One Dimensional Coordination Polymer of Nickel(II)-Squarate with N,N,N′,N′-tetramethylethylenediamine, {[Ni(μ-sq)(H2O)2(tmen)]·H2O}n

Polynuclear and polymeric squarato-bridged coordination compounds

“…This category represents not only the major species for the bis-μ 1,3 but also for the rest of the bridging-squarato compounds. It includes mono-squarato catena -[M II (μ 1,3 -C 4 O 4 )(DMSO) 2 (H 2 O) 2 ] 37–65 {M = Mn, Co, Zn ( 18–20 )}, 37 catena -[Cu 2 ( 2 , 2 ′- bpy ) 2 (μ 1,3 -C 4 O 4 )(μ-OH) 2 ]·4H 2 O ( 21 ), 35 b [M II (L) x (μ 1,3 -C 4 O 4 )(H 2 O) y ] 37–65 where L = py, x = y = 2: M = Co, Ni, Cu, Zn ( 22–25 ); 38 L = H 2 O, x = y = 2: M = Mn, Fe, Co, Ni, Cu, Zn ( 26–30 ); 27,42 L = 4-Meim: M = Co, Ni, Cd, x = y = 2 ( 31–33 ); 44,46 L = 2-Meim, M = Co, x = y =2 ( 34 ); 46 L = 4-pyca, x = y =2: M = Co, Cu ( 35 , 36 ); 49 L = DMF: M = Mn, Co, Ni, Cu, Zn, x = y = 2 ( 37–41 ); 51,52 L = pz, M = Ni, x = y =2 ( 42 ); 51,52 L = 1-Meim, x = y =2: M = Zn, Cd ( 43 , 44 ); 53 L = bpp, x = y = 2: M = Mn, Fe, Co 45–47 ); 54,55 L = im, x = y = 2: M = Co, Cu, Zn ( 48–50 ); 27,56 L = DPA, M = Zn, x = y =1 ( 51 ); 11 L = Me 4 en, x = 1, y = 2, M = Ni ( 52 ); 45 L = 3-pypz, x = 2, y = 0, M = Cd ( 53 ); 48 L = L 1 , x = 2, y = 0, M = Cu ( 54 ); 57 L = L 2 , x = 2, y = 0, M = Ni ( 55 ); 44 L = L 3 , x = y = 1, M = Cu ( 56 ); 58 L = pic, x = 2, y = 0: M = Cu, Zn, Cd ( 57–59 ); 59 a L = ea, x = 2, y = 0, M = Cu ( 60 ); 60 L = 2-pEtOH, x = 2, y = 0, M = Cu ( 61 ); 61 L = bimam, x = 2, y = 0, M = Cu ( 62 ) 62 and catena -[Cu 2 (bimam) 2 (μ 1,3 -C 4 O 4 )Cl 2 ] ( 63 ), 63 as well as bis-squarato catena -[M II (μ 1,3 -C 4 O 4 ) 2 (H 2 O) 2 ] 2− (M = Ni, Cu, Zn, Mn and Cd ( 64–68 )) complexes. …”

Mixed-Ligand Uranyl Squarate Coordination Polymers: Structure Regulation and Redox Activity

“…Squaric acid (3,4-dihydroxycyclobut-3-ene-1,2-dione, namely as H 2 C 4 O 4 or H 2 SA ) is a small-molecule cyclic compound belonging to the family of oxocarbons H 2 C n O n ( n = 3–6 for deltic, squaric, croconic, and rhodizonic acids, respectively; see Scheme a). , Because of the characteristic electron delocalization for the deprotonanted form of squaric acid (Scheme b), the corresponding squarate (C 4 O 4 2– , SA 2– ) ion has the attributes of structural rigidity, good coplanarity, and high symmetry. Furthermore, this electron-rich system can undergo oxidation reaction and has good redox activity. ,− To date, SA 2– has been widely used as a versatile ligand with various coordination modes to construct various CPs with novel extended connection, including one-dimensional (1D) chains, − two-dimensional (2D) networks, , and three-dimensional (3D) frameworks. , Meanwhile, it also acts as hydrogen bonding acceptor or a π–π stacking constructor for the stabilization of extended 3D supramolecular networks. ,− However, up to now, compared to coordination polymers based on transition-metal-squarate compounds, only a limited number of actinide-based squarate coordination compounds have been reported, and there is still broad room for further development of actinide-based compounds. Cahill et al studied hydrothermal synthesis of uranyl squarates and the effects of pH and hydrolysis of uranyl cations on reaction products of uranyl nitrate and squaric acid. , Forbes et al probed the effects of uranyl oligomerization, squaraic acid coordination, and intermolecular interactions on the formation of structural building units using a combination of solid and solution spectroscopy .…”