Thermolysis of (tBu2PC2H4PtBu2)NiMe2 in benzene or reduction of (tBu2PC2H4PtBu2)NiCl2 with Mg* in THF/benzene affords a solution of mononuclear (tBu2PC2H4PtBu2)Ni(η2-C6H6) (1) and dinuclear {(tBu2PC2H4PtBu2)Ni}2(μ-η2:η2-C6H6) (2) in equilibrium. Complex 2 has been isolated; the X-ray structure analysis reveals an antifacial coordination of the [(tBu2PC2H4PtBu2)Ni0] moieties to adjacent CC bonds of a formal cyclohexatriene ligand. According to solid-state and solution NMR the structure of 2 is static in the solid and fluxional in solution. Displacement of the benzene ligand in 1 or 2 by C6F6 affords mononuclear (tBu2PC2H4PtBu2)Ni(η2-C6F6) (5) for which the molecular structure is also reported.

The complexes (cod)MCl 2 (M ) Pd, Pt; cod ) cis,cis-1,5-cyclooctadiene) react with Li 2 (cot) (cot ) cyclooctatetraene) in a 1,6-diene/diethyl ether mixture (1,6-diene ) hepta-1,6-diene, diallyl ether, dvds (1,3-divinyl-1,1,3,3-tetramethyldisiloxane)) to afford the isolated homoleptic dinuclear Pd 0 and Pt 0 compounds Pd 2 (C 7 H 12 ) 3 (1), Pd 2 (C 6 H 10 O) 3 ‚C 6 H 10 O (2′; 2: Pd 2 (C 6 H 10 O) 3 ), Pd 2 (dvds) 3 (3), and Pt 2 (C 7 H 12 ) 3 (4). When 1-4 are treated with additional 1,6-diene the equally homoleptic but mononuclear derivatives of type M(1,6-diene) 2 (5-8) and with ethene the mixed alkene complexes (C 2 H 4 )M(1,6-diene) (9-12) are obtained in solution.Complexes 1-12 react with donor ligands such as phosphanes, phosphites, or t BuNC to give isolated complexes of types L-M(1,6-diene) (13-41), which have also been prepared by other routes. In all complexes the metal centers are TP-3 coordinated: complexes 1-4 contain chelating and bridging 1,6-diene ligands, whereas the other complexes contain a chelating 1,6-diene ligand and an η 2 -alkene (5-12) or η 1 -donor ligand (13-41). Of the studied 1,6-diene complexes the hepta-1,6-diene derivatives are most reactive, while the diallyl ether complexes are often more convenient to handle. The readily isolable dinuclear hepta-1,6-diene and diallyl ether complexes 1, 2′, and 4, and their mononuclear pure olefin derivatives are among the most reactive sources for naked Pd 0 and Pt 0 . The corresponding L-M(1,6-diene) complexes are equally reactive precursor compounds for the generation of [L-M 0 ] fragments in solution, which for M ) Pd are available otherwise only with difficulty. The results are significant for the operation of naked Pd 0 and L-Pd 0 catalysts in homogeneous catalysis.

Bispidine (3,7-diazabicyclo[3.3.1]nonane, C7H14N2) analogues of cisplatin, carboplatin, and oxaliplatin have been prepared. (C7H14N2)PtCl2·DMF (1b), obtained from (1,5-hexadiene)PtCl2 and bispidine in DMF, is dimeric in the solid state. Dissolving 1b in hot N-methylformamide allows crystallization of the solvent-free polymeric (C7H14N2)PtCl2 (1a). Recrystallization of 1a,b from hot water yields the trihydrate (C7H14N2)PtCl2·3H2O (1c). Reaction of 1 with Ag2(cbdca) (cbdca = 1,1-cyclobutanedicarboxylate) in water affords the pentahydrate (C7H14N2)Pt{C4H6(CO2)2}·5H2O (2b), which loses water in vacuo to give (C7H14N2)Pt{C4H6(CO2)2} (2a). Reaction of 1 with AgNO3 in water, followed by addition of Na2C2O4, affords the water-free polymeric (C7H14N2)Pt(C2O4) (3). All complexes have been structurally characterized, revealing various patterns of N-H···Cl and N-H···O hydrogen bonds. In the hydrates 1c and 2b the complexes are embedded in intricate three-dimensional water networks. Complexes 1a, 2a, and 3 have been tested for their cytotoxicity against human cancer cell lines K562 (chronic myeloid leukemia), A2780 (ovarian cancer), and its platinum-resistant subline A2780 CisR and are compared to their parent analogues. The new complexes show significant cytotoxic activity along with a low platinum resistance factor.

