Ions, das durch die N‐Atome zweier Chelatliganden {ClBe(NPPh3)2}— tetraedrisch koordiniert ist.

4·CH2Cl2: Raumgruppe P21/c, Z = 4, Gitterkonstanten bei 193 K: a = 1206, 6(2); b = 1798, 0(2); c = 1096, 2(1) pm; β = 97, 65(1)°; R1 = 0, 0535. 4 bildet dimere Einheiten, in denen die NH2‐Gruppen der [(C7H7)3PNH2]+‐Kationen mit den Chloridionen zentrosymmetrische Achtringe bilden.

5: Raumgruppe P21/n, Z = 4, Gitterkonstanten bei 193 K: a = 1074, 3(2); b = 2132, 2(3); c = 1075, 5(2) pm; β = 110, 68(1)°; R1 = 0, 0664. 5 bildet Moleküle mit Abständen PN von 154, 6(3), SiN von 168, 8(3) pm und einem SiNP‐Winkel von 134, 4(2)°.
Festkörper‐NMR‐Untersuchungen an Natriumoxothiophosphaten(V)
Authors: Pompetzki M. , van Wüllen L. , Jansen M.
Published: February 2004

Natriummonothiophosphat(V) Na3PO3S ist dimorph. Die metastabile Hochtemperaturmodifikation β‐Na3PO3S kristallisiert hexagonal mit den Gitterkonstanten a = 8, 996(4) und c = 5, 216(2)Å. 31P‐Festkörper‐NMR‐Experimenten zufolge weist α‐Na3PO3S bei 20 °C im Gegensatz zu den Ergebnissen der verfeinerten Kristallstruktur eine nichtaxialsymmetrische Umgebung für die Phosphorkerne auf. Diese Diskrepanz wird unter der Annahme geordneter und fehlgeordneter Strukturmodelle diskutiert. Bei 490 °C hingegen ist der Tensor der chemischen Verschiebung für die Phosphorkerne in α‐Na3PO3S axialsymmetrisch. Offenbar wird die Verzerrung der Phosphorumgebung durch die thermische Bewegung der Atome aufgehoben. Die Anzahl kristallographischer Lagen für Natrium und Phosphor in Na3PO2S2 und Na3POS3 läßt sich anhand von Festkörper‐NMR‐Spektren in exakter Übereinstimmung mit ihren Kristallstrukturen bestimmen.
Structural Isomers of Bis(diphenylarsino)methane‐dichloroplatinum(II)
Authors: Babai Arash , Deacon Glen B. , Meyer Gerd
Published: February 2004

From a range of preparative methods, three geometric isomers of bis(diphenylarsino)methane‐dichloroplatinum(II) have been isolated, viz. cis‐PtCl2(dpam), trans, trans‐Pt2Cl4(dpam)2 and cis, trans‐Pt2Cl4(dpam)2. Their structures were determined by single‐crystal X‐ray diffraction.
Syntheses, Characterization and X‐Ray Structures of the first Copper(I) and Silver(I) Complexes with ATT (ATT = 6‐Aza‐2‐thiothymine)
Authors: Ghassemzadeh Mitra , Pooramini Mostafa Mohammad , Tabatabaee Maasoomeh , Heravid Majid M. , Neumüller Bernhard
Published: February 2004

The reaction of copper(I) chloride with 6‐aza‐2‐thiothymine (ATT, 1) and triphenylphosphane in methanol/chloroform gives [(ATT)CuCl(PPh3)] (2) as a neutral complex. [(ATT)Ag(NO3)(PPh3)2]·MeOH (3) can be obtained by the reaction of 1 with silver(I) nitrate and triphenylphosphane in methanol/chloroform in excellent yields and the single crystals of 3 can be obtained from acetonitril solution.

