Cycloplatination of Thiosemicarbazones Derived from Furane. Crystal and Molecular Structure of [{Pt[(OC4H2)C(Me)=NN=C(S)NHEt]}2{μ‐Ph2P(CH2)2PPh2}]

Treatment of thiosemicarbazones (OC4H3)C(Me)=NN(H)C(=S)NHR (R: Me, a; Et, b) with [cis-PtMe2(cod)] afforded the tetranuclear compounds [Pt{(OC4H2)C(Me)=NN=C(S)NHR}]4 (R: Me, 1a; Et, 1b). The reaction of 1a and 1b with triphenylphosphine in 1:4 molar ratio gave rise to the mononuclear compounds [Pt{(OC4H2)C(Me)=NN=C(S)NHR}(PPh3)] (2a, 2b). Treatment of 1a and 1b with large-bite diphosphines Ph2P(CH2)nPPh2 (n = 2, dppe; n = 3, dppp; n = 4, dppb) afforded the dinuclear compounds -[{Pt[(OC4H2)C(Me)=NN=C(S)NHR]}2{μ-Ph2P(CH2)nPPh2}], (3a–5a, 3b–5b), with the diphosphine in a bridging mode. Similar reactions with the short-bite diphosphines Ph2PCH2PPh2 (dppm) and Ph2PC(=CH2)PPh2 (vdpp) yielded the mononuclear compounds [Pt{(OC4H2)C(Me)=NN=C(S)NHR}-(Ph2PCH2PPh2-P)] (6a, 6b) and [Pt{(OC4H2)C(Me)=NN=C(S)NHR}(Ph2P-C(=CH2)PPh2-P)] (7a, 7b) with the diphosphine in a monodentate coordination. Treatment of 1a and 1b with [W(CO)5(Ph2CH2PPh2)] gave the novel heterodinuclear species [{Pt[(OC4H2)C(Me)=NN=C(S)NHR]}{W(CO)5(Ph2CH2PPh2-P)}] (8a, 8b), which could also be synthesized by reaction of 6a and 6b with [W(CO)5(THF)]. 1H, 31P-{1H} and 13C-{1H} NMR and IR data are given. The crystal structure of compound 3b has been determined by X-ray crystallography.