Attempts are described to synthesize ionic 14e [(π-allyl)Pd(NHC)]Y complexes (NHC ) C(N( t Bu)-CH) 2 , C(N(C 6 H 3 -2,6-i Pr 2 )CH) 2 ). Reaction of {(η 3 -2-RC 3 H 4 )Pd(µ-Cl)} 2 (R ) H, Me) with AgOTf yields polymeric, helical {(η 3 -C 3 H 5 )Pd(µ-OTf)} n (5a) and dimeric {(η 3 -2-MeC 3 H 4 )Pd(µ-OTf)} 2 (5b). Treatment of (η 3 -2-RC 3 H 4 )Pd(NHC)Cl (R ) H, Me) (6a-d) with LiMe or (tmeda)MgMe 2 affords the Pd-methyl complexes (η 3 -2-RC 3 H 4 )Pd(NHC)CH 3 (7a-d). Adduct formation of 5a,b with NHC, metathesis of 6a-d with AgOTf, and protolysis of 7c,d with HOTf yield the triflate complexes (η 3 -2-RC 3 H 4 )Pd(NHC)(OTf) (8a-d), whereas protolysis of 7a,b with acids (HOTf, HBF 4 ) results in complex degradation. From the reactions of 6a,c with AgBF 4 in THF, and AgPF 6 and AgAlR F 4 (R F ) OC(CF 3 ) 3 ) in THF and CH 2 Cl 2 , respectively, the ionic THF-solvates 9c(BF 4 ); PF 6 , 9c(PF 6 )) and the CH 2 Cl 2 -solvates [(η 3 -C 3 H 5 )Pd{C(N( t Bu)CH) 2 }(CH 2 Cl 2 )]AlR F 4 (11a(AlR F 4 )) and [(η 3 -C 3 H 5 )Pd{C(N(C 6 H 3 -2,6-i Pr 2 )CH) 2 }(CH 2 Cl 2 )]PF 6 ‚2CH 2 Cl 2 (11c(PF 6 )) have been isolated. In contrast, reaction of 6a,c with AgBF 4 in toluene or CH 2 Cl 2 yields the neutral solvent-free BF 4 adducts (η 3 -C 3 H 5 )Pd{C(N( t Bu)CH) 2 }(BF 4 ) (12a) and (η 3 -C 3 H 5 )Pd{C(N(C 6 H 3 -2,6-i Pr 2 )CH) 2 }(BF 4 ) (12c), consistent with the marked nucleophilicity of the BF 4 anion. Drying the CH 2 Cl 2 -solvates 11a,c(Y) (Y ) PF 6 , AlR F 4 ) at ambient temperature under vacuum affords the PF 6 and AlR F 4 adducts (η 3 -C 3 H 5 )Pd{C(N( t Bu)CH) 2 }-Reaction of 8-14 with water produces the (nonisolated) water adducts [(η 3 -C 3 H 5 )Pd(NHC)(H 2 O)]Y (10a-d(Y)). The molecular structures of 5a, 9a(BF 4 ), 11c(PF 6 ), and 12a have been determined. The various anions and solvate ligands are arranged in their order of donor strength/nucleophilicity toward the [(π-allyl)Pd(NHC)] + moiety.

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