Checking collision before instantiating prefab

Hello everyone,

in my code, I want to instantiate multiple prefabs while not having them collide with the main object the moment they are instantiated.
I checked the Scripting API and went through almost all of the possibilities to check for incoming collisions, and it seems that I am probably just missing something.
I'm providing the code which is relevant.

 void SafeInstantiate(GameObject toInstance)
 {
    Vector3 rndmPos;
    Vector2 toCheck;
    // Pick a random position on the world map.
    rndmPos = new Vector3 (    Random.Range (-boundaryX - 1f, boundaryX + 1f),
                         Random.Range (-boundaryY - 1f, boundaryY + 1f),
                         0);
    // Prepare a Vector2 to check the collision with.
    toCheck = new Vector2 (rndmPos.x, rndmPos.y);
    Collider2D col = Physics2D.OverlapCircle (toCheck, 5.0f);
    int loopBreak = 0; // for anti-freezing purposes
    if (!col)
        Debug.Log ("col is null");
    while (col.name == "main" && loopBreak < 20) {
            // The toInstance coordinates seem to collide with the main object. Reroll the coordinates.
        Debug.Log ("Looping through");
        rndmPos = new Vector3 (    Random.Range (-boundaryX - 1f, boundaryX + 1f),
                                             Random.Range (-boundaryY - 1f, boundaryY + 1f),
                                             0);
        toCheck = new Vector2 (rndmPos.x, rndmPos.y);
        col = Physics2D.OverlapCircle (toCheck, 5.0f);
        loopBreak++;
    }
    // No collision, safe to instantiate.
    Instantiate(toInstance, rndmPos, Quaternion.identity);
 }

Do you see anything that would prevent my code from working properly? Need any more details?