Tautomeric equilibrium between penta- and hexacoordinate silicon chelates. A chloride bridge between two pentacoordinate silicons.

The reaction of O-trimethylsilyl-1,1-dimethyl-2-trifluoroacetylhydrazine (1a) with chloromethyl(methyl)dichlorosilane affords an unexpected equilibrium mixture, 10a right arrow over left arrow 11a, between a neutral hexacoordinate silicon chelate with a covalent chloro ligand (10a) and an ionic pentacoordinate silicon complex (11a). The equilibrium reaction consists formally of a migration of the covalent chloro ligand from silicon to an adjacent ammonium nitrogen, as a chloride anion, and thus constitutes a novel type of tautomeric reaction. Crystallographic and NMR data provide evidence for the reaction.

(MeLi)4(dem)1.5]infinity] and [(thf)3Li3M3[(NtBu)3S--how to reduce aggregation of parent methyllithium.

Organolithium compounds play the leading role among the organometallic reagents in synthesis and in industrial processes. Up to date industrial application of methyllithium is limited because it is only soluble in diethyl ether, which amplifies various hazards in large-scale processes. However, most reactions require polar solvents like diethyl ether or THF to disassemble parent organolithium oligomers.

Reaction of RGeBr (R=iPr C H NSiMe ) with Ammonia To Give (RGe) (NH ) (NH): A Compound Containing Terminal NH Groups.

The surprisingly facile preparation of (RGe) (NH ) (NH) (1; R=iPr C H NSiMe ), which contains one NH and four NH groups, is achieved by the introduction of gaseous ammonia into a solution of iPr C H NSiMe GeBr in diethyl ether.

Metoprolol in high renin hypertension. A comparison with propranolol.

The effects of two beta-adrenoceptor blockers, the beta1-selective metoprolol and the non-selective propranolol, was studied in high renin patients (n = 15) with very high pretreatment blood pressures. Ten of the patients had essential hypertension and five renal artery stenosis. From high blood pressure values after six weeks on placebo, there was a pronounced drop in both supine and standing blood pressures in both groups with a small to moderate dose of beta-blocker, thus showing that the good blood pressure control in high renin patients is not connected to blockade of beta2-receptors or to the aetiology of the hypertension.

A longitudinal study of bone-mineral content and intestinal calcium absorption in patients with chronic renal failure.

In 14 nondialyzed patients with chronic renal failure (CRF) and at the start of treatment a glomerular filtration rate (GFR) of 14--47 ml/min changes in bone mineral mass (BMM), expressed in percentage of the initial value, showed a significant correlation with the mean GFR during an observation period of 16 +/- 2 mo. During a predialysis period of 6 mo BMM decreased to 97.8 +/- 3.