Reexamination of hexafluorosilicate hydrolysis by 19F NMR and pH measurement.

The dissociation of hexafluorosilicate has been reinvestigated due to recent suggestions that fluorosilicate intermediates may be present in appreciable concentrations in drinking water. 19F NMR spectroscopy has been used to search for intermediates in the hydrolysis of hexafluorosilicate. No intermediates were observable at 10(-5) M concentrations under excess fluoride forcing conditions over the pH range of 3.

Three structural roles for water in bone observed by solid-state NMR.

Hydrogen-bearing species in the bone mineral environment were investigated using solid-state NMR spectroscopy of powdered bone, deproteinated bone, and B-type carbonated apatite. Using magic-angle spinning and cross-polarization techniques three types of structurally-bound water were observed in these materials. Two of these water types occupy vacancies within the apatitic mineral crystal in synthetic carbonated apatite and deproteinated bone and serve to stabilize these defect-containing crystals.

Highly ordered interstitial water observed in bone by nuclear magnetic resonance.

Unlabelled: NMR was used to study the nanostructure of bone tissue. Distance measurements show that the first water layer at the surface of the mineral in cortical bone is structured. This water may serve to couple the mineral to the organic matrix and may play a role in deformation.

Synthesis of a digermane-containing tricylic nonadecadienedione incorporating an equivalent of ring-opened THF.

The combination of 2 equiv of bis[bis(trimethylsilyl)amide]germylene (5) with 2 equiv of 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) in tetrahydrofuran (THF) results in the ring-opening of 1 equiv of THF to form 2,2,8,8-tetrakis(1,1,1,3,3,3-hexamethyl-disilazan-2-yl)-5,16-diphenyl-7,9,14-trioxa-1,3,5,16,18,19-hexaaza-2,8-digerma-tricyclo[13.2.1.

Comparison of "polynaphthalenes" prepared by two mechanistically distinct routes.

The Bergman cyclization has long been known to produce polymers as side products. More recently, this attribute has been harnessed for the production of conjugated materials. However, the structures of these polymers have not been established.