ti pagheremo per lavorare
{vs}: ti pagheremo un salario per lavorare
== pay you (a salary)
I've just heard that the personal pronoun "ti" actually serves different grammatical functions in these two similar sentences, though they both seem like an indirect object with the meaning of "to you".
In the first sentence, ti is the direct object (complemento oggetto), in the second case it is an indirect object (complemento di termine).
With the pronoun after the verb the two sentences would become
Pagheremo te per lavorare
Pagheremo un salario a te per lavorare
When the pronoun is in front of the verb it takes the form ti in both cases. The same opposition is in
Ti amo (amo te)
Ti voglio bene (voglio bene a te)
The verb pagare has the curious, but by no means unique, feature that it can be construed in more than one way: it may admit as a direct object any of the following:
(I believe that the two first constructions hold for English too, but this is beside the point.)
So, the first of the sentences in the question, Ti pagheremo per lavorare may be, a bit awkwardly, rephrased Pagheremo te per lavorare (as in the Gigi example), and “ti” (or “Gigi”) is the direct object.
The sentence Ti pagheremo un salario per lavorare, on the other hand, can be rephrased as Pagheremo a te un salario per lavorare, so the direct object is “un salario” here.
The misleading detail is that the pronoun ti is, “accidentally”, both the dative and the accusative form of tu. It all would be different in the third person, or with a noun:
Lo pagheremo per lavorare
versus
Gli pagheremo un salario per lavorare
or
Pagheremo Gigi per lavorare
versus
Pagheremo un salario a Gigi per lavorare.
