When using the Business Object Lead You cannot find the field Account Name as an option of Placeholder for a Workflow Rule.
Reproducing the Issue
1. Go to Administrator Work Center -> Workflow Rules View.
2. Create/Edit Workflow Rule XYZ (XYZ represents the Workflow Rule ID) with Business Object Lead.
3. Go to Define Actions.
4. In the Placeholders section, see that Account Name is not available.
Company is the one Placeholder that refers to the Account Name for Workflow Rules that use the Lead as Business Object.
Use the Placeholder Company.
KBA , LOD-CRM-EMP , Employee , How To