Hydride compounds characterization

Tetrahydroborates. The tetrahydroboranes constitute the most commercially important group of boron hydride compounds. Tetrahydroborates of most of the metals have been characterized and their preparations have been reviewed (46). The important commercial tetrahydroborates are those of the alkah metals. Some properties are given ia Table 4. 

The interstitial hydride [Lig(H) N(2-pyridyl)Ph 6]+ [Li(Me2AFBu2)2] has been reported. Similar hydride compound [Li7(H) N(2-pyridyl)Ph ]6 has also been obtained by further treatment of the above reaction mixture with THF. Recently, main-group polyhedral clusters with the Lig(H) moieties has been synthesized by the reaction of a bicyclic l,3,4,6,7,8-hexahydro-2//-pyrimida[l,2-a]pyridimine (hpp) in tandem with ZnMe2 and BnLi. The product is an ion-separated compound [Lig(H)(hpp)6]+ [Zn Bu3] , which has been stmcturally characterized by X-ray crystallography. It has shown that the hydride is enclosed by an unusual (Li+)g cubic cage whose six faces are straddled by the six pyridylamide moieties. ... 

Although there exists a series of monoalkyl cadmium compounds of the type [RCdX] , such compounds are not as extensive as the zinc analogs. For example, alkylcadmium hydride compounds are unknown. Furthermore, the [RCdX] compounds that have been isolated are often not as well characterized as their zinc analogs. 

Monocyclopentadienyltitanium phosphine complexes have also been prepared and reviewed previously. The formally divalent titanium precursor, (r/s-CsI Is)Ti(dmpebCl, serves as a synthon for the corresponding methyl and hydride compounds, ( 5-CsI Is)Ti(dmpe)2k (R = Me, H), which are diamagnetic and crystallographically characterized.57 Addition of ethylene to these compounds results in formation of 1-butene, 3-methyl-l-pentene, and... 

Compounds ReH(PPh3)2(acac)X2 (X = Cl, Br, I) are apparently the first isolated and stable paramagnetic hydride compounds ever reported [56], They were obtained by oxidation of ReH2(PPh3)3(acac), see Scheme 4. Besides elemental analyses, they have been characterized by magnetic susceptibility and IR spectroscopy. In addition, further oxidation or protonation reactions leas to the liberation of H2. 

Diethyl glutaconate and two moles of A -benzylidenemethylamine (XII-95, R = CH3) or benzylideneaniline (XII-9S, R = CgHs) in xylene condense to give compounds characterized as l-substituted-3-benzylidene-S-carbethoxy-2-oxo-6-phenyl-A -piperidenes (interpretation of NMR), which form l-substituted-3-benzyl-5-carboxy-6-phenyl-2-pyridones after heating in methanolic potassium hydroxide. The carboxypyridones have been decarboxylated to Xn-96. Q -Cyano-j3-methylcinnamide and ethyl formate are cyclized in the presence of sodium hydride to 3-cyano4-phenyl-2-pyridone (XII-97). ... 

The early 80 s saw the beginning of the preparation and characterization of rare earth organo hydride compounds (Schumann and Genthe 1981, Evans et al. 1982b) by hydrogenolysis of Cp2Y, Er and Lu alkyl derivatives at atmospheric or high pressure. 

Arsenic Hydrides. Although there are occasionally reports of other arsenic hydrides, eg, AS2H4, AS2H2 (or AsH), and AS4H2, the only weU-characterized binary compound of arsenic and hydrogen is arsine. 

Attempts to classify carbides according to structure or bond type meet the same difficulties as were encountered with hydrides (p. 64) and borides (p. 145) and for the same reasons. The general trends in properties of the three groups of compounds are, however, broadly similar, being most polar (ionic) for the electropositive metals, most covalent (molecular) for the electronegative non-metals and somewhat complex (interstitial) for the elements in the centre of the d block. There are also several elements with poorly characterized, unstable, or non-existent carbides, namely the later transition elements (Groups 11 and 12), the platinum metals, and the post transition-metal elements in Group 13. 

Reductive ring opening of the [i-lactam 10 (X = O), obtained by [2 + 2] cycloaddition of chloro-sulfonyl isocyanate and tetraphenylcyclopentadiene followed by treatment with /7-cresol, with sodium hydride in anhydrous tetrahydrofuran yields 3,5,6,7-tetraphenyl-2//-azepin-2-one (11, X = O).41 Surprisingly, similar treatment of the reduced /Mactam 10 (X = H2) is reported to yield 3,5,6,7-letraphenyl-2//-azepine (11, X = H2), the first monocyclic 277-azepine to be isolated and characterized. Physical data for this compound, however, are inconclusive and attempts to reproduce this synthesis have failed.291... 

Chiang and coworkers synthesized a dimer of compound 26 in which two diiron subunits are linked by two azadithiolate ligands as a model of the active site for the [FeFeJ-hydrogenase [203]. Protonation of 26 afforded the p-hydride complex [26-2H 2H ] via the initially protonated spieces [26-2H ] (Scheme 62). These three complexes were also characterized by the X-ray diffraction analyses. H2-generation was observed by electrochemical reduction of protons catalyzed by 26 in the presence of HBF4 as a proton source. It was experimentally ascertained that [26-2H 2H ] was converted into 26 by four irreversible reduction steps in the absence of HBF4. 

Already partially resolved methyl-1-naphthylphenylgermanium hydride ([otp°° + 10) could also be separated on column A into two fractions characterized by [a] g5 = + 80 and —42 respectively. Partial resolution could even be obtained for the configuration-ally less stable methyl-1 -naphthylphenylgermanium chloride if the elution was carried out with diethyl ether 53), which is much less nucleophilic towards germanium than methanol, which causes the racemization of this compound. 

---