Complex sentence: Not having reached an absolute majority the "CDU/CSU," they formed a grand coalition together with the social-democratic SPD after long coalition talks, making the head of the party Sigmar Gabriel vice-chancellor and federal Minister for Economic Affairs and Energy.
Split into simpler sentences: Not having reached an absolute majority the "CDU/CSU" had to find another partner. After long coalition talks they formed a grand coalition together with the social-democratic SPD, making the head of the party Sigmar Gabriel vice-chancellor and federal minister of economics and energy.