Reactions of the homoleptic acetonitrile complexes of palladium and platinum with diethylamine

Synthesis of Boronated Amidines by Addition of Amines to Nitrilium Derivative of Cobalt Bis(Dicarbollide)

A series of novel cobalt bis(dicarbollide) based amidines were synthesized by the nucleophilic addition of primary and secondary amines to highly activated B-N+≡C-R triple bond of the propionitrilium derivative [8-EtC≡N-3,3'-Co(1,2-C2B9H10)(1',2'-C2B9H11)]. The reactions with primary amines result in the formation of mixtures of E and Z isomers of amidines, whereas the reactions with secondary amines lead selectively to the E-isomers. The crystal molecular structures of E-[8-EtC(NMe2)=HN-3,3'-Co(1,2-C2B9H10)(1',2'-C2B9H11)], E-[8-EtC(NEt2)=HN-3,3'-Co(1,2- C2B9H10)(1',2'-C2B9H11)] and E-[8-EtC(NC5H10)=HN-3,3'-Co(1,2-C2B9H10)(1',2'-C2B9H11)] were determined by single crystal X-ray diffraction.

Cationic tri(ferrocenecarbonitrile)silver(I)

The synthesis of the tri-coordinated ferrocenecarbonitrile silver(I) complex [Ag(N≡CFc)3]OTf (3) is reported. Its electrochemical behavior shows that the three ferrocenyl units are oxidized in a very close potential range. In addition, the molecular structure of 3 in the solid state is discussed, showing that silver(I) is exclusively coordinated by three ferrocenecarbonitrile molecules.

Critical Role of Anions in Platinum(II) Precursors upon the Structural Motifs of Six-Membered Cycloplatinated N,N',N″-Triarylguanidines

The reactions of cis-[Pt(OAc)₂(DMSO)₂] with 2 equiv of sym N,N',N″-triarylguanidines, [ArN=C(NHAr)₂], in toluene under reflux condition for 8 h afforded six-membered cycloplatinated guanidines, [Pt{κ²(C,N)}(OAc){κ¹ N(ArN=C(NHAr)₂)}] [sym = symmetrical; Ar = 2-MeC₆H₄ (1) and 2,4-Me₂C₆H₃ (2)], in 82 and 84% yields, respectively. The salt metathesis reaction of 1 with 1 equiv of AgTFA in CH₂Cl₂ at room temperature (RT) afforded [Pt{κ²(C,N)}(TFA){κ¹ N(ArN=C(NHAr)₂)}] (3) in 94% yield. The reaction of cis-[Pt(TFA)₂(DMSO)₂] with 1 equiv of [ArN=C(NHAr)₂] in toluene under reflux condition for 8 h afforded six-membered cycloplatinated guanidines, [Pt{κ²(C,N)}(TFA)(DMSO)] [Ar = 2-MeC₆H₄ (4), 4-MeC₆H₄ (5), 2,4-Me₂C₆H₃ (6), and 2-(MeO)C₆H₄ (7)], in ≥73% yields. The reaction of trans-[PtCl₂(PhCN)₂] with 2 equiv of [ArN=C(NHAr)₂] in toluene under reflux condition for 48 h afforded trans-[PtCl₂{ArN=C(NHAr)₂}₂] [Ar = 2-MeC₆H₄ (8) and 2,4-Me₂C₆H₃ (9)] in 90 and 45% yields, respectively. Complexes 8 and 9 were separately refluxed in MeOH for 8 h to afford six-membered cycloplatinated guanidines, [Pt{κ²(C,N)}(μ-Cl)]₂ (10 and 11), in 93 and 96% yields, respectively, with concomitant formation of the respective guanidinium salts, [(ArNH)₃C]Cl, as the byproduct. Platinacycle 10 was treated with 2 equiv of AgTFA in CH₂Cl₂ at RT to afford six-membered cycloplatinated guanidine, [Pt{κ²(C,N)}(μ-TFA)]₂ (12), in 94% yield. The new compounds were characterized by analytical techniques and multinuclear NMR (¹H, ¹³C, and ¹⁹⁵Pt) spectroscopy, and further, molecular structures of 10 compounds were determined by single-crystal X-ray diffraction. The structural motif in 1·1/2CH₂Cl₂ and 3 is novel in that it contains a planar six-membered [Pt{κ²(C,N)}] unit and a nonplanar eight-membered [Pt{κ²(N,O)}] ring, wherein OAc and the guanidine ligands are linked through a N-H···O hydrogen bond. The six-membered cycloplatinated structural motifs present in 10/11·C₇H₈ and 12·CH₂Cl₂ are also unprecedented in the literature. The number and nature of solution species of new complexes were unambiguously investigated by detailed NMR studies. The critical role of anions in Pt(II) precursors upon the course of cycloplatination and thus the motifs in the products were addressed. Plausible mechanisms of cycloplatination reactions are discussed.

1,2-Dicyanoferrocene: synthesis and characterization

A convenient synthesis of 1,2-dicyanoferrocene (3) was developed by using 2,4-dinitrofluorobenzene as a dehydrating agent for the treatment of 1,2-ferrocenedicarbaldehyde dioxime (2) to give 3 in yields exceeding 80%. Compounds 2 and 3 have been characterized by IR and NMR (1H, 13C{1H}) spectroscopy and by electrochemistry (cyclic voltammetry and square-wave voltammetry). Furthermore, the molecular structures of 2 and 3 in the solid state have been determined by single-crystal X-ray crystallographic studies.

Chemistry and biological activity of platinum amidine complexes

Platinum amidine complexes represent a new class of potential antitumor drugs that contain the imino moiety HN=C(sp(2)) bonded to the platinum center. They can be related to the iminoether derivatives, which were recently shown to be the first Pt(II) compounds with a trans configuration endowed with anticancer activity. The chemical and biological properties of platinum amidine complexes, and more generally of platinum imino derivatives, can be rationally modified through suitable synthetic procedures with the aim of improving their cytotoxicity and antitumor activity. The addition of protic nucleophiles to nitriles coordinated to platinum in various oxidation states can offer a wide variety of complexes with chemical, structural, and physical properties specifically tuned for a more efficacious biological response.