What is up with this PowerShell command line quoting/escaping?

I obviously don't know what I'm doing.

I have finally got this PowerShell command to work. But I can't figure out why it works.

My concern is the final "" characters:

    &"C:\Program Files\IIS\Microsoft Web Deploy\msdeploy.exe" `
    -verb:sync `
    -source:contentPath="$build_directory\deploy" `
    -dest:contentPath="$server_temp_directory,computerName=$server,username=$server_username,password=$server_password" `
    -verbose `
    -postSync=runCommand="powershell -NoLogo -NoProfile -Command $server_temp_directory\remotetasks.ps1 Deploy""

Why do I need double double-quotes?

My IDE (PowerGUI) says the line is not ended correctly, but it is the only way I can make the command run as wanted.

What is it, that I - and the IDE - don't know about quoting in PowerShell?

A little output from echoargs:

If I run:

echoargs -postSync=runCommand="powershell -NoLogo -NoProfile -Command $server_temp_directory\remotetasks.ps1 Deploy""

I get:

Arg 0 is <-postSync=runCommand=powershell -NoLogo -NoProfile -Command \remotetasks.ps1 Deploy>

If I run without the double double-quotes, I get:

Arg 0 is <-postSync=runCommand=powershell>
Arg 1 is <-NoLogo>
Arg 2 is <-NoProfile>
Arg 3 is <-Command>
Arg 4 is <\remotetasks.ps1>
Arg 5 is <Deploy>

Another thing to notice is that the above command does only work if it uses = instead of : in the last argument.

This won't work:

-postSync:runCommand="powershell -NoLogo -NoProfile -Command $server_temp_directory\remotetasks.ps1 Deploy""

I have tried the array solution like this:

$arguments = @("-verb:sync",
               "-source:contentPath=$build_directory\deploy",
               "-dest:contentPath=$server_temp_directory,computerName=$server,username=$server_username,password=$server_password",
               "-verbose",
               "-postSyncOnSuccess:runCommand=powershell -Command $server_temp_directory\remotetasks.ps1 Deploy")
&"C:\Program Files\IIS\Microsoft Web Deploy\msdeploy.exe" $arguments

I still get the same error:

Error: Unrecognized argument '"-postSyncOnSuccess:runCommand=powershell -Command c:\temp\kslog\remotetasks.ps1 Deploy"'. All arguments must begin with "-".

Am I doing some new thing wrong here?