Syntheses, Structures and Magnetic Properties of Trinuclear Cu^IIM^IICu^II (M = Cu, Ni, Co and Fe) and Tetranuclear [2×1+1×2] Cu^IIMn^II–2Cu^II Complexes Derived from a Compartmental Ligand: The Schiff Base 3‐Methoxysalicylaldehyde Diamine Can also Stabilize a Cocrystal

Abstract

Abstract The present investigation describes syntheses, characterization and studies of the mononuclear compound [Cu II L⊂(H 2 O)] ( 1 ), the triangular, trinuclear monophenoxido‐bridged compounds [{Cu II L} 2 M II (H 2 O) 2 ](ClO 4 ) 2 · n H 2 O [ 2 (M = Cu, n = 0), 3 (M = Ni, n = 3), 4 (M = Co, n = 0), 5 (M = Fe, n = 0)] and the tetrametallic self‐assembled complex [{Cu II LMn II (H 2 O) 3 }{Cu II L} 2 ](ClO 4 ) 2 · H 2 O ( 6 ) derived from compartmental Schiff base ligand, H 2 L, which is the [2+1] condensation product of 3‐methoxysalicylaldehyde and trans ‐1,2‐diaminocyclohexane. Single‐crystal X‐ray structures of 2 , 5 and 6 were determined. Two pairs of terminal ··· central metal ions in the trinuclear cores in 2 and 5 are monophenoxido‐bridged. Interestingly, the CuO 6 and FeO 6 environments have tetragonally compressed octahedral geometries. On the other hand, the structure of 6 reveals that it is a [2×1+1×2] cocrystal of one diphenoxido‐bridged dinuclear [Cu II LMn II (H 2 O) 3 ] 2+ dication and two mononuclear [Cu II L] moieties. Cocrystallization in 6 takes place as a result of water encapsulation. The variable‐temperature (2–300 K) magnetic susceptibilities of compounds 2 – 6 have been measured. The exchange integrals obtained are: the Cu II 3 compound 2 , J = –78.9 cm –1 ; the Cu II Ni II Cu II compound 3 , J = –22.8 cm –1 ; the Cu II Co II Cu II compound 4 , J = –7.8 cm –1 ; the Cu II Fe II Cu II compound 5 , J = –3.0 cm –1 ; the Cu II 3 Mn II compound 6 , J = –15.1 cm –1 . The monophenoxido‐bridging core in 3 and 4 has been proposed after comparison of the structures and magnetic properties of these two compounds with those of 2 , 5 and related other compounds. This paper presents rare examples of monophenoxido‐bridged Cu II M II Cu II (M = Cu, Ni, Co and Fe) compounds, provides an understanding of the structures from magnetic exchange integrals, and, most importantly, reports on the first example of a cocrystal derived from a 3‐methoxysalicylaldehyde diamine compartmental ligand.