var webUrl = window.location.protocol + "//" + window.location.host + _spPageContextInfo.webServerRelativeUrl;

var createDocSet = function(listName, folderName, folderContentTypeId){
    var listUrl = webUrl + "/" + listName;
    var folderPayload = {
        'Title' : folderName,
        'Path' : listUrl
    };

    //Create Folder resource
    return $.ajax({
        url: webUrl + "/_vti_bin/listdata.svc/" + listName,
        method: "POST",
        contentType: "application/json;odata=verbose",
        data: JSON.stringify(folderPayload),
        headers: {
            "Accept": "application/json;odata=verbose",
            "Slug": listUrl + "/" + folderName + "|" + folderContentTypeId
        }
    });
};