Preparation and Characterisation of Dinuclear Nickel(II) Complexes Containing N 3 Ni(μ 1,3 ‐SO 3 R) 2 (μ‐O 2 CR)NiN 3 Cores: Crystal Structures and Magnetic Properties of [Ni 2 (L2)(O 2 CCH 3 )]BPh 4 and [Ni 2 (L2)(O 2 CPh)]BPh 4 [H 2 L2 = Macrocyclic Ligand with a N 6 (SO 3 ) 2 Donor Set]

The preparation and characterisation of two new macrocyclic Ni II complexes containing N 3 Ni(μ 1,3 ‐SO 3 R) 2 (μ‐O 2 CR)NiN 3 cores are described. Complexes [Ni 2 (L2)(O 2 CMe)] + ( 4 ) and [Ni 2 (L2)(O 2 CPh)] + ( 5 ), where (L2) 2– represents a macrocyclic hexaaza‐bis(phenylsulfonato) ligand, were synthesised by H 2 O 2 oxidation of the respective parent complexes, [Ni 2 (L1)(O 2 CMe)] + ( 1 ) and [Ni 2 (L1)(O 2 CPh)] + ( 2 ), supported by the corresponding hexaaza‐bis(thiophenolate) macrocycle(L1) 2– . The compounds were characterised by means of elemental analysis, mass spectrometry, IR and UV/Vis spectroscopy. The crystal structures of the tetraphenylborate salts of 4 and 5 show that the bridging thiophenolato functions in 1 and 2 are in both cases converted to μ 1,3 ‐bridging sulfonato groups. The conversion to the sulfonato groups is accompanied by a drastic increase of the Ni ··· Ni distance from 3.483(1) Å in 1 and 3.491(1) Å in 2 to 4.543(1) Å in 4 and 4.5725(8) Å in 5 . The magnetic properties are also affected. In contrast to 1 and 2 , which exhibit an intramolecular ferromagnetic exchange interaction ( S = 2 ground state), the spins of the nickel(II) ( S i = 1 ions) in 4 and 5 are weakly antiferromagnetically coupled, the coupling constants J ( H = –2 J S 1 S 2 ) being –2.0 cm –1 ( 4 ) and –2.3 cm –1 ( 5 ), to produce a diamagnetic ( S = 0) ground state. Supporting DFT (density functional theory) calculations substantiate the experimental results.