Let's see how transition metals have special ion and properties in A-Level Chemistry!
An ion or molecule with a lone pair of electrons that forms a coordinate bond with a transition metal is called a ligand. When ligands surround the central metal ion, it forms a complex ion.
The ligands may be unidentate - they form one coordiante bond; bidentate or multdentate.
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/4979856/984195_34195.png)
Unidentate ligands include H2O, NH3, Cl-:
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/4979856/679193_717776.jpeg)
Bidentate lignands include NH2CH2CH2NH2 and C2O4:
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/4979856/175586_571536.jpeg)
Multidentate ligands include EDTA4- (etheylenediamminetetraacetate):
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/4979856/444427_815851.png)
Naming complex ions
- Number of each type of lignand
- Name of ligand
- Name of transition metal (ending in -ate if it is a negative ion)
- Charge on transition metal
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/4979856/828038_928730.png)
Shape of complex ions
The coordinate number tells us how many bonds the central metal ion forms with the ligand. It corresponds to how they are arranged.
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/4979856/126186_956010.png)
When the ligand is small, the shape is usually octahedral. With larger lignands such as Cl-, the complex ion ususally takes on a tetrahedral shape. In Tollen's reagent, the solution is a linear complex ion diammine silver(I) [Ag(NH3)2]+:
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/4979856/911593_686477.png)
With nickel and platinum, sqaure planar complexes may form:
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/4979856/652494_178910.jpeg)
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/4979856/681848_75670.jpeg)
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/4979856/405495_760352.jpeg)
Drafted by Eunice (Chemistry)
References
https://lavelle.chem.ucla.edu/forum/viewtopic.php?t=69339
https://www.breakingatom.com/learn-the-periodic-table/complex-ions