What is the Lewis base in the reaction of oxalate with the mangenese ion to form [Mn(C2O4)3]2-? What is the oxidation state of Mn and the coordination number of the complex?  

(a) Lewis base is C2O42-; Mn oxidation number is +3; coordination number is 3.

(b) Lewis base is C2O42-; Mn oxidination number is +2; coordination number is 6.

(c) Lewis base is Mn2+; Mn oxidation number is +2; coordination number is 3.

(d) Lewis base is Mn4+; Mn oxidation number is +4; coordination number is 6.

Video transcript

All right. Hi everyone. So this question is asking us in the co-ordination complex Cocn 63 negative, which species acts as the Lewis space during its formation with Cobalt ion. Furthermore, determine the oxidation number of Cobalt and the co-ordination number of the formed complex. So here we have four different answer. Choices proposing whether or not either cyanide or Cobalt is the lowest base followed by different numbers for the oxidation state of Cobalt and the co-ordination number of the overall complex. Now recall first and foremost that a Lewis base is an entity or species that donates an electron pair to form a bond with a Lewis acid. No charges can make a Lewis base easiest to identify. And the reason I mentioned this is because recall that cyanide happens to be an anion with a negative charge. So the negative charge indicates that the given compound does in fact have electrons that can be donated, meaning that cyanide is the lowest space for this complex. So now let's consider the oxidation state of Cobalt in co CN six three negative recall that you can use the charge of the overall complex as well as the charge of individual liens to find the oxidation state of an unknown. Right. In this case, we do not actually know the oxidation state of cobalt. So I'm going to treat this as a variable X. Now, if I add together the oxidation state of Cobalt plus the charge of all of my cyanide ions, I should get the total charge of my compound which is negative three, right. So here I'm going to add to my ex the total charge that cyanide is contributing. So here I have six ions of cyanide and all of them have a charge of negative one. So my overall equation is that X being the oxidation state of Cobalt added to six multiplied by negative one should equal negative three which is the overall charge of my complex. And so X subtracted by six should give me negative three. Meaning that X which is the oxidation state of Cobalt is equal to positive three. So the oxidation state of Cobalt in the given complex is positive three. So now I can proceed with the co ordination number. Now recall that the co-ordination number of a given complex is the number of ligand attachment points to the central metal ion. Now, in this case, we only have one type of ligand which happens to be cyanide. And if you recall cyanide is mono dentate, which means that cyanide has one point of attachment to the central ion via one donor atom. So for every mono dentate ligand present in a given complex, the co-ordination number increases by one. So if cyanide contributes a co-ordination number of one and I have six ions of cyanide, my total co-ordination number is going to be six and there you have it. My answer is going to be option B in the multiple choice because my lowest base is cyanide, the oxidation state of cobalt is positive three and the co ordination number of the complex is six. And with that being said, thank you so very much for watching and I hope you found this helpful.