Bis(Dicarbollide) Complexes of Transition Metals: How Substituents in Dicarbollide Ligands Affect the Geometry and Properties of the Complexes.

The interaction between different types of substituents in dicarbollide ligands and their influence on the stabilization of various rotational conformers (rotamers) of transition metal bis(dicarbollide) complexes [3,3'-M(1,2-CBH)] are considered. It has been shown that the formation of intramolecular CH···X hydrogen bonds between dicarbollide ligands is determined by the size of the proton acceptor atom X rather than its electronegativity. Due to the stabilization of rotamers with different dipole moments, intramolecular hydrogen bonds between ligands in transition metal bis(dicarbollide) complexes can have a significant impact on the biological properties of their derivatives.

Charge-compensated -carborane derivatives in the synthesis of iron(II) bis(dicarbollide) complexes.

A series of stable iron(II) bis(dicarbollide) derivatives [8,8'-(RNHC(Et)HN)-3,3'-Fe(1,2-CBH)] (R = Pr, R = Ph, (CH)OH, (CH)OH, (CH)NMe) was prepared starting from FeCl or [FeCl(dppe)] and the corresponding -carboranyl amidines [10-RNHC(Et)HN-7,8-CBH]. In a similar way, the reactions of the oxonium derivatives of -carborane with FeCl in tetrahydrofuran in the presence of -BuOK lead to the corresponding stable oxonium derivatives iron(II) bis(dicarbollide) [8,8'-(RR'O)-3,3'-Fe(1,2-CBH)] (RR' = (CH), (CH)O(CH), (CH); R = R' = Et), which can be alternatively prepared by the reaction of the parent iron(II) bis(dicarbollide) with tetrahydrofuran or 1,4-dioxane in the presence of MeSO. The cyclic voltammetry studies of the synthesized iron(II) bis(dicarbollide) derivatives revealed that the introduction of amidinium and oxonium substituents leads to a significant increase in the Fe/Fe redox potential relative to the parent iron(II) bis(dicarbollide).

Development of a Gadolinium-Boron-Conjugated Albumin for MRI-Guided Neutron Capture Therapy.

Noninvasive monitoring of boron agent biodistribution is required in advance of neutron capture therapy. In this study, we developed a gadolinium-boron-conjugated albumin (Gd-MID-BSA) for MRI-guided neutron capture therapy. Gd-MID-BSA was prepared by labeling bovine serum albumin with a maleimide-functionalized gadolinium complex and a maleimide-functionalized -dodecaborate orthogonally.

Nickel(II) and Palladium(II) Complexes with η:κ()-Coordinated Dicarbollide Ligands Containing Pendant Pyridine Group.

A series of - and -substituted -carborane derivatives with a pendant pyridyl group was prepared. The synthesized compounds were used as ligands in the complexation reactions with bis(triphenylphosphine)nickel(II) and palladium(II) chlorides to give six new metallacomplexes with unusual η:κ()-coordination of the metal center. The single crystal structures of 1-(NCH-2'-S)-1,2-CBH, 1-(NCH-2'-CHS)-1,2-CBH, Cs [7-(NCH-2'-CHS)-7,8-CBH] - and -carboranes and 3-PhP-3-(4(7)-NCH-2'-S)--3,1,2-NiCBH and 3-PhP-3-(4(7)-NCH-2'-CHS)--3,1,2-NiCBH metallacarboranes were determined using single crystal X-ray diffraction.

New Boron Containing Acridines: Synthesis and Preliminary Biological Study.

The synthesis of the first conjugates of acridine with cobalt bis(dicarbollide) are reported. A novel 9-azido derivative of acridine was prepared through the reaction of 9-methoxyacridine with NCHCHNH, and its solid-state molecular structure was determined via single-crystal X-ray diffraction. The azidoacridine was used in a copper (I)-catalyzed azide-alkyne cycloaddition reaction with cobalt bis(dicarbollide)-based terminal alkynes to give the target 1,2,3-triazoles.