Stoichiometric molecular single source precursors to cobalt phosphides

•We synthesise cobalt phosphides NPs from 3 different tetranuclear cobalt clusters.•We show that a slightly reducing atmosphere is required to get phosphides only.•[Co4(CO)10(μ-dppa) and [Co4(CO)10(μ4-PPh)2] lead to Co2P.•[Co4(CO)8(μ-dppa)2] lead to a mixture of CoP and Co2P.•The chemical nature of the phosphides is controlled but not the particle size.

Crystalline cobalt phosphides were synthesized by using three different, low oxidation-state organometallic clusters as precursors, [Co4(CO)10(μ-dppa)], [Co4(CO)10(μ4-PPh)2] and [Co4(CO)8(μ-dppa)2] (dppa = Ph2PNHPPh2), which are characterized by Co/P ratios of 2:1, 2:1 and 1:1, respectively. Depending on their Co/P ratio, these clusters are suitable single-source precursors to form CoP and Co2P without the need to add any other reagent or surfactant. The thermal behavior of these three clusters was investigated under different conditions. The results show how their Co/P ratios, the nature of the atmosphere used for their thermal activation and the temperature control the nature and composition of the resulting phases.

Graphical abstractSynthesis of crystalline cobalt phosphides NPs from three different tetranuclear cobalt clusters as single-source precursors, characterized by different metal to phosphorus ratios, namely Co/P = 2 in Co4(CO)10(μ-dppa) (1) and Co4(CO)10(μ4-PPh)2 (2), and Co/P = 1 in Co4(CO)8(μ-dppa)2 (3) (dppa = Ph2PNHPPh2) are reported. While two clusters (1, 2) with the appropriate stoichiometry led to Co2P only, the third cluster (3) gave a mixture of CoP and Co2P but an excess of phosphorus allows the formation of well faceted Co2P crystallites.Figure optionsDownload full-size imageDownload as PowerPoint slide