$sourcePath = 'C:\Users\steve\Desktop\New folder'

Get-Childitem $sourcePath -File | Foreach-Object `
    {
     $target = -join($sourcePath,"\", $_.FullName.Substring($_.FullName.LastIndexOf("."), $_.FullName.Length - $_.FullName.LastIndexOf(".")).Substring(1))
     echo $target
     mkdir $target
     cd $sourcePath
     Move-Item $_ -Destination $target
    }