N-tert-butoxycarbonyl (BOC) protected [V₆O₁₃{(OCH₂)₃CNH₂}₂]²⁻: synthesis, structural characterization, and solution behavior

Abstract

Herein, we report the synthesis of N-tert-butoxycarbonyl (BOC) protected [V 6 O 13 {(OCH 2) 3 C-NH 2 } 2 ] 2built from the Lindqvist-type hexavanadate. The reaction of di-tert-butyl dicarbonate (BOC 2 O) with tris(hydroxymethyl)aminomethane (Tris) led to the organic derivative [(OCH 2) 3 C-NH(BOC)] that reacts with the decavanadate in dimethylacetamide (DMA) to form the [V 6 O 13 {(OCH 2) 3 C-NH(BOC)} 2 ] 2anions. The tetrabutylammonium (TBA +) salt of this hybrid polyoxovanadate, TBA 2 [V 6 O 13 {(OCH 2) 3 C-NH(BOC)} 2 ]•2DMA, has been characterized in the solid-state by single crystal X-ray diffraction and infrared spectroscopy, and in solution by multinuclear (1 H, 13 C and 51 V) and DOSY NMR, and UV-visible spectroscopy.

Versatile post-functionalisation strategy for the formation of modular organic–inorganic polyoxometalate hybrids

“…The 13 C NMR spectrum showed a similar break in the symmetry of dP, with peaks at 85.94 and 63.10 ppm assigned to the V-O-CH 2 -and -CH 2 -OH carbons respectively, and two peaks observed at 73.21 and 71.79 ppm corresponding to the -CH 2 -O-CH 2 -carbons. The formation of the V 6 POM core was also confirmed by the presence of a single sharp peak at -497 ppm in the 51 V NMR spectrum (Figure S6), which is typical of trans-functionalised hexavanadates, 45,46 as well as by the characteristic peaks in the IR spectrum (Figure S10) at 953 (ν V=O, vs), 810 (ν V-O-V, s), 791(ν V-O-V, s), and 709 (ν V-O-V, vs) cm -1 . 47 Due to the paramagnetic nature of Cr 3+ , C could not be fully characterised by 1 H NMR as very broad peaks were obtained (Figure S8).…”

“…The formation of the V 6 POM core was also conrmed by the presence of a single sharp peak at À497 ppm in the 51 V NMR spectrum (Fig. S6 †), which is typical of transfunctionalised hexavanadates, 45,46 as well as by the characteristic peaks in the IR spectrum (Fig. S10 †) at 953 (n V]O, vs.), 810 (n V-O-V, s), 791 (n V-O-V, s), and 709 (n V-O-V, vs.) cm À1 .…”

“…In the 1 H NMR spectrum, the V-O-CH 2protons attached to the POM are highly deshielded, giving rise to a peak at 5.04 ppm, while a peak at 3.46 ppm was observed for the free -CH 2 -OH ethyl protons as expected for POM-bound and free -OCH 2groups. 44,45 Similarly, the peak due to the bridging -CH 2 -O-CH 2ether group was split into two peaks at 3.31 and 3.29 ppm due to the formation of the functionalised POM. The 13 C NMR spectrum showed a similar break in the symmetry of dP, with peaks at 85.94 and 63.10 ppm assigned to the V-O-CH 2and -CH 2 -OH carbons respectively, and two peaks observed at 73.21 and 71.79 ppm corresponding to the -CH 2 -O-CH 2carbons.…”

Versatile Post-functionalisation Strategy for the Formation of Modular Organic-Inorganic Polyoxometalate Hybrids

“…The 13 C NMR spectrum showed a similar break in the symmetry of dP, with peaks at 85.94 and 63.10 ppm assigned to the V-O-CH2-and -CH2-OH carbons respectively, and two peaks observed at 73.21 and 71.79 ppm corresponding to the -CH2-O-CH2-carbons. The formation of the V6 POM core was also confirmed by the presence of a single sharp peak at -497 ppm in the 51 V NMR spectrum (Figure S6), which is typical of trans-functionalised hexavanadates, 45,46 as well as by the characteristic peaks in the IR spectrum (Figure S10) at 953 (ν V=O, vs), 810 (ν V-O-V, s), 791(ν V-O-V, s), and 709 (ν V-O-V, vs) cm -1 . 47 Due to the paramagnetic nature of Cr 3+ , C could not be fully characterised by 1 H NMR as very broad peaks were obtained (Figure S8).…”

“…In the 1 H NMR spectrum, the V-O-CH2-protons attached to the POM are highly deshielded, giving rise to a peak at 5.04 ppm, while a peak at 3.46 ppm was observed for the free -CH2-OH ethyl protons as expected for POM-bound and free -OCH2-groups. 44,45 Similarly, the peak due to the bridging -CH2-O-CH2-ether group was split into two peaks at 3.31 and 3.29 ppm due to the formation of the functionalised POM. The 13 C NMR spectrum showed a similar break in the symmetry of dP, with peaks at 85.94 and 63.10 ppm assigned to the V-O-CH2-and -CH2-OH carbons respectively, and two peaks observed at 73.21 and 71.79 ppm corresponding to the -CH2-O-CH2-carbons.…”