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Davidoffski Mgr and Mgr magnezocen

Shortly after the discovery of ferrocene in the early 50 different researchers began looking for other metal sandwich complexes. I just flew kobaltoceny, wanadoceny etc. Interestingly, we found that this type of connection can also create main group elements, including magnesium.

Magnezocen (actually bis (cyclopentadienyl) magnesium ) was synthesized for the first time independently by Cotton and Wilkinson and Fischer and Hafner in 1954 year. The diagram below shows two possible routes of synthesis

MGCP ₂ is a crystalline , piroforycznym a solid white color. It is soluble in polar solvents and nonpolar. It is very sensitive to moisture, is rapidly hydrolysed to Mg (OH) ₂ and cyclopentadiene . Case type bonds in the molecule magnezocenu was (and still is actually) the issue of debate. The fact that MGCP ₂ shows structural similarity to the ferrocene, and has no dipole moment does not show clearly the nature of covalent bonds. If we assume a purely ionic nature of the interactions, sandwich structure magnezocenu would be beneficial in view of electrostatic interactions. The high polarity bonds in magnezocenie also shows some experimental data, such as electrical conductivity in solutions of liquid ammonia and tetrahydrofuran, rapid hydrolysis and the similarity of chemical shift in the spectrum ¹³ C-NMR shifts of the metal cyklopentadienylkach a group which, as is known, are compounds with the ionic structure [ LiCp d = 103.6 ppm, stoned d = 103.4 ppm, MGCP ₂ d = 108.0 ppm , while for covalent FeCp ₂ d = 68.2 ppm]. On the other hand, the data resulting from studies of solutions of Cp ₂ Mg nonpolar solvents using spectroscopic ²⁵ Mg-NMR (Small signal width at half maximum for the spectrum performed in toluene at room temperature, d = -85.4 ppm In _½ = 150 Hz) indicate the nature of covalent bonds.

Magnezocen is used in the synthesis of other sandwich complexes and in the process of p-doping of GaN and AlInGaP (Aluminum indium gallium phosphide).

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Davidoffski and salts with an alter ego. Part 2 - chloride, cobalt (II). Mgr

hydrochloric After the first part of the cycle, consisting of iron salts, it's time for the next group of salt. Sponsor of today's post is COCl ₂ ;)

At the beginning of the second semester of the academic year 2009/2010 it was my longed-for moment - The first classes for students! These classes were exercises in the laboratory of inorganic chemistry, in my case, conducted for students with specialization biological chemistry. The question of the conduct of unconventional mgra Davidoffskiego, specific questions and concerns will be built even under consideration here on the blog, so I leave these matters for later;) The important thing now is the fact that one of the exercises that I was able to conduct related to cobalt compounds. Preparing a comprehensive classes discovered many interesting news on the cobalt salt alone (not to mention nothing of other compounds, of which "struggled" with a smile on my students;). Thus the merits;)

chose cobalt chloride (II), because this compound probably has the greatest number of impressions;) Anhydrous COCl ₂ obtained in direct reaction of metallic cobalt with chlorine. This is a solid blue color, the host structure CdCl ₂ . COCl ₂ easily absorbs moisture from the air, forming a pale pink hydrates.

trans - [COCl 2 (H 2 O) 4 ]

Crystalline COCl ₂ × 6H ₂ About includes units trans - [COCl ₂ (H ₂ O) ₄ ] which are connected with other water molecules through a network of hydrogen bonds. The COCl ₂ × 4H ₂ About is composed of molecules connected by hydrogen bonds cis - [COCl ₂ (H ₂ O) ₄ ] . 

cis - [COCl 2 (H 2 O) 4 ]

last in the queue hydrate COCl ₂ × 2H ₂ About have different structure - it consists of interconnected walls oktaedrów:

real fun chloride, cobalt (II) gets going in earnest in aqueous solution. Key individuals are [Co (H ₂ O) ₆ ] ^{2 +} , [COCl (H ₂ O) ₅ ] ⁺ and [COCl ₄ ] ^{2 -} , and accompany them in smaller quantities [COCl ₂ (H ₂ O) ₄ ] and [COCl ₃ (H ₂ O) ₂ ] ^- .

[COCl ₄ ] ^{2 -} is an anion complex of blue color. Arises when the solution containing akwajon cobalt (II) is added concentrated hydrochloric acid. Interestingly, you can also occasionally get this ion, by heating the solution COCl ₂ is observed when a very nice color change from pink to blue;) In the COCl ₂ also worth to note that this salt forms adducts with tetrahedral structure, the type of COCl ₂ × 2L , with neutral donors. Interestingly, these donors in the presence of these adducts are reduced by creating derivatives of general formula COCl × L ₃ , eg COCl (PR ₃ ) ₃ . These compounds can be further modified to allow to obtain the whole range of other combinations of cobalt - both inorganic and organometallic compounds. The reaction with ammonia [Co (H ₂ O) ₆ ] ^{2 +} gives aminakompleks [Co (NH ₃ ) ₆ ] ^{2 +} that quite easily oxidized to [Co (NH ₃ ) ₆ ] ^{3 +} .

