Coordination compounds

Question

For each coordination compound provided below

K3[CrI6],[Cu(en)2(H2O)2]Cl2,Na3[Co(NO2)6], [Co(en)3]3+

give the following

the complex ion including the charge

the spectator ion

the name of the ligands

the coordination number

the charge for the transition metal ion

the number of unpaired electrons in the d orbitals

Answer 1

a) the complex ion including the charge - This is the central metallic ion + the ligands surrounding it; the overall charge is the charge of the metal ion + it's ligands

b) the spectator ion - AKA"counter ion" - It balances out the charge of the complex ion to create a compound.

c) the name of the ligands - ending is changed to "o", like "chloride" becomes "chloro"; other more complex ligands have their own names (like en = ethylenediamine)

d) the coordination number - This describes how many attachment sites to the central atom are there. This will either match the number of ligands or in the case on complex ligands, you have to know how many attachments the ligand can make.

e) the charge for the transition metal ion - The charge on the central metal ion... Find this based on the spectator ion charge coupled with the ligand charges.

f) the number of unpaired electrons in the d orbitals - determine the electron configuration of the central ion and determine how many electrons are in the d orbitals

K3[CrI6] - potassium hexiodochromium (III)

a) complex ion w/ the charge [CrI6]3- - The 3- comes from the fact that there are 3 K+ ions, so the complex ion has to be -3.

b) spectator ion - K+

c) name of ligands - Iodide ions become "iodo",

d) coordination # - 6 (6 I- ions attached to the Cr)

e) charge of transition metal ion Cr3+ ; 3 K+ + _X_ + 6 I- = 0 (neutral compound) ∴ X = 3

f) # of unpaired electrons in d orbitals - 3, the electron configuration of Cr is [Ar]4s13d5 and Cr3+ is [Ar]3d3 ∴ there are 3 unpaired electrons in the d orbitals

[Cu(en)2(H2O)2]Cl2

a) [Cu(en)2(H2O)2]2+

b) Cl-

c) (en) ethylenediamine, (H2O) aquo

d) 6 (water connects in one place each, -en connects in two places)

e) Cu2+

f) 1; Cu is [Ar]4s13d10 and Cu2+ is [Ar]3d9 ∴ there is only 1 unpaired electron in the d orbitals

Na3[Co(NO2)6]

a) [Co(NO2)6]3-

b) Na+

c) NO2-, "nitrito-N" or "nitro"

d) 6

e) Co3+

f) 4s23d7 --> 3d6 ∴ 4 unpaired electrons

[Co(en)3]3+

a) [Co(en)3]3+

b) none given

c) ethylenediamine

d) 6 (2 for each en)

e) 3+, -"en" is neutral

f) 4s23d7 --> 3d6 ∴ 4 unpaired electrons

I suggest maybe taking a look at this as well. It has some nice explanations.

https://www.mioy.org/uploads/1/3/9/1/13912136/crystalfieldtheory-cft.pdf