def METHOD_NAME(xyzf):
    # setting properties
    xyz = mol3D()
    xyz.readfromxyz(xyzf)
    # getting idxs of interest
    midx = xyz.findMetal()[0]  # monometallic complexes
    # list of idx of the first-coord sphere
    fidx_list = xyz.getBondedAtoms(midx)
    fsym_list = []
    for idx in fidx_list:
        sym = xyz.getAtom(idx).sym
        fsym_list.append(sym)
    return fsym_list