Why does Invoke-Command fail with multiple-paramater command?

$robocopy = ("$env:SystemRoot\System32\robocopy.exe ")
$source = '"\\MYSERVER\netlogon\MyFolder\MyStuff" '
$destination = '"C:\MyFolder\MyStuff" '
$options = "/MIR R:1 W:1 /XJ "
$excFiles = '/XF "test.txt" today.doc" '
$excDirs = '/XD "test" "today" '
$log = '/NFL /NDL /LOG:"C:\mycopy.log"'
Write-Host "------------------------------------"
$robocopy
$source
$destination
$options
$excFiles
$excDirs
$log
Write-Host "------------------------------------"
$command = $robocopy+$source+$destination+$options+$excFiles+$excDirs+$log
$command
Invoke-Command $command

------------------------------------
C:\Windows\System32\robocopy.exe
"\\US0TE0DC0A01\netlogon\MyFolder\MyStuff"
"C:\MyFolder\MyStuff"
/MIR R:1 W:1 /XJ
/XF "test.txt" today.doc"
/XD "test" "today"
/NFL /NDL /LOG:"C:\mycopy.log"
------------------------------------
C:\Windows\System32\robocopy.exe "\\MYSERVER\netlogon\MyFolder\MyStuff" "C:\MyFolder\MyStuff" /MIR R:1 W:1 /XJ /XF "test.txt" today.doc" /XD "test" "today" /NFL /NDL /LOG:"C:\my
copy.log"
Invoke-Command : Parameter set cannot be resolved using the specified named parameters.
At C:\invokeRobocopy.ps1:20 char:1
+ Invoke-Command $command
+ ~~~~~~~~~~~~~~~~~~

The command appears to be quoted properly for execution on the command line.

How do I format these multiple parameters for Invoke-Command?