Both complexes were characterized by infrared spectroscopy, elemental analyses as well as by X‐ray diffraction studies. Crystal data for 2 at —80 °C: space group I2/a with a = 1859.3(1), b = 1143.2(1), c = 2208.2(1) pm, β = 104.84(1)°, Z = 8, R1 = 0.0355 and for 3 at —80 °C: space group P21/c with a = 1344.1(1), b = 1553.6(1), c = 1977, 3(3) pm, β = 105.26(1)°, Z = 4, R1 = 0.0436.
Reactions of Ru3(CO)12 with Diphosphenes — A New Route to 50‐Electron Ru3P2nido‐Clusters
Authors: Freytag Matthias , Edelmann Frank T. , Ernst Ludger , Jones Peter G. , Schmutzler Reinhard
Published: February 2004

The reaction of the symmetric diphosphene 2, 4, 6‐(CF3)3‐C6H2‐P=P‐C6H2‐2, 4, 6‐(CF3)3 4 with Ru3(CO)12 led to the 50‐electron Ru3P2 nido‐cluster Ru3(CO)9[μ‐P‐C6H2‐2, 4, 6‐(CF3)3]2 5, which in solution at room temperature displays hindered rotation of the aromatic rings about the C(aryl)—P bonds. The structure of 5 was determined by X‐ray crystal structure analysis; its Ru3P2 centre forms a distorted square pyramid with one ruthenium atom at the apex. One of the two C6H2(CF3)3 groups is also appreciably distorted. Temperature‐dependent 19F NMR studies of the [A3M3X]2 spin system (A = M = CF3, X = 31P) of 5 indicated a rotational barrier ΔG≠ of 82.3 kJ mol‐1 at 141 °C. The same Ru3P2 core was obtained by the reaction of the unsymmetric diphosphene Mes*‐P=P‐Mes 11 with Ru3(CO)12; hindered rotation about the C(aryl)—P bonds was also observed, in this case.
Synthesis, Spectral and Magnetic Properties, and Crystal Structures of Copper(II) Pyridinecarboxylate Adducts with N‐Heterocyclic Ligands
Authors: Segl'a Peter , Palicová Martina , Miklos Dusan , Koman Marian , Melník Milan , Korabik Maria , Mrozinski Jerzy , Glowiak Tadeusz , Sundberg Markku R. , Lönnecke Peter
Published: February 2004

Synthesis and characterization of seven new complexes [Cu(2‐MeSnic)2(CH3OH)]2 (where 2‐MeSnic is 2‐methylthionicotinate), [Cu(2‐MeSnic)2L2]2 (where L is pyridine — py, ethylnicotinate — Etnic and butylnicotinate — Bunic), [Cu(2‐MeSnic)2L2(H2O)2] (where L is py and nicotinamide — nia) and [Cu(2‐MeSnic)2(N‐Menia)2(H2O)2]·2H2O (where N‐Menia is N‐methylnicotinamide) are reported. The characterization were based on elemental analysis, infrared, electronic and EPR spectra, and magnetic susceptibility measurements over a temperature range of 1.8 — 300 K or 70 — 300 K. Three complexes of different type were studied by X‐ray analysis. The molecule of [Cu(2‐MeSnic)2(CH3OH)]2 has dimeric paddle‐wheel cage structure with a tetragonal pyramidal arrangement around CuII. The dimer results from the fact that carboxyl groups of four 2‐MeSnic anions function as bridging in a syn‐syn arrangement. On the other hand [Cu(2‐MeSnic)2(py)2]2 forms dimers with hexacoordinated CuII atoms in highly distorted coordination octahedra, each with two oxygen atoms of bridging carboxyl groups in an anti‐anti arrangement of two 2‐MeSnic anions, with two oxygen atoms of one asymmetrically chelating 2‐MeSnic anion and with two nitrogen atoms of two pyridine ligands. The temperature independent EPR spectrum for this complex exhibits an axial signal which corresponds to almost isolated S = 1/2 magnetic ions. Magnetic data for the dimer show a weak antiferromagnetic interaction between the two metal ions with J = —0.65 cm—1. The CuII atom in complex [Cu(2‐MeSnic)2(py)2(H2O)2] is hexacoordinated in an elongated centrosymmetrical tetragonal‐bipyramidal arrangement (4 + 2). Based on the molecular structure the electronic, infrared, electron paramagnetic resonance spectra and magnetic properties are discussed and stereochemistry as well as the mode of ligand coordination in new solid complexes under study have been determined.
Vibrational Spectra and Magnetic Properties of Eu3[BN2]2 and LiEu4[BN2]3
Authors: Somer Mehmet , Gül Cem , Müllmann Ralf , Mosel Bernd D. , Kremer Reinhard K. , Pöttgen Rainer
Published: February 2004

