I'm from Argentina and we use accents in words. Is this URL is worst for pagerank:
Yes and no. It will probably improve your Spanish language queries because Google will probably assume the page is intended primarily for Spanish speakers. It could negatively impact English language searches in some cases, depending on various factors such as your incoming links, page specific language data, etc.
I've noticed the language boost one two of my sites where the domain name and some page titles are in Italian or Spanish. Since the keyword terms were poorly served in those languages, I started getting significant traffic from language/region specific Google sites although the on-page language was primarily English.
Of course, if you're wanting to target primarily English language traffic then you need to use only English in your URL, your page metadata and for the majority of your content. Another thing to consider is that most English language keywords won't have keys for accented characters, thus making it difficult for users to directly type in your URL.
AFAIK, google bot is not NLP(natural language processing) equipped. IF It was then it could be possible for people to get low search result rank based on grammar errors and US/UK word choices. It is possible to weight them if the page is archived for long time.Google does have local presence in many countries and they do crawl local pages from certain countries. You may not able to rank in english territories in such cases with local accent words but you'll definitely compete within native search results. As google algorithm being guarded secret it's not easy to make conclusion on this. Anchor text with accent word choice based in geolocation may have impact depending on the highly searched keywords.But this doesn't apply to many top keywords and results still remain same.