Soll ich Sie kontaktieren wann es mir passt? Da du eine förmliche Anrede benutzt empfehle ich dir es so zu formulieren: "Darf ich Sie kontaktieren wenn ich Zeit finde?" oder wenn es für eine wichtige Person ist wie z.B. (zukünftiger) Arbeitgeber, Behörden, ect..: "Ich würde mich gern mit Ihnen in Verbindung setzten, sobald es mir möglich ist"

*direct object of dative verbs, such

If you're asking about the difference between "Sie" and "Ihnen". "Ihnen" is the dative pronoun. That means it is used as the direct object dative verbs such as glauben, danken, empfehlen and about 40 more. Dative nouns and pronouns are also used as the indirect object of a sentence (normally the recipient of something). Such as in the sentence, "I give you the gift." "Ich gebe Ihnen das Geschenk." The dative is also used with some prepositions, aus, außer, bei, mit, nach, seit, von and zu. If I remember correctly, Dutch unfortunately doesn't have a distinction between accusative and dative, like in English. In this sentence, you're working with the direct object of a transitive verb phrase, "kontaktieren sollen," and direct objects of verbs are *usually* accusative, so you'll use Sie. Maybe you're not asking about accusative vs. dative at all, but either way, I hope this helps. :) Best of luck.