How to create an empty IOrderedEnumerable<DynamicNode> and IEnumerable<IGrouping<string, DynamicNode>>

I need a way to create an empty IOrderedEnumerable and IEnumerable<IGrouping<string, DynamicNode>>

//above IGrouping DynamicNode gets stripped out by stackoverflow

Reason: I create 3 empty list types (IOrdered, IGrouping, IEnumerable) then based on some other information (options a user specifies such as order by create date or group by month) I then call a function on it assigning a list of said type.

(short snippet)

//DOESNT WORK THIS IS THE PART I NEED
IEnumerable<DynamicNode> baseList = Enumerable.Empty<DynamicNode>();
IOrderedEnumerable<DynamicNode> orderedList =  (IOrderedEnumerable<DynamicNode>)Enumerable.Empty<DynamicNode>();
IEnumerable<IGrouping<string, DynamicNode>> groupedList = (IEnumerable<IGrouping<string, DynamicNode>>)Enumerable.Empty<DynamicNode>();
//ABOVE DOESNT WORK THIS IS THE PART I NEED

if (order)
{
    if (group)
    {
        groupedList = returnGroupedOrderedList(nodeList, ascending, useFeatured, groupBy, orderBy);
    }
    else
    {
        orderedList = returnOrderedList(nodeList, ascending, useFeatured, orderBy);
    }
}

Anyone know how to do it?