i can not conect my iphone 5s to my imac, I get a mesage from i tunes that it can not conect to de phone

That's the issue 🙂

iTunes 12.0 was released in October, 2014. It cannot possibly support iOS 11.

You need at least OS X 10.10.5 or Windows 7 to use the current iTunes (12.7.3).

Are you using iTunes 12.7 or later? This is required to communicate to iOS 11 or later.

If iTunes doesn't recognize your iPhone, iPad, or iPod - Apple Support

Glad that helped.

Enjoy your Apple gear.