In Catalan-speaking countries / territories, the name Iu is both a one and two-syllable name, pronounced either EEoo (similar to the English digraph 'ew' within the words 'new' and 'few'), or EE-oo. The form Ïu is only pronounced EE-oo.
Though Iu is a classic Catalan name, it's not normally found among general personal name sites, and glad to see it here, as it's my personal favourite for a boy / male. It doesn't quite translate well in English, yet along with the name Ivo, the name Hugh (though a different origin) makes a good transliteration.