High resolution mass spectra (HRMS) were acquired on a JEOL AccuTOF 4G LC-plus equipped with an ionSense DART (Direct Analysis in Real Time) source for phosphines 1 – 5. HRMS for complexes 1-Cu – 5-Cu were obtained on an Agilent 6545 mass spectrometer coupled to an Agilent Infinity 1260 LC system running a Jet Stream electrospray ionization (ESI) source.

DART(+) data may be processed using JEOL software (msAxel data processing). Performing drift compensation is required by referencing PEG(+) a 415.25377. A pdf guide is available at https://chemistry.mit.edu/facilities-and-centers/department-of-chemistry-instrumentation-facility-dcif/ and a local copy dated to 25 May 22 is available.

ESI(+) data may be processed using Agilent software (MassHunter Quanlitative Analysis).