Peptide-Functionalized Organotin Sulfide Clusters

We report the first successful attachment of peptides to tin sulfide clusters. For proof of principle, H-l-Phe hydrazide and Boc-protected dipeptide hydrazides (Boc-l-Ala-l-Ala hydrazide and Boc-l-Val-l-Phe hydrazide) were reacted with keto-functionalized tin sulfide clusters [(R1Sn)4S6] (A; R1 = CMe2CH2C­(O)­Me) and [(R1Sn)3S4Cl] (B). In the first case, we obtained single crystals of an amino acid functionalized Sn/S cluster, [R22Sn4S5] (1; R2 = (CMe2CH2C­(Me)­N2C­(O)­CH­(CH2Ph)­NC­(Me)­CH2CMe2), formed after inorganic cluster rearrangement and intramolecular condensation of the amino acid ligand. By means of NMR spectroscopic investigations and ESI/LIFDI mass spectrometry, we demonstrate that both dipeptides are attached to B under retention of the original cluster architecture to yield [(R3Sn)3S4Cl] (2; R3 = CMe2CH2C­(NNH-Ala-Ala-Boc)­Me) and [(R4Sn)3S4Cl] (3; R4 = CMe2CH2C­(NNH-Phe-Val-Boc)­Me), as evident from mass spectrometric data of their cations [(R3Sn)3S4]+ (2+) and [(R4Sn)3S4]+ (3+).