Crystal structure of tetrakis(μ-n-butyrato-κ²O:O′)bis[chloridorhenium(III)](Re—Re)

Abstract

With an inversion center at the mid-point of the two ReIII atoms, the title compound, [Re2Cl2{O2C(CH2)2CH3}4], exhibits a paddle-wheel or lantern-type structure with four n-butyrate groups bridging two ReIII atoms in a syn–syn fashion. The axial chloride ligands together with the Re—Re quadruple bond [2.2330 (3) Å] complete an essentially octa­hedral geometry around each ReIII atom. There is little distortion, with an Re—Re—Cl bond angle of 176.18 (3)° and typical cis-O—Re—O bond angles ranging from 89.39 (11) to 90.68 (11)°. There are two mol­ecules in the unit cell, and no significant inter­molecular inter­actions were noticed between mol­ecules in the crystal.

The crystal structures of tetrakis(μ-n-butyrato-κ2O:O′)bis[bromidorhenium(III)] and tetrakis(μ-n-butyrato-κ2O:O′)bis[chloridorhenium(III)] acetonitrile disolvate

“…1). In the structure of [Re 2 Cl 2 (O 2 CC 3 H 7 ) 4 ] without cocrystallizing solvent, the torsion angles vary more [C1-C2-C3-C4 = À55.2 (5) and C5-C6-C7-C8, 179.5 (4) ] (Thomson et al, 2014), similar to those observed in (1) ( Table 1).…”

“…The X-Re-Re-X bonds in (1) and (2) are nearly linear, as can be seen in the Re-Re-Br [175.018 7] and Re- ] bond angles, and are comparable to those observed in similar compounds (Collins et al, 1979;Thomson et al, 2014). The Re-Cl bond length [2.5056 (5) Å ] of (2) is similar to those of the previously published analog without co-crystallized acetonitrile (Thomson et al, 2014) (Bennett et al, 1968;Collins et al, 1979). The Re-Br bond length [2.6712 (3) Å ] of (1) is slightly longer than the Re-Br bond [2.603 (1) Å ] found in [Re 2 Br 2 (O 2 CC(CH 3 ) 3 ) 4 ] (Collins et al, 1979).…”

“…The structure of (1) is isotypic with the chlorido analog published by Thomson et al (2014). Inspection of the torsion angles of the hydrocarbon chains reveals the possible effect of the co-crystallization of solvent in [Re 2 Cl 2 (O 2 CC 3 H 7 ) 4 ].…”

“…The title complexes are of the structural type classified as paddlewheel complexes, where the four carboxylate ligands bridge the two metal atoms, creating a paddlewheel appearance. A variety of these dirhenium(III) tetracarboxylate complexes were synthesized by Cotton et al (1966) (Bennett et al, 1968), [Re 2 (ReO 4 ) 2 (O 2 CC 3 H 7 ) 4 ] (Calvo et al, 1970), [Re 2 X 2 {O 2 CC(CH 3 ) 3 } 4 ], where X = Cl or Br (Collins et al, 1979), [Re 2 Cl 2 (O 2 CCH 3 ) 4 ] (Koz'min et al, 1980), and [Re 2 Cl 2 (O 2 CC 3 H 7 ) 4 ] (Thomson et al, 2014) have been reported. For additional dirhenium tetracarboxylate structures, see: Shtemenko et al (2001), Cotton et al (1997), and Vega et al (2002).…”