freakJoe

I have problem with those tasks, i was reading about rule, but still have no idea what to do... 1) FeTiO3 (mineral Ilmenite) possesses the corundum structure (remember our discussion in the class) – an hcp array of oxides with cations filling 2/3 of octahedral holes. Use the bond valence rules (Second Pauling’s Rule) to decide which oxidation states are present: Fe(II) Ti(IV) or Fe(III) Ti(III). Bond Distances (dexp, Å) Tabulated reference values Constants FeO = 3×2.07 and 3×2.20 R0(FeO) = 1.795 Å b = 0.30 TiO = 3×1.88 and 3×2.09 R0(TiO) = 1.815 Å b = 0.37 Check for oxygen valence (what is the coordination number of O?): each oxygen is bound to Fe and Ti with both bond distances.) 2) CaWO4 has the scheelite structure where the W6+ ions are tetrahedrally coordinated. Use the bond valence rules (Second Pauling’s Rule) to decide if the WO4 tetrahedra share corners, i.e. oxygens are bridging, or the WO4 tetrahedra are isolated, i.e. oxygens are terminal. Show your bond strength calculation.

What is the solubility of silver salt of the formula RCOOAg (RCOO=phenylbutyrate, DMF, MeOH, water?)

hi! i have some strange by-product, intermediate, or something... i prepared inorganic complex, and it is contaminated ith something (have problems with purification), when i measure platinum NMR, i can observe signal of my product (which should be yellow), but it is yellowish and white (or white-beige). How could i determine, what is inside, beside my product? could Electrospray measurement help me (ESI-MS)? as far as i know, it can tell you if you have some desired compound structure, but what if it is a mixture? is there any technique to analise what is my product?

Hello! i will use NMR spectroscopy to determine host-guest binding, and i would like to kindly ask you, what technique is the best to perform NMR titrations!! I probably should prepare solution of guest, and add in portions cavitand into it (also as solution, in the same solvent, e.g. deuterated water)... is it reasonable to prepare mixture of guest with cavitand every time again? like preparation of host-guest, so i: take some part of solution nr 1 (guest solution, prepared for 10 trials for different ration, which volume is constant), add some part of solution nr 2 (cavitand solution, prepared for several trials, which volume changes - 0.5 eq, 1 eq, 1.5 eq with respect to guest), at the end add volume of deuterated solvent to have constant volume of mixture in NMR tube. Would it be right?

Hello! i will use NMR spectroscopy to determine host-guest binding, and i would like to kindly ask you, what technique is the best to perform NMR titrations!! I probably should prepare solution of guest, and add in portions cavitand into it (also as solution, in the same solvent, e.g. deuterated water)... is it reasonable to prepare mixture of guest with cavitand every time again? like preparation of host-guest, so i: take some part of solution nr 1 (guest solution, prepared for 10 trials for different ration, which volume is constant), add some part of solution nr 2 (cavitand solution, prepared for several trials, which volume changes - 0.5 eq, 1 eq, 1.5 eq with respect to guest), at the end add volume of deuterated solvent to have constant volume of mixture in NMR tube. Would it be right?

when we have for example KPtCl3(NH3) complex, the Pt-N bond is probably more short bond that Pt-Cl... what can i say about them? should it influence the bond which is in trans position to NH3 substutuent? shouldnt it be affected by it, e.g. become weaker? what about orbitals? some polarization? when you have KPtCl3(NH3) molecule, and you add next 1 eq of NH3 to it, it will substute the chloride which is in cis position to NH3 which is aready in molecule, right? becaus NH3 has weaker trans effect than Cl- so it cant put in trans position to itself.

no solvent and water?

It is a part of theoretical investigation... computational chemistry... and i would like to compare calculation results with some theories. I am not sure if i am correct, but i was thinking about the nature of the group attached to NH2. Is it possible, that thanks to -CH3 substituent, which push electrones towards N atom, it makes the molecule more basic? It would tend to accept extra proton more then for example NH2OH, where -OH group withdraw the electrons...?

Which of these molecules is the most basic? NH3, NH2CH3, NH2NH2 or NH2OH?

what is the relationship between the geometry or energy difference between orbitals and chemical shift? Like, for octahedral Pt(IV) is +800, for square planar(II) -2000...

So for water is the same i guess... When i want to substitute chloride ligands (e.g. reaction of chloride with some silver salt), it is better to use iodide instead of chloride, because of good separation (reaction is in water, the product is soluble in water) and iodide has a "high affinity" to silver?

It is not soluble in DMF, right? neither AgCl

phenylacetic acid

how to prepare it in a very simple way, starting from phenyl acid? i would like to avoid hard to remove contaminations and use only cheap chemicals... is it good idea to convert acid into salt, and react this salt with acid?

Hi, how it is with fern at home? my mum already had lot of them but they are usually dying after about half year... i had one as well, and no matter if i water it a lot, or very rarely, after some time its leaves are getting brown and it is dry... even if ground is wet... i tried to optimize conditions, but why is that? how to water it and keep it in a good condition for a long time? Thanks!

