Two isomers have the same formula but different structures: Co(H2O)5SCN, CO(H2O)5NCS. The 5's mean 5-H20's. Draw each of these structures and explain the difference between the two? I don't even know where to begin. I appreciate any kind of help at this point. Thanks!
We can't draw structures on the board but you can on a sheet of paper.
1. Draw a parallelogram on a sheet of paper.
2. From the center of the parallelogram, draw vertical line above and below.
3. The coordination number of the Co compound you have drawn is 6. Notice that you have 6 "corners" on your structure. H2O goes on 5 of them and NCS (or SCN) on the other one.
4. The isomer is SCN on the other one. The only difference is in the Co-NCS bond versus the Co-SCN bond.
Thanks Dr. Bob! Along those same lines. Which of the following compounds have more than one isomer? PtCl5NH3, Co(NH3)4Cl2, Pt(CO)2Cl2, Rb3[Cr(CN)6] Thanks!
Two kinds of diagrams you need.
One is the parallelogram with vertical lines above and below for coordination number of 6. The other is a parallelogram with no lines (which has four corners) for a coordination of 4.
For PtCl5NH3, coordination number (which I will abbreviate as C.N.) of 6 so you want the octahedral (the 6 cornered one). There is only one isomer.
For Co(NH3)4Cl2 C.N. = 6, the octahedral complex is what you want, and it can have two isomers. One is the Cl at the top and Cl at the bottom (this is the trans isomer); the other one is Cl at top and the other Cl at any of the adjacent corners and this is the cis isomer.
For PtCOCl2, this is the square planar one, C.N. = 4 and it can have two isomers, the cis and trans. I'll leave that for you to draw. It's easy to see since the square planar complex is two dimensional and so is the sheet of paper on which you've made your drawing.
Don't let the Rb3[Cr(CN)6] confuse you. That is a compound that consists of the Rb^+ and the hexacyanochromate(III) anion(3- charge). The only part that can have isomers is the anion and since all of the ligands are the same there will be no isomers.
Thanks Dr Bob! You da man!
To draw the structures of Co(H2O)5SCN and Co(H2O)5NCS, we need to understand the coordination chemistry of cobalt(II) complexes. In these complexes, cobalt(II) serves as the central metal ion, surrounded by ligands (atoms or molecules) that coordinate to the metal through coordination bonds.
In both compounds, we have five water molecules (H2O) that coordinate to the cobalt ion. The difference between the two compounds lies in the additional ligand that is coordinated to the cobalt ion.
In Co(H2O)5SCN, the additional ligand is thiocyanate ion (SCN-). Thiocyanate ion is a negatively charged polyatomic ion that consists of sulfur (S) and nitrogen (N) bonded to a carbon (C). So, we have one thiocyanate ion coordinated to the cobalt ion alongside the five water molecules.
To draw the structure of Co(H2O)5SCN:
1. Start by drawing the cobalt ion (Co) as the central atom.
2. Place five water molecules (H2O) around the cobalt ion, forming octahedral coordination geometry.
3. Coordinate the thiocyanate ion (SCN-) to the cobalt ion by bonding the sulfur (S) atom to the cobalt ion.
In Co(H2O)5NCS, the ligand present is isothiocyanate ion (NCS-). Isothiocyanate ion is similar to thiocyanate ion but with the nitrogen (N) and sulfur (S) atoms switched. So, we have one isothiocyanate ion coordinated to the cobalt ion alongside the five water molecules.
To draw the structure of Co(H2O)5NCS:
1. Start by drawing the cobalt ion (Co) as the central atom.
2. Place five water molecules (H2O) around the cobalt ion, forming octahedral coordination geometry.
3. Coordinate the isothiocyanate ion (NCS-) to the cobalt ion by bonding the nitrogen (N) atom to the cobalt ion.
To summarize the difference between Co(H2O)5SCN and Co(H2O)5NCS:
The only difference between the two structures is the nature of the additional ligand coordinated to the cobalt ion. In Co(H2O)5SCN, the additional ligand is a thiocyanate ion (SCN-), while in Co(H2O)5NCS, the additional ligand is an isothiocyanate ion (NCS-). The difference lies in the arrangement of the sulfur (S) and nitrogen (N) atoms within the ligand molecule.