Filling 1.5 inches wide gaps between newly fitted metal door frame surround and brick wall
If it's a hollow metal doorframe, it's generally intended to be filled with a cement mortar mixture, and I'm surprised if the job was considered complete without doing that. I've lived in a cheap apartment where they didn't bother to do that, and was burgled since the unfilled doorframe easily flexed far enough away from the door to clear the lock bolts when the thieves pried it.

I suppose it's also possible that it's simply the wrong size door/frame, in which case filling in with material similar to the wall (right - the title says bricks, so split bricks and mortar) might be appropriate - or getting the right sized door, but that's a step backwards.

That building was so poorly constructed that a few years after I moved out, the roof tore off in a thunderstorm (it was not a tornado.)