What are oxidation numbers of each element in CuH?

My chemistry teacher said hydrogen when bonded with metals has oxidation number (O.N.) of −1 *except* CuH: in CuH the hydrogen has O.N. +1 and the copper has O.N. −1.


But on the internet it is ubiquitously told that the O.N. of hydrogen is −1 in CuH too, and the compound's name is [copper(I) hydride](https://en.wikipedia.org/wiki/Copper_hydride). I am confused which one is correct. If hydrogen has O.N. of +1 in CuH, why is it so?




Korzhavi and Johanssen [1](https://www.researchgate.net/publication/267401061_Svensk_Karnbranslehantering_AB_Thermodynamic_properties_of_copper_compounds_with_oxygen_and_hydrogen_from_first_principles) performed first-principles calculations on the electronic energy levels of several compounds of copper, hydrogen and oxygen. They find good agreement between derived and experimental properties of stable compounds such as $\ce{Cu2O}$ and correctly predict the instability of other candidate compounds such as $\ce{CuOH}$ and $\ce{CuH2}$.


For $\ce{CuH}$ the calculated density of electron states shows the hydrogen-based 1s states filled, and lower in energy than the copper-based 3d states. This is similar to the oxygen- and hydroxyl-based states in the oxide and hydroxide. The copper hydride result thereby identifies that compound as a metal hydride with positive metal oxidation state.


[![enter image description here](https://i.stack.imgur.com/9jTLd.png)](https://i.stack.imgur.com/9jTLd.png)


**Reference**


1. Korzhavyi, Pavel & Johansson, Borje. "Thermodynamic properties of copper compounds with oxygen and hydrogen from first principles." Report to Svensk Kärnbränslehantering AB, Texhnical Report TR-10-30, February 2010. Retrieved 19 June 2022.


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