Talk:Phosphorus trifluoride

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Overall nice job, but highly technical for the general Wikipedia reader, more so than PCl₃ and PBr₃. Some observations:

In the introductory paragraph:

• "It is highly toxic and it reacts slowly with water."

In the "Chemical properties" section:

• "Phosphorus trifluoride hydrolyses fairly rapidly in water, and very rapidly under under alkaline conditions, but PF3 is less reactive in this regard than phosphorus trichloride."

In the "Precautions" section:

• "It also reacts slowly with water to form the highly toxic and corrosive hydrofluoric acid,"

In the Table:

• "Solubility ..... Water: slow hydrolysis:

Maybe a bit of a contradiction on the reaction speed here?

Well spotted! I recall the problem when writing this, the different sources used different comparative terms depending on the context, I must have got a bit confused by it all.

Also, I went with 2 out of 3 and changed the F-P-F bond angle from 104° to 96.3° in "Physical properties". See values in picture and table.

Thanks, I agree.

PF₃ seems to have a remarkably low boiling point compared to PCl₃. Also. I noticed the (single covalent) bond strength of 119.4 kcal/mole seems rather strong compared with many single covalent bonds in organic compounds. Bond strengths weren't given for PCl₃ or PBr₃. Also, I noticed a dipole moment of 0.8 D was given for PCl₃, but no dipole moment was given for PF₃ or PBr₃. H Padleckas 17:15, 7 May 2005 (UTC)

Low BP may be due to strong electronegativity of F, this is not unusual (BF3, SiF4, CF4, PF5 are all gases, yet the chloro equivalents are not). The bond strength is not something I'd thought to include, but I've usually done ionic compounds. It seemed more important here precisely because it is strong, rather like Si-F, F forms some very strong bonds generally- though I may go back & add in bond strengths for the others, especially if we start the idea of supplement pages. As for the dipole moment, I only have data for PCl3. Thanks for the review, and also to Physchim62, Walkerma 13:39, 9 May 2005 (UTC)

The reaction of PF₃ with water is slow; it is the Chemical properties section which needs copy-editing. I have a slight gripe with the Preparation section: transhalogenation of phosphorus halides is certainly possible, but in this case it is particularly messy. My memory of the preferred preparation is the reaction of phosphorus pentafluoride with elemental phosphorus, but I would rather someone check this before posting it on the article. In general, hydrogen fluoride and calcium fluoride are poor fluorinating agents, and I doubt that they would work well in this case. Sorry I can't be more precise, but my nearest university libraries are in Lens and Lille so I cannot immediately find sources for this info. Physchim62 19:01, 10 May 2005 (UTC)

As for the dipole moment, it is notably small and so worth a mention if anyone can find a figure for it. Nitrogen trifluoride is even more remarkable from this point of view: the bond dipoles and the dipole due to the lone pair cancel each other out almost exactly. Physchim62 19:09, 10 May 2005 (UTC)

I haven't personally worked with it, only with PF5, but the zinc fluoride reference is from Inorganic Syntheses (reference 7), so it should be good. The preps come from the Toy book (ref. 5), though Greenwood & Earnshaw only refer to ZnF2 or AsF3, and I seem to recall that the Merck Index listed the same things. I left all four in because at present we don't have pages for AsF3 or ZnF2, but I made sure I used the IS method in the equation. Toy also mentions benzoyl fluoride, and he says "reaction of red phosphorus with liquid HF in a closed system has also been reported." That last phrase implies "if you choose to believe that," and suggests that everyone uses the PCl3 method. I have not seen P + PF5 anywhere, despite the fact that PCl3 and PBr3 are made by that approach, but I can't rule it out. Walkerma 19:32, 10 May 2005 (UTC)

• I have now checked as far as I can, including thermodynamic data. I withdraw my comment on the preparation of PF₃. Apologies to all. Physchim62 18:54, 18 May 2005 (UTC)