The ac-susceptibilities of the isostructural metal-organic magnets, M-II(N(CN)(2))(2)(M = Ni (1), Co (2) and Fe (3)) have been studied as a function of temperature and pressure. Large variation in behaviors has been observed: the transition temperature initially increases in all three compounds and at higher pressures that for (1) saturates, for (2) decreases and for (3) increases continuously, These behaviors an due to the competition between antiferromagnetic (t2g <-> e(g)) and ferromagnetic (t(2g) <-> t(2g) and e(g) <-> e(g)) interactions to the most dominant exchange pathway, M ... N=C-N ... M. A mechanism for the magnetic ordering is proposed.