Facile Access to Homo‐ and Heteroleptic, Triply Bonded Dimolybdenum Hexaalkoxides with Unsaturated Alkoxide Ligands

Abstract

A series of monodentate, triply bonded Mo 2 (OR) 6 complexes [R = MBE (1) (MBE = 2-methylbut-3-ene-2-yl), MMP (2) (MMP = 1-methoxy-2-methylpropane-2-yl), Terp (3) [Terp = 2-(4-methylcyclohex-3-enyl)propane-2-yl], which exhibit C-C double bonds or an ether function in the ligand sphere, were synthesized and characterized by multinuclear ( 1 H, 13 C and 95 Mo) NMR studies. The partial alcoholysis of the latter complexes with neopentyl alcohol (neopentOH) led to the heteroleptic alkoxides Mo 2 (OR) n (Oneopent) 6-n (4-7) {n = 2 [for R = tBu (4), MBE (5), MMP (6)], 4 [for R = Terp (7)]}. This concept was further applied to the synthesis of Mo 2 (O 2 DMH) 2 -(OtBu) 2 (8) (DMH = 2,5 dimethylhexyl) by starting from the Mo 2 (OtBu) 6 precursor. The 1 H NMR spectra for the heteroleptic complexes 4-8 show signals that are significantly shifted to a higher field for the RO ligand protons compared to those of their homoleptic analogues. This is the result of a change in the spatial position of the alkoxide ligands (RO) in the homoleptic compared to the heteroleptic complexes that

Intermolecular Hydrogen–Fluorine Interaction in Dimolybdenum Triply Bonded Complexes Modified by Fluorinated Formamidine Ligands for the Construction of 2D‐ and 3D‐Networks

“…[11] The strong shift to a lower field of the methine proton (N=CH-N) can also be attributed to the diamagnetic anisotropy, since it is placed over the centre of the triple bond and thus strongly deshielded. [12] In both the 1 H NMR and the 13 C NMR spectra we observed only one set of broad signals for both of the aryl ligands on the same formamidine. This implied a symmetrical bonding contribution for both of the nitrogen atoms.…”

“…Undoubtedly, triplybonded molybdenum complexes are of interest because of their applicability as precursor for heterogeneous materials [10] and as precursor for heterobimetallic compounds, [11] which makes them profitable systems for further applications. Recently, some of us synthesized monodentate MoϵMo alkoxides, [11,12] which exhibit the general motif of an "ethane-like" structure with a staggered ligand conformation and unequally oriented ligands with different Mo···O distances at each of the molybdenum atoms. [13] Based on these types of complexes we were interested in the coordination abilities of the formamidine ligands.…”

Low‐Valent Molybdenum‐Based Dual Pre‐Catalysts for Highly Efficient Catalytic Epoxidation of Alkenes and Deoxygenation of Sulfoxides

“…Accordingly, the previously reported [12] homoleptic alkoxides [Mo 2 (OR) 6 ] (1-6) and heteroleptic alkoxides [Mo 2 (OR) 4 (OR') 2 ] (7-9) (Scheme 1) were probed for two "antagonistic" catalytic reactions: 1) epoxidation of olefins with tert-butyl hydroperoxide (TBHP), and 2) deoxygenation of diorganosulfoxides by silanes to give the corresponding sulfides. On the one hand, they allow a selective oxidation, adjustable to the catalytic conditions, of the Mo III sites.…”

“…Intriguingly, many reduction reactions are performed by molybdenum-based enzymes, which underline the high versatility of this metal. [11][12][13] This type of complex is well-known and established, which is a result of the seminal work by Cotton, Chisholm, and co-workers. [6] These enzymes efficiently catalyze the deoxygenation of sulfoxides and they have been intensively investigated for their structural properties and their catalytic applicability; even some model systems mimicking their active centre have been synthesized.…”

“…[20] The variety of applied catalysts is immensely broad, including [MoO 2 (acetylacetonate) 2 ] and [Mo(CO) 6 ] , [21] heteropoly anions [PMo 12 O 40 ] 3À , [22] and even metallic molybdenum. [20] The variety of applied catalysts is immensely broad, including [MoO 2 (acetylacetonate) 2 ] and [Mo(CO) 6 ] , [21] heteropoly anions [PMo 12 O 40 ] 3À , [22] and even metallic molybdenum.…”