Tetrahydroborates structure

Hydrido derivatives, of high-nuclearity carbonyl clusters, structure, 30 168-172 Hydridogallium iis(tetrahydroborate), 41 189-192... 

The physical and chemical properties of the tetrahydroborates show more contrasts than the salts of nearly any other anion. The alkali metal salts are the most stable. In dry air, NaBH4 is stable at 300°C and in vacuo to 400°C with only partial decomposition. In contrast, several tetrahydroborates, including the titanium, thallium, gallium, copper, and silver salts, are unstable at or slightly above ambient temperatures. The chemical and physical properties of the tetrahydroborates are closely related to molecular structure. Sodium tetrahydroborate, which is typical of the alkali metal tetrahydroborates except for the lithium salt, has a face-centered cubic (fee) crystal lattice which is essentially ionic and contains the tetrahedral [BHJ- anion. The tetrahydroborates of the polyvalent metals are in many cases the most volatile derivatives of these metals known. Aluminum tris(tetrahydroborate)... 

A series of diheteronuclear complexes was isolated (3.218) on the basis of metal bis-phospholyldichlorides (tetrahydroborates) [486], They are bidentate P-donor chelating ligands and form metal-cyclic structures. The chelates of the type 772 [486] are typical examples of such compounds ... 

Fig. 13. Molecular structure of [Me3SiOAl(BH4)2]2, dimeric trimethylsilyloxy-aluminum-bis(tetrahydroborate) [33]...

A metathesis reaction is a convenient route to lanthanide tetrahydroaluminate and lanthanide tetrahydroborate complexes. Using tetrahydroaluminate complexes as the hydride source, a number of structurally characterized lanthanide tetrahydroaluminate complexes are prepared via metathesis reactions in the presence of an excess of a Lewis base (Equation 8.24) [79]. Metathesis reaction of organolanthanide chlorides with alkali metal tetrahydroborate generates the corresponding lanthanide tetrahydroborate. The same reaction with sodium hydride in THE is reported to afford a lanthanide hydride however, no molecular structure for the hydride has been presented up till now. 

With this repertoire of bonding possibilities at our disposal, we car construct the molecular structures of various boron-hydrogen compounds, both neutral species and anions. The simplest is the tetrahydroborate 26 or borohydride ion, BH. Although borane is unstable with respect to dimerization, the addition of a Lewis base, H . satisfies the fourth valency of boron and provides a stable entity. Other Lewis bases can coordinate as well. 

The ability of phosphines to act as both a metal oxidation states and as a 7r acceptor to relieve electron density from lower metal oxidation states explains, in part, the observation that diphosphines stabilize the +3, +1, and 0 oxidation states at the expense of the +2 oxidation state.870 Vanadium(II) diphosphine halides, [V(dmpe)2X2] (dmpe = dimethyl-dimethylphosphinoethane, X = Br or I), were prepared as side products in the synthesis of [XV(CO)2(dmpe)2].885 The structurally characterized diphosphino V11 tetrahydroborate complex, tra .s-[V(BH4)2(dmpe)2], (223) was synthesized via the reduction of similar vanadium(III) precursors.832 The reaction of a vanadium(II) chloride salt with dmpe afforded the tra s-[VCl2(dmpe)2] complex which can be alkylated with MeLi or MgMe2 to afford the organometallic trans-[V(Me)2(dm pcVJ compound, which in turn reacts with thiocyanate to form tnms -[V(NCS)2(dmpe)2].8 87 Acetonitrile or propionitrile readily displace the chlorides from trans- WCl2(dmpe)2] to form // tf/ ,v-[V( NCR)2(dmpc)2][BI>h4]2 (R = Me or Et) the acetonitrile derivative reacts with HCPh(S02CF3)2 in acetonitrile solvent to yield the hexaacetonitrile species [V(NCMe)6]2+.887... 

The reaction of (C9H7)2LnCl(THF) with NaH in THF generates the dimeric bis(indenyl)lanthanide hydrides [(C9H7)2Ln(/r-H)]2 4THF-NaCl.695 The stereoselective synthesis and structural characterization of raf-planar chiral bis(2-methoxyethylindenyl)lanthanum and yttrium tetrahydroborate complexes has been achieved. The complexes... 

Simple complex ions such as ammonium 5) ancj tetrahydroborate can be drawn in a similar way the valence structures shown are essentially identical to those for CH4 as the total... 

Table 15.1 Density of tetrahydroborate, for crystal structures reported elsewhere... 

Table 15.5 Crystal structure of alkaline-earth tetrahydroborate M(BH4)2 (M = Ba, Mg and Ca)...

Keywords Tetrahydroborate Complexes Coordination Modes Structural Trends Bonding Analysis Hydrogen Exchange Dynamics... 

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