Synthesis, Structure, and Molecular Orbital Studies of Yttrium, Erbium, and Lutetium Complexes Bearing eta(2)-Pyrazolato Ligands: Development of a New Class of Precursors for Doping Semiconductors.

Treatment of yttrium metal with bis(pentafluorophenyl)mercury (1.5 equiv), 3,5-di-tert-butylpyrazole (3 equiv), and pyridine (2 equiv) in toluene at ambient temperature for 120 h afforded tris(3,5-di-tert-butylpyrazolato)bis(pyridine)yttrium(III) (33%). In an analogous procedure, the reaction of erbium metal with 3,5-dialkylpyrazole (alkyl = methyl or tert-butyl), bis(pentafluorophenyl)mercury, and a neutral nitrogen donor (4-tert-butylpyridine, pyridine, n-butylimidazole, or 3,5-di-tert-butylpyrazole) yielded tris(3,5-di-tert-butylpyrazolato)bis(4-tert-butylpyridine)erbium(III) (63%), tris(3,5-di-tert-butylpyrazolato)bis(pyridine)erbium(III) (88%), tris(3,5-di-tert-butylpyrazolato)bis(n-butylimidazole)erbium(III) (48%), tris(3,5-dimethylpyrazolato)bis(4-tert-butylpyridine)erbium(III) (50%), and tris(3,5-di-tert-butylpyrazolato)(3,5-di-tert-butylpyrazole)erbium(III) (59%), respectively. Treatment of tris(cyclopentadienyl)lutetium(III) or tris(cyclopentadienyl)erbium(III) with 3,5-di-tert-butylpyrazole (3 equiv) and 4-tert-butylpyridine (2 equiv) in toluene at ambient temperature for 24 h afforded tris(3,5-di-tert-butylpyrazolato)bis(4-tert-butylpyridine)lutetium(III) (83%) and tris(3,5-di-tert-butylpyrazolato)bis(4-tert-butylpyridine)erbium(III) (41%), respectively. The X-ray crystal structures of all new complexes were determined. The X-ray structure analyses revealed seven- and eight-coordinate lanthanide complexes with all-nitrogen coordination spheres and eta(2)-pyrazolato ligands. Molecular orbital calculations were carried out on dichloro(pyrazolato)diammineyttrium(III). The calculations demonstrate that eta(2)-bonding of the pyrazolato ligand is favored over the eta(1)-bonding mode and give insight into the bonding between yttrium and the pyrazolato ligands. Complexes bearing 3,5-di-tert-butylpyrazolato ligands can be obtained in a high state of purity and sublime without decomposition (150 degrees C, 0.1 mmHg). Application of these complexes as source compounds for chemical vapor deposition processes is discussed.

Extrinsic bronchial compression due to patent ductus arteriosus closure device.

Interventional cardiology provides a valuable nonoperative approach for the modern management of patent ductus arteriosus (PDA) in patients with non-complex congenital heart disease. We describe a patient with a right-sided aortic arch who developed severe bronchomalacia after PDA device closure that necessitated extensive surgical repair. Consequently, we advise that in infants with a right-sided aortic arch and PDA inserting into the right pulmonary artery, device closure is challenging due to the potential risk of bronchial compression and subsequent development of bronchomalacia. Consideration should be given to surgical closure or use of a softer duct occlusion device.

Congenital aneurysm of the muscular interventricular septum in association with cardiac arrhythmias and a chromosomal abnormality.

We report a newborn with a congenital aneurysm of the muscular interventricular septum, a conduction system abnormality involving variable left and right bundle branch block, and an abnormality of the short arm of chromosome 20, This combination of anomalies has not been previously reported. To date, the infant has progressed well from a cardiac perspective but has poor muscle tone and developmental delay.

Percutaneous closure of postoperative ventricular septal defects with the Amplatzer device.

The objective of this study was to look at the procedure, the results, and the follow-up of patients who underwent percutaneous closure of a residual ventricular septal defect (VSD) following a surgical closure using the Amplatzer VSD device. Four patients had an original diagnosis of tetralogy of Fallot, two patients had a patch leak following a surgical repair of a VSD, and three patients had a VSD not repaired at the time of surgery. All patients fulfilled the currently accepted surgical criterion for reoperation (Qp/Qs>1.5). The mean Qp/Qs was 1.8+/-0.3 (1.5-2.3). Four patients underwent VSD closure using an Amplatzer perimembranous VSD device and in five patients an Amplatzer muscular VSD device was implanted. We performed percutaneous closure in nine patients. The size of the residual shunt ranged from 6 to 14 mm and the size of device used ranged from 8 to 16 mm. The arteriovenous loop needed to be recreated in two patients because of failure to advance the delivery sheath. There was complete closure of the defect in six cases, and a small residual shunt remained in three cases. Percutaneous closure of postoperative VSDs appears to be an effective way to resolve a hemodynamically significant residual shunt. There were no difficulties encountered with implantation of the devices. These promising short-term results need reinforcement with additional long-term data.