First Synthesis and Structural Characterization of Dinuclear M(III) Bis(μ-oxo) Complexes of Nickel and Cobalt with Hydrotris(pyrazolyl)borate Ligand

Synthesis and Crystal Structure of a Triply-Bridged Binuclear Cobalt(II) Dichloroacetate

“…This structural difference between 1 and other chemically analogous compounds may be traced to the unsymmetrical manner in which the -CHCl 2 groups of the carboxylato ligands take part in the formation of intermolecular C-H···Cl hydrogen bond contacts in the crystal structure of 1. The Co(1)···Co(2) separation of 3.7203Å in 1 is marginally longer than the corresponding separation of 3.675Å in the related compound Co 2 (µ-OH 2 ) (µ-CHCl 2 COO) 2 (7) 2.071 (2) Co (1) (1)⋅⋅⋅Co(2) 3.7203 ( The unit cell packing diagram shown in Figure 2 testifies that in addition to the strong intra-molecular O-H···O hydrogen bonds, several inter-molecular hydrogen bonding contacts of C-H···O and C-H···Cl types characterize the crystal structure of compound 1 ( Table 3). The C-H···Cl interaction is illustrated in Figure 3 along with an energetically significant intermolecular π-π interaction involving the pyridine rings.…”

“…It is also noted that the two Co-O(1) distances are unequal with Co(1)-O(1) being longer by 0.03Å than Co(2)-O(1). This however is not the case in general, because in several reported structures of analogous compounds of the type Co 2 (µ-OH 2 )(µ-RCOO) 2 (η 1 -RCOO) 2 (py) 4 the Co-(µ-OH 2 ) distances are equivalent or nearly equivalent 5,6,8,9,13 . This structural difference between 1 and other chemically analogous compounds may be traced to the unsymmetrical manner in which the -CHCl 2 groups of the carboxylato ligands take part in the formation of intermolecular C-H···Cl hydrogen bond contacts in the crystal structure of 1.…”

“…The structure of the complex is structurally similar to the active site of aminopeptidase and thus can be useful for understanding some of the relevant biological systems. Under our reaction conditions, the dichloroacetato ligand prefers to form compound 1 rather than a member of the closely related complexes of the type [M 2 (µ-CHCl 2 COO) 2 …”

“…Such complexes have also been studied for magneto-structural correlation, bioinorganic modeling and catalysis. Metal complexes of this type having the triply-bridged the [M 2 (µ-OH 2 )(µ-O 2 CR) 2 ] 2+ core have also been prepared and studied as structural models of the analogous diiron(II) core present in the non-heme respiratory protein hemerythrin 5 . The binuclear core in these complexes comprises of two carboxylate anions and a water molecule as bridging ligands.…”

The Role of the Coordination Modes of a Flexible Bis(pyridylamide) Ligand in the Topology of 2D Copper(II) Complexes

“…5a. The Cu-O hydroxy bond lengths are within the normal range [20,21], and the non-bonding Cu···Cu separations are 5.860Å (Cu(1)···Cu(1)#1), 3.355 (Cu(1)···Cu(2)#1), 3.194 (Cu(1)···Cu (2)), and 2.929Å (Cu(2)-Cu(2)#3), which is slightly different from those of 5.938, 3.471, 3.202, and 3.056Å in a related tetranuclear copper cluster previously reported [22].…”