This file contains all reviewer reports in order by version, followed by all author rebuttals in order by version.

Version 0:
Reviewer comments:
Reviewer #1
(Remarks to the Author)
The manuscript entitled “An Exceedingly Low-Coordinate Platinum(0)-Germylene for E–H Bond Activation and Catalytic Hydrodehalogenation” by Jesús Campos describes the E‒H bond activation facilitated by Platinum(0)-Germylene cooperation, resulting in the formation of Pt(II)-germyl compounds. The Pt/Ge complex 1 reacts with alkynes to form 1,2platinogermacyclobutadiene compounds (compound 7), which also serve as efficient catalysts in hydrodehalogenation reactions. The structural symmetry of these compounds has been analyzed using NMR, X-ray single crystal data, and computational studies. Overall, the chemistry is well-executed and well-described, with some improvements suggested below. I am pleased to support its acceptance in this journal.

General Comments:
Compound 1 has successfully catalyzed the dehalogenation reaction. Can the stoichiometric reaction product of 1 with aliphatic or aromatic halides be obtained? This might help in understanding the reaction mechanism better. The authors have investigated the catalytic potential of compound 1 in the hydrodehalogenation of aliphatic and aromatic halides. What about the hydrodefluorination of organic fluorides? All yields of reactions are reported in spectroscopic form and were performed at room temperature. Can the authors attempt to separate and purify the products at low temperature to confirm the actual isolation yield of each reaction? Page 4, Line 9: “consistent with reactivity studies …” needs correction. Page 6, Figure 4: States 5 equivalents of methanol. Supplementary Information S7, Compound 4: States 2 equivalents and 1 equivalent of methanol. The authors need further confirmation and correction. Page 5, Line 10: “[ArDippGeCl]2 reacts with water, methanol, and ammonia to yield mixtures of products.” The structural information of these mixtures is not provided. Page 8, Line 12: The structural formula “κ1 interaction” of compound 3 is not consistent with “the π-interaction with the flanking aryl ring is now closer to a κ2-coordination”. Page 12, Figure 9: Change “RCCH” on the arrow to “2 RCCH”.


Reviewer #2
(Remarks to the Author)
The manuscript by Campos and colleagues describes an intriguing Pt germylene species (1) which was prepared by substitution of tBu-ethylene with a germylene source (a germylene dimer). Unfortunately, complex 1 is thermally unstable, and accordingly, was not isolated as an analytically pure material, nor was it characterized by X-ray crystallography. When generated in situ, complex 1 reacts with bonds in various small molecules (including the N-H of NH3). The authors refer to this as "cooperative activation", though addition of bonds across metal-main group multiple bonds is well known and usually not described as cooperative activation. Related work by Tilley (e.g. Organometallics 2009 5082) was not referenced. Complex 1 also inserts alkynes into the Pt=Ge bond. While these complexes and related reaction chemistry are interesting, they are not particularly novel. The highest impact of this work, in my opinion, is the catalytic dehydrohalogenation, particularly the fact that alkyl substrates were used. In addition, chlorides worked reasonably well. The manuscript would benefit from additional computational work to elucidate the mechanism of the catalytic cycle. If that were included, I would support publication of this manuscript in Nature Chemistry. One final comment: the authors refer to complex 1 as "exceedingly low coordinate". Given that no X-ray crystal structure was obtained, and the aryl groups on both the P and Gemight interact with the metal centre, this is perhaps somewhat of an over-reach. Why not simply call it "low coordinate"?

