posredovati

1. (between parties) to mediate
   Evropska unija posreduje u pregovorima Beograda i Prištine. — The European Union mediates in the talks between Belgrade and Pristina.
   Stalno moram da posredujem između brata i sestre. — I constantly have to mediate between my brother and sister.
2. (for someone) to intervene; to intercede
   Ujak je posredovao da ga prime na posao. — His uncle intervened to get him the job.
3. (in a deal) to act as an agent; to broker
   Ova agencija posreduje u prodaji stanova. — This agency brokers apartment sales.

Usually: posredovati u + loc. (in what), između + gen. (between whom), za + acc. (for whom).