Hello,  I have a yield calculation to do for my lab write-up and im not sure what equation to start from, heres what i know so far.

we prepared an iron bipyridine complex, (which i calculated to be [Fe(bpy)3]^2+ from the spectrophotometer) by mixing 0.1 g of anhydrous ferrous chloride Fecl2 (dissolved in min amount of water) with 0.4g 2 ,2 - bipyridine(dissolved in min amount of ethanol). then added sodium tetrafluoroborate(not sure what this step was for?)

my question is for my yield calculation equation, do i use fecl2 or has that turned into a complex with water, [fe(h20)6]2+. Also how do i know which is the limiting reagent? this is what i've got for the equation so far -

[fe(h20)6] + 3Bipy --> [Fe(bpy)3] + 6h20

if this is right, to calculate the moles of fe(h20)6 do i use the mass of fecl2?

any help is appreciated