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The measurement of dipolar and J- couplings between 29 Si and 17 O isotopes is challenging owing to (i) the low abundance of both isotopes and (ii) their close Larmor frequencies, which only differ by 19%. These issues are circumvented here by the use of isotopic enrichment and dedicated triple-resonance magic-angle spinning NMR probe. The surface of 29 Si-enriched silica was labelled with 17 O isotope and heated at 80 and 200 °C. 29 Si- 17 O connectivities and proximities were probed using two-dimensional (2D) through-bond and through-space heteronuclear multiple-quantum coherences (J- and D-HMQC) experiments between 17 O and 29 Si nuclei. The simulation of the build-up of the J- and D-HMQC signals allowed the first experimental measurement of J- and dipolar coupling constants between 17 O and 29 Si nuclei. These HMQC experiments allow distinguishing two distinct siloxane (SiOSi) oxygen sites: (i) those covalently bonded to Q 3 and Q 4 groups, having a hydroxyl group as a second neighbour and (ii) those covalently bonded to two Q 4 groups. The measured J- and dipolar coupling constants of siloxane 17 O nucleus with Q 4 29 Si nuclei differ from those with Q 3 29 Si nuclei. These results indicate that the 29 Si- 17 O one-bond J-coupling and Si-O bond length depend on the second neighbours of the Si atoms., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Inc. All rights reserved.)