Reaction of tungsten-phosphinidene and -arsinidene complexes with carbodiimides and alkyl azides: a straightforward way to four-membered heterocycles.

The reaction of the phosphinidene and arsinidene complexes [Cp*E{W(CO)5 }2 ] (E=P (1 a), As (1 b); Cp*=C5 Me5 ) with carbodiimides leads to the new four-membered heterocycles of the type [Cp*C(NR)2 E{W(CO)5 }2 ] (E=P: R=iPr (2 a), Cy (3 a); E=As: R=iPr (2 b), Cy (3 b)). The reaction of phosphinidene complex 1 a with alkyl azides yields the triazaphosphete derivatives [Cp*P{W(CO)5 }N(R)NN{W(CO)5 }] (R=Hex, Cy) (4). These unprecedented N3 P four-membered triazaphosphete complexes can be regarded as stabilized intermediates of the Staudinger reaction, which have not been previously isolated.

The complexed 1,3-diphospha-2-arsaallyl radical and its cationic and anionic derivatives.

Photolysis of [Cp*As{W(CO)(5)}(2)] (1a) in the presence of Mes*P=PMes* (Mes*=2,4,6-tri-tert-butylphenyl) leads to the novel 1,3-diphospha-2-arsaallyl radical [(CO)(5)W(mu,eta(2):eta(1)-P(2)AsMes*(2))W(CO)(4)] (2a). The frontier orbitals of the radical 2a are indicative of a stable pi-allylic system that is only marginally influenced by the d orbitals of the two tungsten atoms. The SOMO and the corresponding spin density distribution of the radical 2a show that the unpaired electron is preferentially located at the two equivalent terminal phosphorus atoms, which has been confirmed by EPR spectroscopy.

1,2,3-triphosphole derivatives as reactive intermediates.

The complexes [Cp*E{W(CO)5}2] (E=P, As; Cp*=C5Me5) react with 1,2-diphosphinobenzene to give 1,2,3-triphosphole and 2-arsa-1,3-diphosphole derivatives as reactive intermediates that dimerise to polycyclic phosphorous and arsenic containing cage compounds.

The complexed triphosphaallyl radical, cation, and anion family.

Radically complex: The photolytic reaction of [Cp*P{W(CO)(5)}(2)] (Cp* = C(5)Me(5)) with a diphosphene produces, via a radical intermediate, an air-stable complexed triphosphaallyl radical, in which the unpaired electron is evenly distributed over both terminal P atoms. Oxidation of the radical leads to a triphosphaallyl cation, which is only stable at low temperatures in solution, whereas the stable triphosphaallyl anion is formed by reduction (see picture, Mes* = 2,4,6-tri-tert-butylphenyl).

Reactivity of transition metal-phosphorus triple bonds towards triply bonded [{CpMo(CO)2}2]: formation of heteronuclear cluster compounds.

Thermolysis of [Cp*P{W(CO)5}2] (1) in the presence of [{CpMo(CO)2}2] leads to the novel complexes [{(CO)2Cp*W}{CpMo(CO)2}(micro,eta2:eta1:eta1-P2{W(CO)5}2)] (6; Cp=eta5-C5H5, Cp*=eta5-C5Me5), [{(micro-O)(CpMoWCp*)W(CO)4}{micro3-PW(CO)5}2] (7), [{CpMo(CO)2}2{Cp*W(CO)2}{micro3-PW(CO)5}] (8) and [{CpMo(CO)2}2{Cp*W(CO)2}(micro3-P)] (9). The structural framework of the main products 8 and 9 can be described as a tetrahedral Mo2WP unit that is formed by a cyclisation reaction of [{CpMo(CO)2}2] with an [Cp*(CO)2W[triple chemical bond]P-->W(CO)5] intermediate containing a W--P triple bond and subsequent metal-metal and metal-phosphorus bond formation. Photolysis of 1 in the presence of [{CpMo(CO)2}2] gives 8, 9 and phosphinidene complex [(micro3-PW(CO)5){CpMo(CO)2W(CO)5}] (10), in which the P atom is in a nearly trigonal-planar coordination environment formed by one {CpMo(CO)2} and two {W(CO)5} units.

CT and endoscopic ultrasound in comparison to endoluminal MRI: preliminary results in staging gastric carcinoma.

Purpose: To prospectively compare diagnostic parameters of a newly developed endoluminal MRI (endo-MRI) concept with endoscopic ultrasound (EUS) and hydro-computer tomography (Hydro-CT) in T-staging of gastric carcinoma on one patient collective.

Material And Methods: 28 consecutive patients (11 females, 17 males, age range 46-87 years, median 67 years) referred for surgery due to a gastric malignancy were included. Preoperative staging by EUS was performed in 14 cases and by Hydro-CT in 14 cases within a time frame of 2 weeks.

Magnetic resonance imaging for local staging of gastric carcinoma: results of an in vitro study.

Objective: Preoperative staging of gastric carcinoma is limited by the fact that available imaging modalities do not enable accurate evaluation of the depth of infiltration of the gastric wall. The aim of this study was to evaluate the efficiency of conventional magnetic resonance imaging (MRI) in local staging of gastric carcinoma.

Methods: Sixty-five specimens of patients with proven gastric carcinoma were examined immediately after gastrectomy.

New coil concept for endoluminal MR imaging: initial results in staging of gastric carcinoma in correlation with histopathology.

Our aim was to conduct a prospective study to evaluate staging accuracy of a new coil concept for endoluminal magnetic resonance imaging (MRI) on ex vivo gastric carcinomas. Twenty-eight consecutive patients referred to surgery with a clinically proven primary gastric malignancy were included. Surgical specimens were examined with a foldable and self-expanding loop coil (8-cm diameter) at 1.

Prospective comparison of endoscopy, endosonography and computed tomography for staging of tumours of the oesophagus and gastric cardia.

Background: Local and multimodal therapeutic strategies for tumours of the oesophagus and gastric cardia, require precise preoperative staging. Endosonography is considered the most accurate staging method, while computed tomography (CT) has limitations especially in the evaluation of local infiltration. Macroscopic endoscopic evaluation was reported to be accurate in selected series, but no study has yet compared all three staging modalities.