Converse Double Eyelet

Davidoffski and salts with an alter ego. Part 1 - salts of iron (III).

There were times long ago, when everything was simpler. In middle school (formerly the primary school) and taught at the high school construction chemicals in a very simplified way to explain the basic rights-friendly chemistry. In college course material is greatly expanded, but even then he discovers the students all the really great mysteries ...

secrets will be uncovered today seemingly trivial and obvious associations which are salts. Sole or middle school students and high school nightmare: DW during those less than six years, during which I give private lessons, have not met with more prohibitive for young people theme: P Today, however, will not virtually nothing about the methods of obtaining salt, today I will tell about what salts are in fact ... both in the solid state and in aqueous solutions.

Take a simple example at the beginning - FeCl ₃ , or ferric chloride (III). Anhydrous salt solid-state structure of the iodide of bismuth (III) BII ₃ and forms hygroscopic crystals, dark green or black. This salt dissolved in water gives a strongly acidic solutions. So let's look into this solution. As you know, the metal ions in water are not simple cations, but the so-called. akwajonami. In the case of iron (III) that is akwajonem heksaakważelaza cation (III) [Fe (H ₂ O) ₆ ] ^{3 +} . In aqueous solutions, such akwajony may behave as Bronsted acids by placing a proton H ⁺ . This is also true in the case [Fe (H ₂ O) ₆ ] ^{3 +} , as illustrated following equations:

[Fe (H ₂ O) ₆ ] ^{3 +} + H ₂ O -> [Fe (H ₂ O) ₅ (OH)] ^{2 +} + [H ₃ O] ⁺

[Fe(H ₂ O) ₅ (OH)] ²⁺ + H ₂ O -> [Fe (H ₂ O) ₄ (OH) ₂ ] + [ H 3 O] ⁺

This process also affects the color of the solution. [Fe (H ₂ O) ₆ ] ^{3 +} color is purple, but anyone who has seen salt solutions of iron (III) know that they are color brązowożółtej. For this situation arising due to hydrolysis correspond hydrokso complexes of iron (III). Now, back to the ferric chloride (III). The solution Water can be crystallized hydrate FeCl ₃ × 6H ₂ About , orange-brown color. Properly stored, however, the model of the hydrate is trans - [FeCl ₂ (H ₂ O) ₄ ] Cl × 2H ₂ O which contains The structure of ion on the construction depicted in the figure below:

But, but ... It's not all!;) The effect of hydrolysis [Fe (H ₂ O) ₆ ] ^{3 +} can also create a bridge structure, including [(H ₂ O) ₅ feof (H ₂ O) ₅ ] ^{4 +} :

this cation is already quite an uncle;) bridge Fe-O-Fe is linear, as seen above, which indicates the presence of binding (dp) π formed by the overlap of d orbitals of iron and p orbitals of oxygen. The structure of the cation determined by X-ray structural salt crystallized [(H ₂ O) ₅ Fe (μ-O) (H ₂ O) ₅ ] [ClO ₄ ] ₄ × (18-crown-6) ₂ × 2H ₂ About . In this system, crown ether is linked by hydrogen bonds and coordinated with the iron atoms of water molecules:

Crown ether 18-crown-6 has the following structure:

interesting case is Fei ₃ . This salt decomposes very easily:

2 Fei ₃ -> 2 Fei ₂ + I ₂

this compound can not be obtained by reaction of Fe ^{3 +} of iodides, iron (III) is reduced to Fe ^{2 +} and releases the free iodine. However, you can address the problem and isolate Fei ₃ under neutral conditions (eg, argon) in the following reaction:

2 Fe (CO) ₄ I ₂ + I ₂ -> 2 Fei ₃ + 8 CO

No! As it can not, as you can?;) Let's look at yet another Solom iron (III))

Anhydrous Fe (ClO ₄ ) ₃ is solid yellow. Commercially available in hydrate form of a rather different water content, and it is in response Fe ₂ About ₃ × H ₂ About with aqueous HClO ₄ . Depending on the degree of contamination by chlorides may be pale mauve (less than 0.005% of chloride content), or yellow.

sulphate (VI) iron (III) Fe ₂ (SO ₄ ) ₃ create white or beige crystals, is available as a hydrate Fe ₂ (SO ₄ ) ₃ × 5H2O . Nitrate (V), iron (III), in turn, creates a colorless or pale violet crystals of hydrate of formula Fe (NO ₃ ) ₃ × 9H ₂ About , whose record looks correct, however, follows: [Fe (H ₂ O) ₆ ] [NO ₃ ] ₃ × 3H ₂ About . Is obtained by the reaction of iron oxides with concentrated HNO ₃ . However, purple hexahydrate Fe (NO ₃ ) ₃ × 6H ₂ About (and correctly: [Fe (H ₂ O) ₆ ] [NO ₃ ] ₃ ) is obtained by reacting Fe ₂ About ₃ × H ₂ About of HNO ₃ .

enough for today! Coming soon will be a continuation of the story of salt;)