Unconventional relatives and antecedents in disguise: german clefts and free relative clauses

German clefts and free relatives are generally considered relative clauses. However, there is something special about them. Clefts resemble regular relative clauses but crucially differ from them in their semantics and functions, whereas free relatives lack an overt antecedent. Why are German clefts extremely marginal and free relatives highly constrained? Is there anything in common between these two different types of unconventional relatives? The exploration of the mechanisms which rule their uses will disclose the fil rouge which binds the two constructions. The hypothesis is that both structures imply a silent head, i.e. an antecedent in disguise, which is responsible of the syntax-semantics mismatch in clefts and of the constraints which limit the acceptability of German free relatives.