Metal salts phosphonate structure

Metal phosphonates are usually prepared by reaction of phosphonic acids with metal salts under hydrothermd conditions [5-7]. Layered structures are predominant for most metals, the organic group being oriented more or... 

Layered metal IV phosphonates are widely used, particularly zirconium phosphonates, because their synthesis is versatile and their structural arrangement may be tailored to applications. Zirconium phosphonates are usually prepared by heating an aqueous solution of a metal IV salt (e.g., ZrOCl2) with a phosphonic acid at 60-80 °C synthesis in the presence of HP permits one to increase significantly the crystallinity of the final products. 

Several electrophilic substitution reactions have employed dimethyl (diazomethyl)-phosphonate, methyl (diazomethyl)phenylphosphinate (10 R = Ph, = Me, R = H) or (diazomethyl)diphenylphosphine oxide, as either a metal salt or the free acid in combination with Et3N. Thus, 22 Yields 23 24 gives 25 (Z = Br) " and 26 gives a mixture of 25 (Z = OR, R = Me, Pr, CH2Ph, etc.) and 27 (Z = OR) the structural isomer 27 (Z = Br) not being obtained from 24 ". ... 

The imine compounds are then reacted with metal salts of dialkyl phosphonates with formula 4 to yield secondary aminophosphonates 5. Reduction of the secondary aminophosphonates furnished the corresponding aminophosphonates having structure 6. 

Dialkyl H-phosphonates furnish in general two types of metal salts alter appropriate treatment. The first type is obtained through deprotonation of the hydrogen atom of the P-H group and has a phosphite structure. 

The other type of metal salt is prepared via dealkylation of one or two alkyl substituents of the alkoxy groups of the dialkyl H-phosphonate. These salts retain their phosphonate structure since the immediate surrounding of the tetrahedral phosphorus atom remains unchanged. 

In this section, the alkaline metal derivatives of the first type of metal salts of dialkyl H-phosphonates are described, namely, those having phosphite structure. The reactivity of these metal salts has been already discussed in the preceding chapters, since in most of the cases they are generated as intermediates and used in situ as phosphorylation reagents. 

These metal salts retain the phosphonate structure of the starting dialkyl H-phosphonates, which is characterized by a four-coordinated phosphorus atom in the O3PH fragment. They can be prepared in one of the following methods ... 

Some IIF or IIG had good herbicidal activity against dicotyledonous weeds just like those of alkali metal salts of 0-alkyl 1-(substituted phenoxyacetoxyjalkyl-phosphonic acids and 0,0-dialkyl 1-(substituted phenoxyacetoxyjalkylphospho-nates. llG-6 (R =Na, R =H, R =Ph, Yn=2,4-Cl2 in the structure lo) showed best post-emergence inhibitory effect (90-100 %) comparable to IC-22 (clacyfos) against three tested dicotyledonous weeds. 

Multilayers of Diphosphates. One way to find surface reactions that may lead to the formation of SAMs is to look for reactions that result in an insoluble salt. This is the case for phosphate monolayers, based on their highly insoluble salts with tetravalent transition metal ions. In these salts, the phosphates form layer structures, one OH group sticking to either side. Thus, replacing the OH with an alkyl chain to form the alkyl phosphonic acid was expected to result in a bilayer structure with alkyl chains extending from both sides of the metal phosphate sheet (335). When zirconium (TV) is used the distance between next neighbor alkyl chains is 0.53 nm, which forces either chain disorder or chain tilt so that VDW attractive interactions can be reestablished. 

Heterobimetallic catalysis mediated by LnMB complexes (Structures 2 and 22) represents the first highly efficient asymmetric catalytic approach to both a-hydro and c-amino phosphonates [112], The highly enantioselective hydrophosphonylation of aldehydes [170] and acyclic and cyclic imines [171] has been achieved. The proposed catalytic cycle for the hydrophosphonylation of acyclic imines is shown representatively in Scheme 10. Potassium dimethyl phosphite is initially generated by the deprotonation of dimethyl phosphite with LnPB and immediately coordinates to the rare earth metal center via the oxygen. This adduct then produces with the incoming imine an optically active potassium salt of the a-amino phosphonate, which leads via proton-exchange reaction to an a-amino phosphonate and LnPB. 

In contrast to the conventional approach whereby various organic groups are subsequently bound to a previously prepared surface, we have been synthesizing a broad series of anchored, layered-structure solids by precipitating the pre-derived phosphonate salts with tetravalent metal ions. The two-dimensional backbone has the zirconium phosphate structure however, substituted for hydroxylic groups are the desired organics, oriented away from the basal surfaces in a bilayered fashion in the interlayer region. 

Polyethylene oxides and polyethyleneimines are of great interest because of their ability to form a wide variety of metal and salt complexes. We have anchored polyethylene oxide oligomers (n=l-33) and polyimines (n=l-4) to zirconium phosphate type layers. The polymers are first converted to phosphates or phosphonates which in turn react with Zr(IV) solutions to form the layered derivatives. Cross-linking of the layers has also been accomplished. Preliminary structural and complexing behavior of these layered materials is presented. It is demonstrated that the NaSCN-polyethyleneoxide... 

Phosphonate salte of tetravalent, trivalent, and divalent metal ions contain strong ionic-covalent bonds within the metal-oxygen sheets that determine the details of their lamellar structures. Tbe divalent metal (Zn2+ and Cu2+) compounds can be made nanoporous by various techniques, and subsequent intercalation by small molecules such as ammonia, amines, and other small molecules forms the basis for size- and shiqw-selective piezoelectric sensors. Several techniques have been developed for depositing these materials as thin Hlms on quartz crystal microbalance (QCM) devices. The most successful of these, in terms of eliminating interferences and speed of device response, involves layer-by-layer growth of films through adsorption of their components from non-aqueous solutions. 

---