1 “This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Catalysis, copyright © 2017 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/doi/abs/10.1021/acscatal.7b01860 Hydrogen Bonding Rescues Overpotential in Seven Coordinated Ru Water Oxidation Catalysts Roc Matheu, a,b Mehmed Z. Ertem, c Carolina Gimbert-Suriñach, a Jordi Benet-Buchholz, a Xavier Sala* ,d and Antoni Llobet* a,d a Institute of Chemical Research of Catalonia (ICIQ), Avinguda Països Catalans 16, 43007 Tarragona, Spain. b Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, Marcel·lí Domingo s/n, 43007 Tarragona, Spain. c Chemistry Division, Energy & Photon Sciences Directorate, Brookhaven National Laboratory, Upton, New York, 11973-5000, USA d Departament de Química, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, 08193 Barcelona, Spain. Corresponding authors: allobet@iciq.es; xavier.sala@uab.cat