Specific conductance of coordination complexes

Werner-Miolati data from Z physik. Chemie, 12, 35-55, 1893

Complex				charge	specific conductance					
[Co(NH3)6]Cl3			3		431.6					
[Co(NH3)6]Br3			3		426.9		
[Co(NH3)6](NO2)3		3		421.9		
[Co(NH3)5(H2O)]Br3		3		412.9		
[Co(NH3)4(H2O)2]Br3		3		399.5		
[Co(NH3)3(H2O)3]Br3		3		383.8			
[Co(NH3)5Cl]Cl2			2		261.4			
[Co(NH3)5(ONO)]Cl2		2		258.4					
[Co(NH3)5Br]Br2			2		257.6			
[Co(NH3)5(NO2)]Cl2		2		246.4					
[Co(NH3)5(NO2)]Br2		2		236.8					
[Co(NH3)5(NO2)](NO2)2		2		234.4					
[Co(NH3)4(CO3)]Br		1		106					
cis-[Co(NH3)4(NO2)2]Cl		1		100.7					
trans-[Co(NH3)4(NO2)2]Cl	1		98.35					
[Co(NH3)3(NO2)3]		0		<0					
K[Co(NH3)2(NO2)4]		-1		99.29					
K2[Co(NH3)(NO2)5] - unknown	-2		?					
K3[Co(NO2)6] **			-3		~560					
** data for Fischer's salt from N. Dhar	"Z. anorg Chem.", 80,48,1913							

From this information it is possible to average the results to find the range expected for each type of charged complex.

Charge	Specific Conductance	
	Min	Ave	Max
3	383.8	412.8	431.6
2	234.4	249.2	261.4
1	98.35	101.7	106
0		<10
-1		99.29
-2		?
-3		~560

Suggestion for a reading assignment A gap exists in the chart for a dianionic cobalt complex. A few complexes of this type have been prepared since then, such as K2[Co(NH3)CN5] and [Co(NH3)C2O4(NO2)3]2-. What information can you find about these complexes? Have their specific conductances been measured? Why not suggest a few others that could be used instead? The sort of complex you would need is [Co(NH3)(C2O4)2(NO2)]2-. What others can you think of?

Return to Chemistry, UWI-Mona, Home Page
created March-97, last modified 16th May-97, rjl