from typing import Dict
from typing import Tuple


def check_negative_frequencies(
    mol: Dict
) -> Tuple[bool, None]:
    """
    Check if a molecule contains any negative frequencies.
    
    Args:
        mol (Dict): A dictionary representing a molecule entry in LIBE
        
    Returns:
        Tuple[bool, None]: if the molecule has a negative/imaginary frequency,
        then return True; otherwise, return False
    """
    
    if mol["vibration"] is None:
        return False, None
    
    if any([x < 0 for x in mol["vibration"]["frequencies"]]):
        return True, None
    else:
        return False, None