I Lab Services 

4.25.1  Limitations for BCF 

The algorithm does not calculate the BCF for the following chemical structures: 

Structures containing atoms other than C, H, O, S, N, and F in possible chemical 

surroundings or structures containing atoms P, Cl, Br, I, Se, Si, Ge, Pb, Sn, As, and B that 

are not within the chemical surroundings shown below (note that A denotes any atom out 

of C, O, S, N, F, or any group listed below

7

):   

A

A

A

A

A

Cl

A 

B

A

Ge

A

P

A

Se

A

8

A

A

A

A

A

A

A

Se

A  

Br

A 

Sn

A

P

A

A

A

A

A

A

A

I

A 

Pb

A

As

A

A

A

Structures containing atoms in non typical valence states (see the Elements Table in the 

ACD/ChemSketch for information on individual atomic valences); 

Structures containing non covalent (co ordination) bonds; and 

Structures containing more than 255 heavy atoms or 10 ionization centers. 

Additionally, the algorithm does not take into account the specific features of different geometric 

isomers, stereomers, conformers, and isotopes.  The algorithm does not correct its prediction for 

long range non covalent bonding, intra molecular shielding, or inter molecular association. 

7

 This group cannot be a part of a cycle unless otherwise stated. 

8

 This fragment can be a part of an aromatic cycle. 

ACD/I Lab via ChemSketch  

User's Guide 

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