Figure 1: 31P NMR spectra of CdSe reaction mixtures with Se precursor.

(a) 2Cd(OOCC17H33)2+SeTOP+HPPh2. (b) 2Cd(OOCC17H33)2+SeTOP+HPPh2+2C18H35NH2. (c) 2Cd(OOCC17H33)2+SeTOP+HPPh2+2C12H25SH. (d) 2Cd(OOCC17H33)2+SeTOP+HPPh2+2C12H25OH. The experiments were performed at RT for 15 (1), 30 (2) and 60 min (3). The peak denoted with an asterisk (*) is TOP complexed to Cd (ref. 23). Interestingly, the P-containing products detected from the four reactions can be grouped into two product types, Ph2P–Y (1) and Ph2P(Se)–Y (2). The slowest disappearance of SeTOP is with the use of amine, the trend of which is in agreement with our kinetics study (Supplementary Figs 28–31 and Supplementary Note 5) based on our putative pathway proposed (Fig. 6) and the consideration of constitutional isomers (Fig. 7).