Problem with quaternion weapon sway

Hello, I'm trying to make a script where the weapon the player is holding sway when you move around but I'm getting an error The type 'UnityEngine.Quaternion' does not have a visible contructor(BCE0024), this is the code public var defaultPosition : Quaternion;

 var swayAmount : float = 5.0;
 
 var swayX;
 
 var swayY;
 
 var swaySpeed : float = 5.0;
 
 var newPos : Quaternion;
 
 var gun : GameObject;
 
  
 
 function Start () {
 
     defaultPosition = transform.localRotation;
 
 }
 
  
 
 function Update () {
 
     swayX = Input.GetAxis("Mouse X") * Time.deltaTime * swayAmount;
 
     swayY = Input.GetAxis("Mouse Y") * Time.deltaTime * swayAmount;
 
     newPos = new Quaternion(defaultPosition.x - swayX, defaultPosition.y - swayY, defaultPosition.z);
 
     gun.transform.localRotation = Quaternion.Lerp(gun.defaultPosition, newPos, swaySpeed * Time.deltaTime)

Thanks for the help.