Racemic carborane-based bisphosphanes were obtained by dismutation reactions between a carborane-based diphosphetane and diaryl dichalogenides. NMR spectroscopic and theoretical studies revealed a two-step mechanism explaining the high stereoselectivity of these reactions. The coordination chemistry of the multidentate P,N ligands 6c and 6d in copper(I) and silver(I) complexes was studied. While 6d acted exclusively as tetradentate ligand, 6c showed either tridentate or tetradentate coordination depending on the metal and the counterion.

A promising strategy for new electrically conductive coordination polymers is the combination of d 10 metal ions, which tolerate short metal•••metal distances, with dithiolene linkers, known for their "non-innocent" redox behavior. This study explores the coordination chemistry of 2,3-pyrazinedithiol (H 2 pdt) toward Cu + and Ag + ions, highlighting similarities and differences. The synthetic approach, starting with the fully protonated ligand, allowed the isolation of a homoleptic bis(dithiolene) complex with formal Cu I atoms, [Cu(H 2 pdt) 2 ]Cl (1). This complex was further transformed to a 1D coordination polymer with short metal•••metal distances, 1D [Cu(Hpdt)] (2 Cu ). The larger Ag + ion directly built up a very similar coordination polymer, 1D [Ag(Hpdt)] (2 Ag ), without any appearance of an intermediate metal complex. The coordination polymer 1D [Cu(H 2 pdt)I] (4), like complex 1, bears fully protonated H 2 pdt ligands in their dithione form. Upon heating, both compounds underwent auto-oxidation coupled with a dehydrogenation of the ligand to form the open-shell neutral copper(II) complex [Cu(Hpdt) 2 ] (3) and the coordination polymer 1D [Cu 2 I 2 (H 2 pdt)(Hpdt)] (5), respectively. For all presented compounds, crystal structures are discussed in-depth. Furthermore, properties of 1, 3, and those of the three 1D coordination polymers, 2 Ag , 2 Cu , and 4, were investigated by UV−vis−NIR spectroscopy, cyclic voltammetry, and variabletemperature magnetic susceptibility, and direct current (dc)-conductivity measurements. The experimental results are compared and discussed with the aid of DFT simulations.

The synthesis, structure, magnetic, and photophysical properties of two dinuclear, luminescent, mixedligand [Cr III 2 L(O 2 CR)] 3 + complexes (R = CH 3 (1), Ph (2)) of a 24membered binucleating hexa-aza-dithiophenolate macrocycle (L) 2À are presented. X-ray crystallographic analysis reveals an edge-sharing bioctahedral N 3 Cr(μ-SR) 2 (μ 1,3 -O 2 CR)CrN 3 core structure with μ 1,3 -bridging carboxylate groups. A ferromagnetic superexchange interaction between the electron spins of the Cr 3 + ions leads to a high-spin (S = 3) ground state. The coupling constants (J = + 24.2(1) cm À 1 (1), + 34.8(4) cm À 1 (2), H = À 2JS 1 S 2 ) are significantly larger than in related bis-μalkoxido-μ-carboxylato structures. DFT calculations performed on both complexes reproduce both the sign and strength of the exchange interactions found experimentally. Frozen methanol-dichloromethane 1 : 1 solutions of 1 and 2 luminesce at 750 nm when excited into the 4 LMCT state on the 4 A 2 ! 2 T 1 (ν 2 ) bands (λ exc = 405 nm). The absolute quantum yields (Φ L ) for 1 and 2 were found to be strongly temperature dependent. At 77 K in frozen MeOH/CH 2 Cl 2 glasses, Φ L = 0.44 � 0.02 (for 1), Φ L = 0.45 � 0.02 (for 2).

The synthesis of mixed-ligand complexes of the type [M2L(μ-L')]+, where L represents a 24-membered macrocyclic hexaaza-dithiophenolate ligand, L' is an azobenzene carboxylate co-ligand, and M = Cd(II), Ni(II) or Zn(II), is reported. A series of new complexes were synthesized, namely [M2L(μ-L')]+ (L' = azo-H, M = Cd (1), Ni (2); L' = azo-OH, M = Zn (3), Ni (4); L' = azo-NMe2, M = Zn (5), Cd (6), Ni (7); L' = azo-CO2Me, M = Cd (8), Ni (9)), and characterized by elemental analysis, electrospray ionization mass spectrometry (ESIMS), IR, UV–vis and NMR spectroscopy (for diamagnetic Zn and Cd complexes) and X-ray single crystal structure analysis. The crystal structures of 3' and 5–8 display an isostructural series of compounds with bridging azobenzene carboxylates in the trans form. The paramagnetic Ni complexes 2, 4 and 7 reveal a weak ferromagnetic exchange interaction with magnetic exchange coupling constant values between 21 and 23 cm−1 (H = −2JS1S2). Irradiation of 1 with λ = 365 nm reveals a photoisomerization of the co-ligand from the trans to the cis form.

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