Carba-closo-dodecaboranylethynyl ligands facilitating luminescent reversed charge-transfer excited states in gold/silver complexes.

A set of mono- and dinuclear Au and Ag alkynyl complexes bearing the carba-closo-dodecaboranylethynyl ligand show intense room temperature phosphorescence. The {closo-1-CB} cage participates in an unprecedented way as an electron donating moiety, changing the direction of the charge-transfer excited state.

Synthesis of the fluorohydridoborate anions [BHF] and [1-HFB-9,12-X-closo-1,2-CBH] (X = H, I): deboronation of 1,2- and 1,7-dicarba-closo-dodecaboranes with anhydrous [MeN]F.

Deboronation of closo-1,7-CBH and 1-R-closo-1,2-CBH (R = Me, Ph) with anhydrous [MeN]F yields [MeN][BHF] that is the first structurally characterized anion of the series [BHF] (x = 1-3). Deboronation of 9,12-R-closo-1,7-CBH (R = H, I) gives a mixture of [MeN][BHF] and [MeN][1-HFB-9,12-R-closo-1,2-CBH].

Carba-closo-dodecaborate anions with two functional groups: [1-R-12-HC≡C-closo-1-CB₁₁H₁₀]⁻ (R = CN, NC, CO₂H, C(O)NH₂, NHC(O)H).

Disubstituted carba-closo-dodecaborate anions with one functional group bonded to the cluster carbon atom and one ethynyl group bonded to the antipodal boron atom were synthesized from easily accessible {closo-1-CB11} clusters. [Et4N][1-NC-12-HC≡C-closo-1-CB11H10] ([Et4N]4b) was prepared starting from Cs[12-Et3SiC≡C-closo-1-CB11H11] (Cs1c) via salts of the anions [1-HO(O)C-12-HC≡C-closo-1-CB11H10](-) (2b) and [1-H2N(O)C-12-HC≡C-closo-1-CB11H10](-) (3b). In a similar reaction sequence [Et4N][1-CN-12-HC≡C-closo-1-CB11H10] ([Et4N]7b) was obtained from Cs[1-H2N-12-HC≡C-closo-1-CB11H10] (Cs5b) by formamidation to yield [Et4N][1-H(O)CHN-12-HC≡C-closo-1-CB11H10] ([Et4N]6b) and successive dehydration.

Difunctionalized {closo-1-CB11 } clusters: 1- and 2-amino-12-ethynylcarba-closo-dodecaborates.

Carba-closo-dodecaborate anions with two functional groups have been synthesized via a simple two-step procedure starting from monoamino-functionalized {closo-1-CB11 } clusters. Iodination at the antipodal boron atom provided access to [1-H2 N-12-I-closo-1-CB11 H10 ](-) (1 a) and [2-H2 N-12-I-closo-1-CB11 H10 ](-) (2 a), which have been transformed into the anions [1-H2 N-12-RCC-closo-1-CB11 H10 ](-) (R=H (1 b), Ph (1 c), Et3 Si (1 d)) and [2-H2 N-12-RCC-closo-1-CB11 H10 ](-) (R=H (2 b), Ph (2 c), Et3 Si (2 d)) by microwave-assisted Kumada-type cross-coupling reactions. The syntheses of the inner salts 1-Me3 N-12-RCC-closo-1-CB11 H10 (R=H (1 e), Et3 Si (1 f)) and 2-Me3 N-12-RCC-closo-1-CB11 H10 (R=H (2 e), Et3 Si (2 f)) are the first examples for a further derivatization of the new anions.

Quantum-chemical and electrochemical investigation of the electrochemical windows of halogenated carborate anions.

The range of electrochemical stability of a series of weakly coordinating halogenated (Hal=F, Cl, Br, I) 1-carba-closo-dodecaborate anions, [1-R-CB(11)X(5)Y(6)](-) (R=H, Me; X=H, Hal, Me; Y=Hal), has been established by using quantum chemical calculations and electrochemical methods. The structures of the neutral and dianionic radicals, as well as the anions, have been optimized by using DFT calculations at the PBE0/def2-TZVPP level. The calculated structures are in good agreement with existing experimental data and with previous calculations.

Microwave-assisted Kumada-type cross-coupling reactions of iodinated carba-closo-dodecaborate anions.

The microwave-assisted Pd-catalyzed Kumada-type cross-coupling reaction of iodinated carba-closo-dodecaborate anions requires smaller amounts of Grignard reagent and catalyst and results in higher yields in much shorter reaction times in comparison to a reaction with conventional heat transfer. 12-Ph(3)P-closo-1-CB(11)H(11) was identified as the side product of the cross-coupling reactions that use [PdCl(2)(PPh(3))(2)]. The inner salt, which is the first example for a {closo-1-CB(11)} cluster with a B-P bond, was selectively synthesized via a related microwave-assisted cross-coupling protocol and characterized by NMR spectroscopy, elemental analysis, and single-crystal X-ray diffraction.

2-Aza-niumylcarba-closo-dodeca-borate ethanol monosolvate.

Two formula units of the title compound, 2-H(3)N-closo-1-CB(11)H(11)·CH(3)CH(2)OH or CH(14)B(11)N·C(2)H(5)OH, form a ring motif of R(4) (2)(8) type in the solid state that surrounds a crystallographic center of symmetry. The ring motif is a result of N-H⋯O hydrogen bonds. In contrast to many structures of {closo-1-CB(11)} clusters, the assignment of the position of the cluster C atom in the structure of the title compound is unambigious.

Salts of the Lewis-acidic dianion [Hg(closo-1-CB11F11)2]2-: coordination of acetonitrile and water.

The coordination of acetonitrile and water to the Hg atom in [Hg(closo-1-CB(11)F(11))(2)](2-) (1) reveals the Lewis acidity of the Hg(II) center, which is unprecedented, since 1 is a dianion. Both coordination compounds were characterized by single-crystal X-ray diffraction, vibrational spectroscopy, and differential scanning calorimetry (DSC). In contrast, the Hg atom in [PhHg(closo-1-CB(11)F(11))](-) (2) does not coordinate to CH(3)CN and H(2)O, although it has only a single negative charge.