Fe , structure

Resonance Raman studies of the recombinant proteins showed vibrational bands at the 200-430 cm region characteristic of iron-sulfur clusters (124). Most interestingly, on Fe and O isotope sensitive band was detected at 801 cm which could be attributed to either a Fe(IV)=0 species or a monobridged Fe-O-Fe structure. This observation, together with Mossbauer analysis, which indicated a mixed N, 0, and S ligand environment for cluster 2, suggests a Fe-O-Fe or Fe=0 unit as part of the structure for cluster 2. 

Dewhirst FE. Structure/activity relationship for inhibition of prostaglandin cyclooxygenase by phenolic compounds. Prostaglandins 1980 20 209-222. 

Nicolet Y, Piras C, Legrand P, et al. 1999. The structure of Desulfovibrio desulfuri-cans Fe-hydrogenase shows unusual coordination to active site Fe. Structure 7 12-23. 

If austenite is cooled slowly toward ambient temperature, the dissolved carbon in excess of 0.022 weight % comes out of solid solution as cementite, either in continuous layers of FeaC (pearlite) or as layers of separated FeaC grains (bainite). In either case, the iron is soft and grainy, as with cast iron. If, on the other hand, the hot austenite is cooled quickly (i.e., quenched), the 7-Fe structure goes over to the a-Fe form without crystallization of the interstitial carbon as cementite, and we obtain a hard but brittle steel known as martensite in which the C atoms are still randomly distributed through the interstices of a strained a-Fe lattice. Martensite is kinetically stable below 150 °C above this temperature, crystallization of FesC occurs in time. 

Another example of partial degradation of the Fe3(CO)i2 triangle is furnished by its reactions with phosphino-acetylenes which lead to complicated open Fe structures bridged by phosphido ligands and resulting acetylene dimers (79, 311). 

Thus while none of the early formulations of the diiron structure (5, 7) proved to be correct, Seel s 1942 formulation of the structure of [Fe4S3(NO)7] (5), based upon the FeS structure, is remarkably close to the molecular structure found by X-ray analysis (11, 39). 

Figure 2.7 (a) The W3Fe3C structure (cutting steel) The red balls denote iron atoms (b) D-surface separating the Fe structure (red stellar tetrangulae) and the VV3C structure (yellow octahedra). 

Single-crystal polarized X-ray absorption spectroscopy is not consistent with a linear Fe—Mo—Fe structure and Mo=0 was only observed in oxygen-inactivated protein. Only very minor changes oc-... 

Martensitic chromium steels (AISI 400 series) contain no (or very little) nickel, and the chromium content is typically about 12%. These steels can undergo the a-Fe/7-Fe transition at about 1050 °C and so can be heat-treated for improved mechanical properties, much as can ordinary carbon steels. Since they have the a-Fe structure at ambient temperatures, they are ferromagnetic in ordinary service. Examples are type 410 (11.5-13.5% Cr), which is used for turbine blades, and type 416 (12-14% Cr with minor amounts of Se, Mo or Zr), which has good machinability. 

There are four main classes of stainless steel (austenitic, ferritic, ferritic-austenitic (duplex) and martensitic), and within these, a variety of different grades. The names ferritic and austenitic follow from their structures ferrite (P-Fe) and austenite (y-Fe) structures hosting the alloying elements. The presence of Cr promotes the formation of the ferrite structure, while the austenite structure forms when Ni is introduced. While ferritic and martensitic stainless steels are magnetic, austenitic stainless steel is non-magnetic. Further additives to some stainless steels are molybdenum (which improves corrosion resistance) and nitrogen (which adds strength and improves corrosion resistance). 

Cha] Magnetic properties measurements, magnetostriction measurements, XRD Co based alloys with 4 to 15 mass% Cu and 9 to 13 mass% Fe, structural and magnetic properties of electrodeposited alloys... 

Table 9. Fe Structure in Aluminophosphates and Test of Catalytic Activity... 

Structiire Fe structure and redox behavior Characterization method Comments Catalytically active in Reference... 

The similar coordination number and first peak position in the Invar samples suggests that the Ni atoms effectively substitute into the pure Fe structure. The uncertainty on the first peak positions and coordination numbers is 0.02 and 0.6 respectively. The relatively large error in the coordination number occurs in part due to the poorly defined first minimum in each G(r)... 

---