Baggies chief executive Xu Ke has identified the former Wolsburg manager as the man to take the club forward with an official approach having been made to Barnsley last week.
The French-born 45-year-old, who has German Citizenship, is understood to be keen to move to The Hawthorns.
And the Championship rivals are now negotiating a compensation fee – with Ismael understood to have a £2million release clause in his contract.
His potential arrival, though, has led to the brakes being put on Harper’s move to Ipswich.
The Birmingham-born star has been set to join the League One side for a number of weeks with it understood he has already agreed terms and completed a medical at Portman Road.
But the move is yet to go through with Albion understood to want to make sure their new boss – whoever that turns out to be – is happy to let the midfielder leave.
Ismael guided Barnsley to a fifth placed finish in the Championship last season with a very young Tykes side.
The former Bayern Munich defender’s high pressing style often relies on youth – with Harper potentially a player he would be keen on.
The 21-year-old’s departure will also leave Albion with just two senior central midfielders in Jake Livermore and Romaine Sawyers, both of whom found themselves out of favour last season.
It is understood Ipswich have agreed a £500,000 deal for Harper that could reach £1million if all clauses are met.
But while that is a significant fee, it is not enough to drastically change what Albion will be able to do in the transfer market this summer.
And for that reason, the Baggies have delayed completing the deal in case the new boss wants to cast an eye over Harper in training.