Poly hydrides

Photolysis of Transition-Metal Poly hydride Complexes 363... 

Three years ago, while we were considering possible reasons for the general inability of transition metals to insert into and activate C-H bonds, our attention turned to the question of the instability of transition metal alkyl hydride complexes. We have listed the few alkyl hydride complexes of which we are aware (i) (one additional case (2) recently came to our attention) as well as some of the only slightly more numerous cases of substituted alkyl hydrides stabilized by chelation (3). In contrast, there are enormous numbers of polyalkyls (4, 5) and poly hydrides (6). While rarity does not logically imply instability, it does suggest it, so we considered possible mechanistic explanations for the assumed rapid decomposition of ci -MLn(R)(H) relative to cis-MLnR2 and cis-MLnH2. We have focused on octahedral complexes since they are both more important and more numerous. 

Heterobimetallic complexes have recently attracted considerable attention in light of the promise of enhanced reactivity as a result of the cooperativity between adjacent, but electronically different, metal centers. A large number of these bimetallic compounds have been synthesized by the reactions of organometallic halides with anionic metal carbonyls. Here, we describe an extension of this route to the synthesis of hydride rich. Os—Zr and Os—Rh complexes by the reaction of organometallic halides with a metal poly hydride anion. These preparations demonstrate the synthetic utility of transition metal polyhydride anions. 

Reduction of poly(vinyl chloride) with lithium aluminium hydride. 

The hydrides are usually prepared by reducing an organotin chloride, alkoxide, or oxide with lithium aliuninum hydride or with poly(methylsiloxane), [MeSiHO] . 

Institute of Science end Technology This biennial review covers 1969 arxl 1970 literature on saturated fluorocarbons, fluorocarbon halides ar>d hydrides, arnf poly-flOro-organic compounds and their spectroscopic properties 307pp 7 00... 

The reactions proceed with an e.e. of about 80% when the enantiopure ligand is used. Similar conditions using poly[oxy(methylsilylene)] (PMHS) as the hydride donor lead to reduction of aryl ketones with up to 98% e.e.188... 

ALKYL, HYDRIDE, AND HYDROXIDE DERIVATIVES OF THE s- AND p-BLOCK ELEMENTS SUPPORTED BY POLY(PYRAZOLYL)BORATO LIGATION MODELS FOR CARBONIC ANHYDRASE, RECEPTORS FOR ANIONS, AND THE STUDY OF CONTROLLED CRYSTALLOGRAPHIC DISORDER... 

IV. Terminal Hydride Derivatives of the s- and p-Block Metals Supported by Poly(pyrazolyl)borato Ligation... 

By analogy with the alkyl derivatives described earlier, poly(pyrazo-lyl)hydroborato ligation may also be utilized to support monomeric terminal hydride derivatives [TpRR ]MHn. However, at present, the chemistry of such complexes is effectively restricted to that of four-coordinate derivatives of the type [TpBut]MH. 

Reduction of Poly(2-cyano-l,3-phenylene arylene ether), 20 Twenty-five mL of a 1.0 M solution of lithium aluminum hydride (LAH) in THF was cooled to 0° C before adding a solution of 1.64 g (5.0 meg) of 20 in 120 mL of THF. The resultant slurry was stirred for 24 h at 0° C, refluxed for 1 h, recooled to 5° C, and the excess LAH decomposed with 2 mL of water. The volume of the solution was reduced to 25 mL before pouring the mixture into 500 mL of 5% HC1 to dissociate the amine aluminum salt complex and precipitate the polymer. The polymer was recovered by filtration, reslurried in 20 mL of water and the pH adjusted to 9.0 with NaOH. After recovery of the neutralized polymer was recovered, it was dried in vacuo redissolved in CHC13, and reprecipitated using water as the nonsolvent. Final drying in vacuo for 24 h at 35° C left 1.2 g (72.3%) of poly[oxy-l,4-phenylene-(l-methylethylidene)-l, 4 -phenylene-oxy-(2"-aminomethyl)-l",3"-phenylene], 21, [n] (CHCI3) 0.3 dl/g. 

Tri-rirbutyltin Hydride Reduction of Poly (vinyl chloride)... 

Starnes and Bovey (1) pioneered the method of I3C NMR analysis of reduced poly(vinyl chloride) (PVC) to study the microstructure of PVC. Tri-n-butyltin hydride ((n-Bu)3SnH) was found to completely dechlorinate PVC resulting in polyethylene (PE) whose microstructure (branching, end-groups, etc.) could be sensitively studied by 13C NMR. 

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