Boron metals

H. Schuerch, Compressive Strength of Boron-Metal Composites, NASA CR-202, April 1965. 

The first boron-metal a bond to be discovered is in (Me2N>2BMn(CO)5... 

The B atoms in the mono- and diaminoboranes (R2N)2BR and R2NBR2 show only moderate functions. Therefore, boron-metal interactions are relatively weak. 

The intermediate (MeOBCjH jlFefCOIj shows no boron-metal bonding. The borinato sandwich is formed if boradiene tricarbonyliron is heated to 165°C for 12 h. 

The early sixties saw a broad and intense interest in the making of the heretofore unknown molecular compounds with a boron-metal bond (8). In 1963, the first compounds with boron-metal [Pg.200]

In 1970, the synthesis of the orange-red sandwich cation 1 from cobaltocene and PhBCl2 (1) marked a further starting point in the chemistry of boron metal compounds. The presence of a planar benzenoid C5H5B ligand moiety in 1 was deduced from XH and UB NMR data (1). This was made ironclad by two X-ray structure determinations which revealed typical centrosymmetric sandwich structures for the 19-e complexes Co(C5H5BOMe)2 (6) (21,22) and Co(C5H5BMe)2 (7) (22) as shown in Fig. 1. 

Table 14 Complexes with a Boron—Metal Bond...

Type of boron ligand Metal complex or complex unit partner Substituents at the boron Metal- boron ratio Ref. 

The intermediacy of B—H— -metal linkages in the formation of direct boron-metal a bonds is well illustrated by studies in carbaboranetungsten-platinum chemistry. The reaction between the salts [PtH(Me2CO)(PEt3)2]-... 

Other examples of compounds with exopolyhedral boron-metal a bonds mentioned in Section VI. 

As an aside, Jacobson and DeJonghe have reported that simply heating Nicalon or Tyranno fibers at temperatures of ca 1600°C with sources of boron (e.g. boron metal, TiB2 etc.) leads to sufficient incorporation of boron into the fibers such that they densify and stable, nearly phase pure, SiC fibers are obtained. No data are provided about fiber composition118. 

A second class of compounds having boron metal a-bonds is exemplified by species such as (C6H3)2BMn(CO)4P(C6H5)3 (31). 

Elemental boron is a refractory material that is usually isolated either as a shiny black crystalline solid or a softer, browner, more impure amorphous solid. Reduction of readily available boron compounds containing boron oxygen bonds to elemental boron is energy intensive and costly. This has limited the extent of conunercial use of this material. Many related refractory boron compounds have been prepared and characterized including metal borides, boron carbides, boron nitrides, and various boron metal alloys. These refractory materials and elemental boron are also discussed in some detail in the article Borides Solid-state Chemistry. Other general references are available on elemental boron and other refractory boron compounds. " ... 

Boron Boron, metallic EINECS 231-151-2 HSDB 4482. Nonmetallic element. Used in special-purpose alloys cementation of iron neutron absorber in reactor controls oxygen scavenger for copper and other metals fibers and filaments in composites semiconductors rocket propellant mixtures, mp = 2200" insoluble in H2O. Atomergic Chemetals Noah Chem. 

Presumably these processes also involve transient formation of boron-metal single bonds. Recently it was reported that oxidative addition of (1- or 2-)BrB5H8 to IrCl(CO) (PMe3)2 formed cis-dihromo-trans-his-(trimethylphosphine) (2-pentaboranyl) carbonyliridium (III) (29). 

Fibrous reinforcement in popular usage is almost synonymous with fibreglass, although other fibrous materials (carbon, boron, metals, aramid polymers) are also used. Glass fiber is supplied as mats of randomly oriented microfibrils, as woven cloth, and as continuous or discontinuous filaments. Hand lay-up is a versatile method employed in the construction of large structures such as tanks, pools, and boat hulls. 

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