Set variable different values depending on IF ELSE condition in batch file

My goal is to set %PF% variable to C:\ProgramFiles(x86)\MSBuild\ on x64 machines and to C:\ProgramFiles\MSBuild\ on x86 machines. I can easily achieve that such way

IF DEFINED ProgramFiles(x86) SET PF=%ProgramFiles(x86)%\MSBuild\
IF NOT DEFINED ProgramFiles(x86) SET PF=%ProgramFiles%\MSBuild\

But I want to do that in a single IF ELSE statement.

That one

IF DEFINED ProgramFiles(x86) (SET PF=%ProgramFiles(x86)%\MSBuild\) ELSE (SET PF=%ProgramFiles%\MSBuild\)

fails with unexpected "\MSBuild\" error.

That one

IF DEFINED ProgramFiles(x86) (SET PF="%ProgramFiles(x86)%\MSBuild\") ELSE (SET "PF=%ProgramFiles%\MSBuild\")

runs without errors.

But the result value is not what I need ("%ProgramFiles(x86)%\MSBuild\" - instead of "C:\ProgramFiles(x86)\MSBuild\" on x64 machine for example).

So is that possibe?