Electrospray mass spectrometry (ESMS) provides a rapid and convenient technique for probing the nucleophilicity of the {Pt₂S₂} “butterfly” core. Positive-ion electrospray mass spectra have been recorded for a wide array of aggregates incorporating various metallo-fragments into the Pt₂(PPh₃)₄(μ-S)₂1 moiety. Such combinatorial-like screening allowed a large number of different metal–sulfur interactions to be studied and the resultant heterometallic aggregates postulated. Such postulations were subsequently confirmed by synthetic studies and single-crystal X-ray crystallographic analyses. This approach helped to minimize the “wastage” by focusing on the synthesis of aggregates that were supported by the ESMS evidence. It has resulted in the isolation of a series of novel aggregates such as {Au^IIIPt₂S₂}, {Hg^IIPt₂S₂}, and {Sn^IVPt₂S₂} in good lab-scale yields. It also led to the trapping and characterization of the monoprotonated product of 1, which has eluded isolation.

A series of mixed-ligand thiosalicylate complexes of the type [M(SC₆H₄CO ₂)(PPh₃)L] (M = Pt, L = pyridine (py), 4-methylpyridine, imidazole, 4-picolinic acid hydrazide {C₅H₄N[C(O)NHNH₂]-4}; M = Pd, L = pyridine) have been prepared by the one-pot reaction of [PtCl₂(cod)] or [PdCl₂(cod)] (cod = cycloocta-1,5-diene) with one equivalent of PPh₃ and thiosalicylic acid (HSC₆H₄CO₂H) in the presence of the nitrogen base. Single-crystal X-ray diffraction studies on [Pt(SC₆H₄CO ₂)(PPh₃)(py)] and the previously reported complex [Pt(SC₆H₄CO ₂)(PPh₃)(XyNC)] (Xy = 2,6-xylyl) indicates that the complexes have different geometries, though in each case the two ligands of highest trans-influence are mutually cis. The reaction of [PtCl₂(cod)] with PPh₃, thiosalicylic acid and ammonia led to the isolation of crystals of the dinuclear thiosalicylate-bridged complex [Pt(SC₆H₄CO ₂)(PPh₃)(NH₃)Pt(SC₆H₄CO ₂)(PPh₃)], which was characterised by X-ray crystallography and electrospray mass spectrometry. The conformation of the thiosalicylate ligand can vary widely with values for the dihedral angle between the ligand plane and the platinum(II) coordination plane varying from 12.4° to 70.9° in the seven complexes so far determined. The biological activities of selected platinum and palladium thiosalicylate and related complexes against P388 leukemia cells, bacteria and fungi are also reported. The complex [Pt(SCH₂CO ₂)(PPh₃)₂] shows the highest activity against P388 cells (IC₅₀ 671 ng mL⁻¹).

Electrospray Mass Spectrometry (ESMS) has been used as a tool to probe the reactivity of the metalloligand [Pt₂(μ-Se)₂(PPh₃)₄] with metal substrates, which lead to the formation of charged coordination complexes via loss of halides or other labile ligands. Among the numerous metal substrates used in the displacement reactions are Au(anpy)Cl₂ (anpy = cyclometallated 2-anilinopyridyl), HgPhCl and Pb(NO₃)₂. Acid titration on the Lewis basic metalloligand leads to the identification and isolation of the doubly-protonated species, [Pt₂(μ-SeH)₂(PPh₃)₄]²⁺, whose sulfide analogue cannot be isolated. A three-step strategy is employed in the use of ESMS as a probe: (i) preliminary screening of the metalloligand with an array of acidic main group and transition group metal compounds, (ii) identification of potentially stable and isolable products formed in situ based on ion distribution and simulated isotope patterns and (iii) promising reactions are repeated on a laboratory scale, and target products are isolated and characterized. X-Ray diffraction studies have been performed on single crystals of [Pt₂(μ-SeH)₂(PPh₃)₄][ClO₄]₂, [Pt₂(μ₃-Se)₂(PPh₃)₄(CdCl₂)] and {Pt₂(μ₃-Se)₂(PPh₃)₄[Pb(NO₃)]}{NO₃}. These results suggested that in general a parallel chemistry can be developed on the intermetallic selenides as on the sulfides. However, there are chemical and structural differences which are highlighted in this paper.