Facile synthesis of mononuclear early transition-metal complexes of κ³cyclo-tetrametaphosphate ([P₄O₁₂]⁴⁻) and cyclo-trimetaphosphate ([P₃O₉]³⁻)

Abstract

We herein report the preparation of several mononuclear-metaphosphate complexes using simple techniques and mild conditions with yields ranging from 56% to 78%. Treatment of cyclo-tetrametaphosphate ([TBA]4[P4O12]·5H2O, TBA = tetra-n-butylammonium) with various metal sources including (CH3CN)3Mo(CO)3, (CH3CN)2Mo(CO)2(η(3)-C3H5)Cl, MoO2Cl2(OSMe2)2, and VOF3, leads to the clean and rapid formation of [TBA]4[(P4O12)Mo(CO)3]·2H2O, [TBA]3[(P4O12)Mo(CO)2(η(3)-C3H5)], [TBA]3[(P4O12)MoO2Cl] and [TBA]3[(P4O12)VOF2]·Et2O salts in isolated yields of 69, 56, 68, and 56% respectively. NMR spectroscopy, NMR simulations and single crystal X-ray studies reveal that the [P4O12](4-) anion behaves as a tridentate ligand wherein one of the metaphosphate groups is not directly bound to the metal. cyclo-Trimetaphosphate-metal complexes were prepared using a similar procedure i.e., treatment of [PPN]3[P3O9]·H2O (PPN = bis(triphenylphosphine)iminium) with the metal sources (CH3CN)2Mo(CO)2(η(3)-C3H5)Cl, MoO2Cl2(OSMe2)2, MoOCl3, VOF3, WOCl4, and WO2Cl2(CH3CN)2 to produce the corresponding salts, [PPN]2[(P3O9)Mo(CO)2(η(3)-C3H5)], [PPN]2[(P3O9)MoO2Cl], [PPN]2[(P3O9)MoOCl2], [PPN]2[(P3O9)VOF2]·2CH2Cl2, and [PPN]2[(P3O9)WO2Cl] in isolated yields of 78, 56, 75, 59, and 77% respectively. NMR spectroscopy, NMR simulations and single-crystal X-ray studies indicate that the trianionic ligand [P3O9](3-) in these complexes also has κ(3) connectivity.

Synthesis, Characterization, and Electrochemical Analyses of Vanadocene Tetrametaphosphate and Phosphinate Derivatives

“…The V(1)–O(1) bond length (2.043(2) Å) is similar to reported single bonds . While most vanadium phosphates contain bridging phosphates, 2 is a rare example of a monomeric vanadium phosphate with a V:P ratio of 1:1. ,,− The magnetic moment of 2 was determined using the Evans method (μ eff = 2.90 μ B ) and, similarly to 1 , is consistent with a high-spin V III center. , The paramagnetic nature of 2 resulted in absent 1 H NMR signals for the Cp ring protons and broadened resonances for the phenyl ring protons. Complex 2 was indefinitely stable on storage in the glovebox at −40 °C but is unstable in solution at room temperature, as decomposition is observed after several days.…”

“…While several heterogeneous and homogeneous VPO model complexes have been synthesized in order to elucidate the reaction mechanism, − the vast majority of these contain vanadyl (VO) linkages, hindering the ability to distinguish VO from terminal PO bond reactivity (Scheme c). ,− In the cases where VO is absent, bimetallic species bridged by −OPR 2 O– linkers dominate, with very few having terminal PO bonds present . In order to probe possible new C–H bond functionalization pathways, such as the proposed ROA mechanism, new VPO model complexes are needed containing terminal PO linkages bound to encapsulated V centers.…”

Orthophosphate and Sulfate Utilization for C–E (E = P, S) Bond Formation via Trichlorosilyl Phosphide and Sulfide Anions

“…Such changes in chemical shift are diagnostic of trimetaphosphate coordinating as a ligand. , Diluting the reaction mixture in dichloromethane, thereby lowering the concentration of trichlorosilane and slowing the rate of reaction, led to the observation of an additional species ( 3 , Figure ), which by 31 P NMR spectroscopy was indicative of two trimetaphosphate units coordinated to two separate silicon centers. The connectivity of intermediate 3 was assigned based on the integration ratios and chemical shifts of the κ 3 coordinated (P a ), ultraphosphate (P b ), and branched (P c ) polyphosphate regions, as well as the coupling pattern (AB 2 , 2 J P–P = 27 Hz) of P b and P c . After 48 h, this intermediate had converted to one having a single 31 P NMR resonance at δ 29.4 ppm, which is formulated as [TBA] 2 [Si­(P 3 O 9 ) 2 ].…”

“…However, a small but significant shift (10 ppm) of the trimetaphosphate resonance in the 31 P NMR spectrum was observed when the initial reaction of [TBA] 3 [P 3 O 9 ]·2H 2 O with trichlorosilane was monitored at 23 °C. Such changes in chemical shift are diagnostic of trimetaphosphate coordinating as a ligand. , Diluting the reaction mixture in dichloromethane, thereby lowering the concentration of trichlorosilane and slowing the rate of reaction, led to the observation of an additional species ( 3 , Figure ), which by 31 P NMR spectroscopy was indicative of two trimetaphosphate units coordinated to two separate silicon centers. The connectivity of intermediate 3 was assigned based on the integration ratios and chemical shifts of the κ 3 coordinated (P a ), ultraphosphate (P b ), and branched (P c ) polyphosphate regions, as well as the coupling pattern (AB 2 , 2 J P–P = 27 Hz) of P b and P c .…”

Enhancing the inhibition and adsorption performance of SABIC iron corrosion in sulfuric acid by expired vitamins. Experimental and computational approach

“…41 It is worth mentioning that stability of complexes having chelate rings is much more than that of complexes containing none or fewer chelate rings owing to the chelate effect. 60,61 Therefore, one can expect the following for expired VB1: there are two possible coordination sites for iron as shown in Scheme 1A. For the rst coordination site, iron will prefer to coordinate to the two nitrogen atoms of the amino and imine groups of the VB1 due to the chelate effect; the coordinated iron atom will complete its coordination sphere with 4H 2 O molecules since this is occurring in the aqueous media.…”