Reviewer #3
(Remarks to the Author)
This manuscript by Campos and coworkers deals with a Pt(0)-germylene complex. It is coordinately unsaturated at both Pt and Ge, which makes it proned to E-H bond activation. H2, H2O, MeOH and NH3 are shown to readily add across the formal Pt=Ge linkage. Catalytic hydrodehalogenation is also reported, with both alkyl and aryl substrates. This is a very important and original piece of work. Small molecule activation by transition metal / main group compounds has several precedents and is no longer a big surprise, but applying such systems to synthetically useful catalytic transformations is rare and remarkable. All the more so that the Pt(0)-germylene complex works with alkyl and aryl substrates with H2 as reductant. The manuscript is pleasant to read, the work is of high scientific and technic quality. All compounds have been fully characterized. I for sure recommend publication of this work in Nature Communications but there is one point that requires consideration and should be addressed before publication. It is the link between the stoechiometric studies of E-H bond activation and the catalytic hydrodehalogenation. I agree with the authors that « a thorough mechanistic picture lies out of the scope of the present contribution », but the relevance of the cooperative activation of H2 by the Pt(0)-germylene complex to the catalytic transformation should be substantiated. All the more so that the authors point some observations suggesting the involvement of radical pathways. It would also be nice to extend the stoechiometric studies to the RX substrates as some of them may compete with H2 upon reaction with the Pt(0)-germylene complex. Minor corrections : - Some phrasings are inappropriate and require polishing. For example on page 4 : « … suggesting that this atom partly retains its Z-type character ». - I also recommend careful proofreading. I noticed several typos.

Version 1:

Reviewer comments:
Reviewer #1 (Remarks to the Author) The authors have systematically introduced the E‒H bond activation and catalytic hydrodehalogenation applications of lowcoordinate platinum(0)-germylene, elucidating the catalytic reaction mechanism through detailed experimental and theoretical calculations. The authors have also addressed my questions regarding this work, and the manuscript has been thoroughly revised and is now suitable for acceptance.
Reviewer #2 (Remarks to the Author) After carefully scrutinizing the revised version of the manuscript by Campos and colleagues, as well as the responses to all reviewer comments, I fully endorse its publication in Nature Communications. Every single comment was addressed in depth and a great deal of additional work was performed. The result is substantial improvement to an already excellent contribution.

Reviewer #3 (Remarks to the Author) The authors have carefully revised their manuscript. They have taken into account and convincingly addressed all the comments raised by the reviewers. In my opinion, the paper can be published in Nature Communications as is., Pairing transition metals and heavier tetrylenes (Si, Ge, Sn, Pb) holds great potential for cooperative bond activation and catalysis. In this work, we investigate the reactivity of a low-coordinate Pt(0)/Ge(II) system that emerges from the reaction between the monoligated platinum(0) precursor [(PMe2ArDipp2)Pt(olefin)] with germylene dimer [ArDipp2GeCl]2 (where ArDipp2 = C6H3-2,6-(C6H3-2,6-iPr2)2). The resulting complex reveals ability for cooperative bond activation. Stoichiometric reactions with dihydrogen, water, methanol, ammonia and alkynes unveil the formation of Pt(II)-germyl compounds, characterized by distinct isomeric forms, whose flexibility derives from the particularly low-coordination. We explore its catalytic potential in the hydrodehalogenation of aliphatic, aromatic and main-group halides under dihydrogen atmosphere using both thermal and photochemical conditions, demonstrating promising conversions even for more challenging alkyl chlorides.
Pairing transition metals and heavier tetrylenes holds potential for cooperative bond activation. Here, the authors investigate the reactivity of a low-coordinate Pt(0)/Ge(II) system that emerges from the reaction between a monoligated platinum(0) precursor with a germylene dimer and explore its application as a hydrodehalogenation catalyst., This work has been supported by the European Research Council (ERC Starting Grant, CoopCat, 756575; JC), the Spanish Ministry of Science and Innovation (PID2022-139782NB-I00; JC, and TED2021-132225B-I00; JC) and Junta de Andalucia (P18-FR-4688; JC). We also acknowledge the European Commission for a MSCA fellowship (101023461; SB), and the use of computational resources of the CSIRC of the Universidad de Granada -cluster Albaicín-. We thank Lamin Keita for his assistance on ligand and precursor synthesis., Peer reviewed

As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors., Using single-crystal to single-crystal solid/gas reactivity the gold(I) acetylene complex [Au(L1)(eta 2-HC equivalent to CH)][BArF4] is cleanly synthesized by addition of acetylene gas to single crystals of [Au(L1)(CO)][BArF4] [L1=tris-2-(4,4 '-di-tert-butylbiphenyl)phosphine, ArF=3,5-(CF3)2C6H3]. This simplest gold-alkyne complex has been characterized by single crystal X-ray diffraction, solution and solid-state NMR spectroscopy and periodic DFT. Bonding of HC equivalent to CH with [Au(L1)]+ comprises both sigma-donation and pi-backdonation with additional dispersion interactions within the cavity-shaped phosphine.

