Thermally robust materials of the M(5-X-pyrimidin-2-olate) 2 type [M = Co, X = Cl (1(Cl)), X = Br (1(Br)), X = I (1(I)); M = Zn, X = Cl (2(Cl)), X = Br (2(Br)), X = I (2(I))] have been synthesized. Their X-ray powder diffraction structural characterization has revealed that they crystallize as vertical bar(4) over bar 2d diamondoid frameworks, isomorphous to those of the pristine [M(pyrimidin-2-olate)(2)](n) analogues (1H, M = Co; 2(H), M = Zn). The magnetic measurements of the 1(X) series at magnetic fields of 100, 300, and 5000 Oe reveal a weak ferromagnetic ordering taking place below the Neel temperature (T-N similar to 20 K), arising from spin canting phenomena of the antiferromagnetically coupled cobalt centers. Moreover, magnetic hysteresis studies carried out on the 1(X) series at 2 K reveal a strong dependence of both the coercive field H-coer (2500, 1000, 775, and 500 Oe for 1(Br), 1(Cl), 1(I), and 1(H), respectively) and the remnant magnetization M-rem (0.0501 mu(B) for 1(Br) and 1(Cl), 0.0457 mu(B) for 1(I), and 0.0358 mu(B) for 1(H)) on the 5-substituent of the pyrimidin-2-olates. The molecular alloys [Co(5-Y-pyrimidin-2-olate)(2)] (Y = Cl/Br, 1(Cl/Br)) and [Co(5-Y'-pyrimidin-2-olate)(2)] (Y' = Br/I, 1(Br /I)) have also been prepared and characterized, proving that they have intermediate properties. These materials combine interesting functional properties, such as chemical inertness, magnetism, photoluminescence, and (although weak) SHG activity.