Hi, i would like to know more about practical NMR spectroscopy... Please correct me in places where i am wrong... People who are measuring their samples in spectrometers use Bruker Topspin software, they put sample into the magnet, when it is inside, they use command LOCK for locking the magnetic field for the current sample (try to make it stable and homogenous?), then TUNE for "tuning and matching for ATM probeheads" - what does it mean? Then, SHIMMING (again about homogenity of magnetic field, something about gradients?), they set parameters like o1p (expected position of the signal), sw spectral width - from which nr to which nr of frequency we can observe the window, ns number of scans - what does i means in details? then, GAIN adjusting receiver gain "performs acquisition with varying receiver gain RG and finally sets this just below the value where no digitizer overflow occurs" - what does it mean? what is acquisition? and GO starts acquisition. When measurement is finished, we use Furier Transform to transform the spectrum from the time domain to frequency domain...

I tried to prepare it, but: 1) it was unsuccesful, or 2) this small portion was decomposed before i measured IR. Is there any test to check, if it is isocyanate? some reaction in which i could obtain: 1) some colorful substance what could confirm it is the right compound, or 2) just something i could confirm its structure by e.g.NMR spectroscopy. I mean if some characteristic reaction with something will be succesful, it means that was isocyanate. I can´t risk and try it in my reaction, because i work with quite expensive complexes... By the way, why oxalyl chloride is worse? Sorry for my english, and if my text is a bit chaotic, but i work and learn for 10-13h every day and i am exhausted zzzz..

Yes carbamates... What ways do you mean? my starting material is oxidized complex with one/two -OH groups... that is why i use isocyanates. Thank you very much for help!

Thank you so much! You are so helpful! By the way, about Boc-... I have some idea, but i am not sure, if i can prepare isocyanate from this compound: http://www.sigmaaldrich.com/catalog/search?term=4-%28Boc-aminomethyl%29benzoic+acid&interface=All&N=0&mode=match%20partialmax〈=en&region=CZ&focus=product Is Boc- protecting group stable enough to survive this reactions? I would have to remove Boc- group later, after reaction of isocyanate with the the compound that contain hydroxyl group), as the final compound is much more stable...

Thank you. I have found some publication, but there is no real procedure, they just mentioned that isocyanate was prepared in reaction of amine with oxalyl chloride... nothing more, and in cited literature i can´t find the real procedure as well... Once i prepared some isocyanate starting from acid (so several steps), and measurement of IR was succesful... so, i hope, this time it will be OK as well... Then I plan to use it immediately in next reaction step. I am not experienced in such a type of syntheses, but i was probably lucky By the way, they carry out the 1 step of the reaction (triphosgene in THF + DIPEA) in 0o C, so the reaction mixture before addition of amine should be cool, so i guess ït is very exothermic? After all amine was added, i can remove ice-water bath? And i should probably carry it out in an inert atmosphere of argon, and be careful and avoid the moisture, right? I am not sure about the mechanism of the reaction... What is the role of DIPEA? does it has to remove some chlorides?

I have found patent (WO 2014/100417), in which they descibe preparation of isocyanate from amine. They use amine, triphosgene, THF, N,N-diisopropylethylamine (DIPEA). Is it possible to use DMAP or pyridine instead of DIPEA and oxalyl chloride instead of triphosgene? i am not sure about the mechanism of this reaction... what is more, on the reaction scheme they write piridine (no DIPEA) and now i am not sure if they made mistake... i havent found the same reaction with different substitutes http://worldwide.espacenet.com/publicationDetails/originalDocument?CC=WO&NR=2014100417A1&KC=A1&FT=D&ND=&date=20140626&DB=&&locale=en_EP

Hi, i was trying to prepare it, but it seems to me it is contaminated with salt probably... at the final step, i evaporate it completely, as they recommend... when i was trying not to evaporate it completely, the purity was better but the yield was extremely low after crystallization... did anyone of you prepare pure carboplatin? i followed this procedure (Inorganica Chimica Acta 359, 2006, p. 4095–4104): 1) Ag2R(COO)2: Two millimoles of aqueous NaOH are added to 1 mmol of the dicarboxylic acid dissolved in a small quantity of water. Two millimoles of AgNO3 are then added to the sodium dicarboxylate solution in the dark. A white precipitate forms immediately. The mixture is stirred for 15–30 min and the silver compound is filtered, washed with water, dried in air and finally in a dessicator. The yields are between 60% and 80%. 2) Pt(amine)2R(COO)2: The two compounds cis-Pt(amine)2I2 and Ag2R(COO)2 were mixed together in water in a 1:1 proportion. The mixture is stirred in the dark during 2–3 days until the formation of AgI is complete. The yellow precipitate is filtered out and the filtrate is evaporated to dryness. Thanks in advance.