The existence of pi-acetylene gold(I) compounds as intermediates in catalysis has been postulated, but their isolation or spectroscopic detection has remained elusive. Herein, the combination of a bulky cavity-shaped phosphine along with single-crystal to single-crystal reactivity allowed for the isolation of the first gold(I)-acetylene complex, which was thoroughly characterized by X-ray diffraction, solution and solid-state NMR, periodic DFT, and electronic structure analyses. image, This work was supported by the European Research Council (ERC Starting Grant, CoopCat, Project 756575) and the Spanish Ministry of Science and Innovation (PID2022-139782NB-I00). M. N. acknowledges the Spanish Ministry of Science and Innovation and Junta de Andalucía for postdoctoral programs (FJC2018-035514-I and DOC_00149). Leverhulme Trust (RPG-2020-184; MRG, CLJ) and the Wild Overseas Scholar's Fund (CLJ); the University of St. Andrews (DJS) and EPSRC (EP/W015498/1, MAS; UK Catalysis Hub, EP/R026815/1, MRG). Dr A. Whitwood (York) for helpul discussions and Dr V. Annis (York) for technical assistance with 13C-acetylene experiments., Peer reviewed

- "Compound schemes" pdf including the chemical structures of the compounds included in the dataset.
- Folder for Nuclear Magnetic Resonance (NMR) experiments: full characterization of all the compounds reported in the manuscript, from 1-8 and 3'., NMR experiments were carried out using NMR tubes adapted with J-Young valves. NMR spectra were recorded on Solution NMR spectra were recorded with Bruker AVANCE NEO-300, AVANCE NEO-400, AVANCE III-400, and AVANCE NEO-500 spectrometers. Spectra were referenced to external SiMe4 (δ: 0 ppm) by using the residual proton solvent peaks as internal standards (1H NMR experiments), or the characteristic resonances of the solvent nuclei (13C NMR experiments), while 31P was referenced to H3PO4., ERC Consolidator Grant, BiMetalGAS, 101169746
Spanish Ministry of Science, Innovation and Universities: PID2022-139782NB-I00/AEI/10.13039/501100011033/ FEDER, UE
Fundación La Caixa fellowship (ID 100010434; fellowship code B005930, A.P.-M.), Peer reviewed

[Description of methods used for collection/generation of data] NMR experiments were carried out using NMR tubes adapted with J-Young valves. NMR spectra were recorded on Solution NMR spectra were recorded with Bruker AVANCE NEO-300, AVANCE NEO-400, AVANCE III-400, and AVANCE NEO-500 spectrometers. Spectra were referenced to external SiMe4 (δ: 0 ppm) by using the residual proton solvent peaks as internal standards (1H NMR experiments), or the characteristic resonances of the solvent nuclei (13C NMR experiments), while 31P was referenced to H3PO4., [Methods for processing the data] NMR data can be opened with MestreNova or Bruker Topspin software packages., This dataset contains raw data for article: "Cooperative C–Cl Bond Activation of Dichloromethane by Heterobimetallic Ir(I)–M(IV) Pairs (M = Mo, W)" by Martina Landrini, Emmanuel Serrano-Díez, Luca Rocchigiani y Jesús Campos, to be published in as a flash communication in Organometallics in 2026. It includes the following files and folders:
- "Compound schemes" pdf including the chemical structures of the compounds included in the dataset.
- Folder for Nuclear Magnetic Resonance (NMR) experiments: full characterization of all new compounds (4 and 5) and reactivity studies., - ERC Consolidator Grant, BiMetalGAS, 101169746;
- Grant PID2022-139782NB-I00/AEI/10.13039/501100011033/ FEDER, UE
- Royal Society of Chemistry (R22-0875640255);
- European Union Next Generation EU under the Italian Ministry of University and Research (MUR) National Innovation Ecosystem grant ECS00000041-VITALITY;, File List: - "Compound schemes" pdf including the chemical structures of the compounds included in the dataset. - NMR: Characterization of compounds 4 and 5 and NMR analysis of the various reactivity experiments., Peer reviewed