First Experimental Structure of a 1:1 Metal Complex with a PQQ Cofactor Derivative outside Dehydrogenase Enzymes

Abstract

Qualitatively similar metal coordination as in PQQ-dependent bacterial dehydrogenases was observed for the PQQ triester in the model complex I, although the unusual five-coordinate copper(I) center is smaller and softer than the Ca2+ ion of the native enzymes. The ambidentate PQQ thus prefers coordination through the O(5)/N(6)/O(7‘) atoms even without additional support from the protein scaffold.

Controlling the redox properties of a pyrroloquinolinequinone (PQQ) derivative in a ruthenium(ii) coordination sphere

“…The dissociation of the carbonyl O atom should be due to the weak coordination as reported for a Cu I -PQQTME complex, in which the coordination bond length has been reported to be the longest (2.579(4) Å) among other coordination bonds involved. 26 As mentioned above, the DFToptimized structure of 2 (Fig. 2) also showed the longest bond length for Ru-O c (2.189 Å) to support the possibility of the dissociation of the methoxycarbonyl oxygen toward the coordination of MeCN, which should bind strongly to a Ru II centre.…”

(6-Acetyl-1,3,7-trimethyllumazine-κ3O4,N5,O6)bis(triphenylphosphine-κP)copper(I) hexafluoridophosphate

“…Crystal data [Cu(C 11 the CCDC database indicates only two previously reported Cu I P 2 NO 2 examples: the Cu(I) complex with the 2′,7′,9′-trimethylesther of pyrroloquinoline-quinone (Wanner et al, 1999) and the isostructural perchlorate salt of the title compound (Hueso-Ureña et al, 2008). The title compound shows a salt-like structure containing [Cu(DLMAceM) (PPh 3 ) 2 ] + cations (DLMAceM = 6-acetyl-1,3,7-trimethylpteridine-2,4(1H,3H)-dione, see Scheme 1) and octahedral hexafluorophosphate anions (Fig.…”

“…The lumazine ligand is arranged in a roughly perpendicular fashion (81.0°) to the above-mentioned trigonal plane, the metal ion lying 0.41 Å out of this plane; in this plane, there are two additional and very long Cu •••O4 and Cu•••O61 (2.466 (3) and 2.529 (3) Å, respectively). The final coordination polyhedron can be defined as an intermediate TBP/SP shaped polyhedron, since Addison's τ criterion (Addison et al, 1984) indicates a distorted square-pyramid (τ= 1/5, apical atom N5), whereas Muetterties and Guggenberger's calculation (Muetterties & Guggenberger, 1974) A close comparison of the coordination environments of the title compound and its related perchlorate one (Hueso-Ureña et al, 2008) with the Cu(I) complex of the 2′,7′,9′-trimethylesther of pyrroloquinoline-quinone (Wanner et al, 1999) indicates that both DLMAceM Cu(I) complexes show a little more unsymmetrical PPh 3 groups with a P1 atom occupying a somewhat more apical position than P2; thus, the difference between both Cu-P bond lengths in the DLMAceM complexes (0.034 Å for Cu/DLMAceM/ClO 4 and 0.026 Å for the title compound) is higher than in those reported by Kaim (0.014 Å) (Wanner et al, 1999). In addition to this, whereas the exocyclic carbonyl Cu -Cueva et al, 2003;Jiménez-Pulido et al, 2008).…”

“…For related literature on the coordination behaviour of pteridine and related ligands, see: Jimé nez Pulido et al (2001; Acuñ a-Cueva et al (2003); Hueso-Ureñ a et al (2008). For related literature on similar Cu I coordination environments, see: Wanner et al (1999); Hueso-Ureñ a et al (2008). For additional structural details quoted in the comment, see: Addison et al (1984); Cremer & Pople (1975); Janiak (2000); Muetterties & Guggenberger (1974); Spek (2009).…”

Coordinative Saturation of the Pterin Heterocycle by Ferrocenylcopper(I) Complex Fragments

“…The angle across this bridge is Cu3-O1-Cu1 = 167.394(2)°, indicating an almost linear type of bridging. The five-coordinate [17] Cu3 atom adopts a square pyramidal (C 4v ) type structure with weak bonding interaction to O 4 (O1). Three different coordination spheres, CuPN 2 O for Cu1, CuP 2 NO for Cu2, and CuPN 2 O 2 for Cu3 (Figure 1) are occurring in this structure, which contains both chelating (P3, P4) and bridging dppf units (P1, P2).…”