Stimulated by the efficiency exhibited by enzymes, chemists have sought not only to understand the mechanistic basis for enzymatic reactions, but also to reproduce and even surpass their capabilities. The complementary fields of enzymatic catalysis and transition metal based asymmetric catalysis have recorded many successes in the field of enantioselective reaction development. One question at the interface of these
The best fit for c M T versus T in the range of 9 ± 300 K (solid line shown in Figure a) leads to the following parameters: J/k 71.18 K, J'/k 0.58 K, g 2.07 and R 2.0 Â 10 À2 (R S[(c M ) obs À (c M ) calcd ] 2 /S[(c M ) obs ] 2 ). The small positive J' value implies that the exchange interaction through the axial asymmetrical EE bridging azide is very weakly ferromagnetic. This is mainly because of the strict orthogonality of s x and p z azide orbitals. [3b] The low temperature magnetic data (2 ± 20 K) measured at different external fields between 200 Oe to 10 kOe indicate that the value of c M T increases greatly with decreasing magnetic field. This result suggest that the presence of field-saturation effects in addition to the possible weak inter-layer antiferromagnetic interaction may cause the decrease of c M T below 9 K.
Very recently, Monfort et al. [11] reported a 2D molecular material with Ni II centers and azide units that shows metamagnetic behavior. Our work supplies the first 2D metal ± azide bridged compounds with long-range ferromagnetic ordering properties. Details of further magnetic measurements can be found in the Supporting Information.
Experimental Section
A solution of CuCl 2 ´6 H 2 O (1 mmol) in methanol (10 mL) was added to a solution of NaN 3 (2 mmol) and the hydrobromide salt of benzylamine (1 mmol) in H 2 O (25 mL). A Black-brown precipitate formed over several minutes. The solid was collected by filtration and washed with methanol and diethyl ether (yield ca. 75 %). Elemental analysis calcd for C 7 H 9 CuN 7 (%) : C 32.97, H 3.53, N 38.47, Cu, 24.93; found: C 32.78, H 3.70, N 38.56, Cu 25.00; IR: n Ä max 2094, 2056 cm À1 (n asym N 3 ). Black needles suitable for single-crystal X-ray analysis were obtained by slow evaporation of the filtrate in air.