Reactions of trans-(C6F5)L2PtCl (2, L = Ph2P(CH2)4O(CH2)2CHCH2; 6, L = Ph2P(CH2)2C(CH3)2(CH2)3CHCH2) and H(CC)2H (HNEt2, cat. CuI) give trans-(C6F5)L2Pt(CC)2H (3, 7; 86–97%). Oxidative homocouplings (O2, cat. CuCl/TMEDA, acetone) yield trans,trans-(C6F5)L2Pt(CC)4PtL2(C6F5) (4, 8; 75–86%). Reactions with Grubbs’ catalyst, followed by hydrogenation, give mainly trans,trans-(C6F5)(Ph2P(CH2)4O(CH2)6O(CH2)4PPh2)Pt(CC)4Pt(Ph2P(CH2)4O(CH2)6O(CH2)4PPh2)(C6F5) (5), with termini-spanning diphosphines, and trans,trans-(C6F5)(Ph2P(CH2)2C(CH3)2(CH2)8C(CH3)2(CH2)2PPh2)Pt(CC)4Pt(Ph2P(CH2)2C(CH3)2(CH2)8C(CH3)2(CH2)2PPh2)(C6F5) (9), with trans-spanning diphosphines, respectively. Reactions of trans,trans-(C6F5)(p-tol3P)2Pt(CC)4Pt(Pp-tol3)2(C6F5) with Ph2P(CH2)2C(CH3)2(CH2)8C(CH3)2(CH2)2PPh2 and p-tol2P(CH2)3(CF2)8(CH2)3Pp-tol2 give 10 (70%), the isomer of 9 with termini-spanning diphosphines, and the analogous adduct of the fluorinated diphosphine. However, the latter oligomerizes upon attempted workup. The crystal structure of 5 shows that the sp3 chains adopt a chiral double-helical conformation about the sp chain, with the endgroups defining a 164.1° angle. Additional conformational properties of the preceding complexes are analyzed in detail, and dynamic properties are probed by low temperature NMR experiments.

Despite promising anti-cancer properties in vitro, all titanium-based pharmaceuticals have failed in vivo. Likewise, no target-specific positron emission tomography (PET) tracer based on the radionuclide ⁴⁵Ti has been developed, notwithstanding its excellent PET imaging properties. In this contribution, we present liquid–liquid extraction (LLE) in flow-based recovery and the purification of ⁴⁵Ti, computer-aided design, and the synthesis of a salan-^natTi/⁴⁵Ti-chelidamic acid (CA)-prostate-specific membrane antigen (PSMA) ligand containing the Glu-urea-Lys pharmacophore. The compound showed compromised serum stability, however, no visible PET signal from the PC3+ tumor was seen, while the ex vivo biodistribution measured the tumor accumulation at 1.1% ID/g. The in vivo instability was rationalized in terms of competitive citrate binding followed by Fe(III) transchelation. The strategy to improve the in vivo stability by implementing a unimolecular ligand design is presented.