Surface immobilization of Mo6I8 octahedral cluster cores on functionalized amorphous carbon using a pyridine complexation strategy

Abstract

International audienceTetrahedral amorphous carbon (a-C) films have been grown by pulsed laser deposition to investigate a liquid phase process for surface immobilization of electroactive [Mo6Ii8]4 + transition metal cluster cores using a complexation reaction with a pyridine-terminated alkyl monolayer covalently bonded to the a-C surface (PyS–alkyl/a-C). These films are stable against thermally-assisted grafting of alkene molecules and the covalent Csingle bondC interface provides a robust monolayer/a-C assembly. Octahedral [Mo6Ii8]4 + cluster cores with iodine inner ligands and labile triflate apical ligands [Mo6Ii8(CF3SO3)a6]2 − have been immobilized through partial complexation in apical positions by surface pyridine groups (PyS). The remaining CF3SO3− apical ligands of [Mo6Ii8 (PyS)ay(CF3SO3)a6 − y] cluster units were further substituted with bromopyridine (Py-Br) to obtain air stable surface with expected final composition [Mo6Ii8 (PyS)ay(Py-Br)a6 − y]. The yield of the different reaction steps is followed by X-ray photoelectron spectroscopy, providing cluster coverage ΣMo6I8 = 9 × 1012 cm− 2. Each [Mo6I8]4 + cluster is bound to the carbon surface through multiple anchoring metal sites (NPYR = 3 or 4), indicating that pyridine-terminated alkyl chains are flexible enough to accommodate four bonds. Electrical transport through Hg//Mo6I8–PyS–alkyl/a-C/p-Si(111) junctions shows rectifying current–voltage characteristics but does not reveal any signature of cluster immobilization

MoII Cluster Complex‐Based Coordination Polymer as an Efficient Heterogeneous Catalyst in the Suzuki–Miyaura Coupling Reaction

“…Interestingly, whereas compound 1 exhibited the 3d photoelectron spectrum characteristic for a Mo II species (Figure , B), coordination polymer 2 displayed additional positively shifted peaks that were attributed to a Mo VI species (28 %), suggesting partial oxidation of the cluster core. Similar behavior, as observed for [Mo 6 I 8 L 6 ] 2– cluster complexes that were grafted to silicon or amorphous carbon surfaces, was tentatively attributed to the effect of the X‐ray beam , . The binding energies of the Pd 3d and Mo 3d lines are summarized in Table S2 (in the Supporting Information).…”

Hexamolybdenum Clusters Supported on Exfoliated h-BN Nanosheets for Photocatalytic Water Purification

“…After cluster deposition, the BNNS composition remains unchanged; however, as expected, the survey spectrum shows the appearance of new cluster-related peaks, namely, Mo 3d 3/2 (232.5 eV), Mo 3d 5/2 (229.2 eV), I 3d 3/2 (632.5 eV), and I 3d 5/2 (621 eV), which proves composite formation (typical spectra of the composites are shown in Figures and S9). The molybdenum and iodine peak positions correlate perfectly with literature data for octahedral molybdenum iodide clusters and cluster-containing materials. , Figure D demonstrates two additional shoulders at lower binding energies (619.5 and 630.8 eV) near the main peaks of the inner iodine ligands (I i ), which correspond to some unreacted apical ligands (I a ). This fact indicates that not all apical iodine ligands were replaced by NO 3 – during the cluster precursor preparation.…”

“…The molybdenum and iodine peak positions correlate perfectly with literature data for octahedral molybdenum iodide clusters and cluster-containing materials. 55,56 Figure 5D demonstrates two additional shoulders at lower binding energies (619.5 and 630.8 eV) near the main peaks of the inner iodine ligands (I i ), which correspond to some unreacted apical ligands (I a ). This fact indicates that not all apical iodine ligands were replaced by NO 3 − during the cluster precursor preparation.…”

From Cs2Mo6Cl14 to Cs2Mo6Cl14·H2O and Vice Versa: Crystal Chemistry Investigations

“…Face-capped Mo 6 X i 8 X a 6 units containing octahedral molybdenum clusters are the basic buildings blocks of many inorganic solid state compounds, hybrid frameworks and nanomaterials [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Formation of Mo 6 cluster occurs at high temperatures via solid state reactions.…”