I have worked on the syntactic diachrony of finite clauses introduced by (functional) prepositions in the history of Spanish, with a comparative perspective (Portuguese, French, Italian). You can read about this in these publications:
-2013. Prepositional Clauses in Spanish. A Diachronic and Comparative Syntactic Study. Berlin: De Gruyter.
-2014.“Dequeísmo and queísmo in Portuguese and Spanish”. In P. Amaral and A. M. Carvalho (eds.): Portuguese-Spanish Interfaces. Diachrony, synchrony, and contact, Amsterdam/Philadelphia: John Benjamins, 95-120.
-2013. “Clausal substantivization in Spanish: syntax and constraints”, Australian Journal of Linguistics 33.2: 106-120.