Eu3[BN2]2 and LiEu4[BN2]3 were synthesized from a stoichiometric mixture of EuN, BN, europium metal and Li3N, EuN and BN (ratio: 1:4:3) in sealed niobium ampoules at 1475 and 1275 K, respectively. Temperature dependent susceptibility measurements of Eu3[BN2]2 and LiEu4[BN2]3 show Curie‐Weiss behavior with experimental magnetic moments of 8.03(5) and 8.5(1) μB/Eu atom, respectively, compatible with divalent europium. Both nitridoborates order ferromagnetically at TC = 32.0(5) K (Eu3[BN2]2) and 22.0(5) K (LiEu4[BN2]3). The saturation magnetizations of 5.73(5) μB/Eu atom at 5 K and 7 T for Eu3[BN2]2 and 4.2 μB/Eu atom at 5 K and 2 T for LiEu4(BN2)3 are smaller than the maximum value of 7 μB. 151Eu Mössbauer data of Eu3[BN2]2 at 4.2 K show an isomer shift of —11.4(1) mm/s and an experimental line width of 3.1(2) mm/s. Full magnetic hyperfine field splitting with 26.2(3) T at the europium nuclei is detected. Vibrational spectra of Eu3[BN2]2 are interpreted on the basis of discrete [BN2]3— units with symmetry D∞h by taking into account the existence of two crystallographically independent [BN2]3— anions and their dynamic coupling in the unit cell (factor group splitting).
Dithiolylium‐Chlorooxomolybdate(V): Synthese und Kristallstruktur von (C3Cl3S2)[MoOCl4] und (C3Cl3S2)[Mo2O2Cl7]
Authors: Beck Johannes , Koch M.
Published: February 2004

Durch Umsetzung von 3, 4, 5‐Trichlor‐1, 2‐dithiolyliumchlorid mit MoOCl3 in Dichlormethan unter solvothermalen Bedingungen bei 65 °C entstehen nebeneinander das grüne Tetrachlorooxomolybdat(V) (C3Cl3S2)[MoOCl4] und das braun‐gelbe Heptachlorodioxodimolybdat(V) (C3Cl3S2)[Mo2O2Cl7]. Die Kristallstrukturen beider Substanzen enthalten annähernd planare (C3Cl3S2)+‐Ionen mit einer S—S‐Bindungslänge von 203 pm. Das diskrete [MoOCl4]—‐Ion in der Struktur von (C3Cl3S2)[MoOCl4] hat die Form einer quadratischen Pyramide mit einer Grundfläche aus Chloratomen, aus der das zentrale Molybdänatom um 58 pm in Richtung des Sauerstoffatoms auf der Pyramidenspitze herausgerückt ist. Das [Mo2O2Cl7]—‐Ion in der Struktur von (C3Cl3S2)[Mo2O2Cl7] hat die Form eines flächenverknüpften Oktaederdoppels. Es besteht formal aus einem [MoOCl4]—‐Ion und einem MoOCl3‐Molekül, die durch eine symmetrische und zwei asymmetrische Chlorobrücken verknüpft sind. Die Molybdänatome in den so verknüpften Oktaedern bilden bei einem Abstand von 357 pm keine Bindung aus.