In the simplest terms, the corporation would need to be able to maintain a certain standing with each Empire to be able to wardec and maintain a wardec in that region - just having a structure and the defender having a structure isn’t enough.
This is just in high-sec only. If your corporation’s Empire standing in that region drops below a certain level - any active wars immediately end.
Something like 5.0 to deploy a structure and 7.0 or higher to issue a wardec. In addition, deploying a structure should have some bonuses for that corporation (only):
• Astrahaus (15% LP bonus), Fortizar (25% LP bonus)
• Athanor (15% mining yield bonus), Tatara (25% mining yield bonus)
• Raitaru (15% manufacturing speed), Azbel (25% manufacturing speed)
And if your corporation’s Empire standings drop below 5.0, your structure(s) automatically go suspect. The idea here is that if you want to play in the carebear sandbox - you’re going to have to do at least a little carebearing yourself…