I remember you can send coin with an unsync’ed client. The network will process your tx if there is enough fund in the paying address/output and tx fee.
You can also do it with cointoolkit I think, if you have the priv key.
in your case your wallet thinks you have already sent the coin. If the network doesn;t process your tx, you can have the client to display the fund again with -rescan. but you need to sync first for that.