V. V. Drozdova

Anionic silver(I) complexes with closo-dodecaborate anion

Silver(I) complex formation with closo-dodecaborate anion was studied systematically in various media: water, acetonitrile, and acetonitrile/trifluoroacetic acid (TFA). A possibility of formation of complexes Cat[AgB12H12] and [Ag2B12H12] was demonstrated. Synthesis parameters (reaction medium, reagent ratio, and cation size in precursor dodecaborate) were shown to affect the type of the resulting complex and the coordination sphere around the central atom.

Anionic Complexes of Cu(I) with the Closo-Decaborate Anion

General procedures for synthesis of anionic Cu(I) complexes with the closo-decaborate anion were worked out; they make it possible to prepare coordination compounds with a wide set of organic cations. The interaction of onium closo-decaborates with [Cu2B10H10] in acetonitrile acidified with anhydrous trifluoroacetic acid was found to be the most effective synthetic method that secures high yield and quality of the obtained products. The structure of (C2H5)3NH[CuB10H10] was determined by X-ray diffraction analysis.

Copper(I) coordination compounds with closo-dodecaborate anion

Copper(I) complexes with a closo-dodecaborate anion were synthesized: Cat[CuB12H12], where Cat = Cs+, Ph4P+, Ph4As+, or RxNH4−x+ (R = Me, Et, Pr, or Bu; x = 3 or 4). The complexes were synthesized from the copper(II)-closo-dodecaborate-sulfur dioxide (sodium sulfite) system. The structure of [Cu2(NCCH3)4B12H12] was determined using X-ray crystallography.

Crystal structure of (μ5-decahydro-closo-decaborato) (μ2-O-dimethylformamide)disilver(I) [Ag2(B10H10)(DMF)]

The compound [Ag2(B10H10)(DMF)] is synthesized, and its crystal structure is studied (R = 0.0699 for 2836 observed reflections). The coordination number of each of the four independent Ag atoms is 4 + 2. The nearest environment of the Ag(1) and Ag(4) atoms consists of two O atoms of the DMF molecules and two BH groups, and that of the Ag(2) and Ag(3) atoms consists of four BH groups. All the Ag atoms additionally form weak bonds with two BH groups. The Ag-O and Ag-B bonds lie in the ranges 2.319–2.465(9) and 2.46–2.70(1) Å, respectively, and the Ag⋯B distances are 2.89–3.25(1) Å. Due to the binding of each polyhedral anion to five Ag atoms, layers are formed. Bridging DMF molecules link layers into the three-dimensional framework.

The isomorphous substitution of 2H+ for the Cu2+ cation in the complex of bis(aminoguanidine)copper(II): Crystal structures of (Cu0.61H0.78Agu2)B12H12 and (HAgu)2B12H12

An X-ray diffraction study of the (Cu0.61H0.78Agu2)B12H12 (I) mixed crystal and one of its components (HAgu)2B12H12 (II) is performed at 160 K (R = 0.0312 and 0.0345, respectively). Crystals I and II are isostructural. In I, two H+ ions partially substitute the Cu2+ cation, resulting in a combination of [CuAgu2]2+ and (HAgu2)2+ cations in the structure. The cations and polyhedral B12H122− anions have centrosymmetric structures. A square planar environment for the Cu atom is formed by four N atoms of two Agu molecules, which close five-membered chelate cycles [Cu-N, 1.9702(13) and 2.0261(10) Å]. The distant apical vertices are occupied by H atoms of the B12H122− anions [Cu…H, 2.805(14) Å]. In the dimeric (HAgu2)2+ cations, the proton that substitutes for the Cu2+ cation forms a three-center N(1)-H…N(4),N(4)′ hydrogen bond which consists of intramolecular and an intermolecular components. In crystal II, the N(1)…N(4) and N(1)…N(4)′ distances [2.685(1) and 3.111(1) Å] are longer than in I [2.610(2) and 3.027(2) Å]. In I, the Cu…H interactions connect [CuAgu2]2+ cations and B12H122− anions into chains. In the cells that contain the (HAgu2)2+ dimeric cation, the chains are retained due to the secondary N-H…(B-H) interactions. Numerous weak secondary interactions between the cations and anions form three-dimensional frameworks in structures I and II.

Synthesis and structure of the polymeric complex [Ag2(Ph3P)2B10H10] n

A method for the synthesis of the silver(I) complex with the closo-decaborate anion and triphenylphosphine [Ag2(Ph3P)2B10H10]n was developed and the structure of this complex was studied. The polymeric chain of the complex is formed with participation of Ag(I) atoms, which coordinate the B10H102− anions through the apical (B(1)–B(2), B(9)–B(10)) and equatorial (B(3)–B(6), B(5)–B(8)) edges, the metalligand bonding occurring through three-center two-electron bonds (MHB). The P atoms of two triphenylphosphine molecules are also incorporated in the inner coordination sphere of the metal: the CN of the silver atom is 4 + 1.

Interaction of closo-decaborate anion B10H102− with iminium salts

The interaction of closo-decaborate anions with iminium salts, either formed in situ or introduced into the reaction as individual compounds, has been studied. The reaction leads to products with an exopolyhedral boron-nitrogen bond. The formation of compounds with exopolyhedral boron-chlorine and boron-carbon bonds is also possible. The crystal structures of [NMe2(CH2Cl)]2B10H8 and 3-CH3-2,8-[NMe2(CH2Cl)]2-7-ClB10H6 have been studied.

Reaction of the closo-decaborate anion B10H 10 2− with dichloroethane in the presence of hydrogen halides

The reactions of the closo-decaborate anion with hydrogen halides and dichloroethane have been studied. Irrespective of the hydrogen halide used (HCl, HBr, HI), chlorination to give mono-, di-, and trihalosubstituted products is the major process. The product ratio depends on the hydrogen halide used and on the synthesis temperature and time. The products have been identified by 11B NMR, IR, and ESI mass spectra. The structure of (Ph3(NaphCH2)P)2B10H8Cl2 has been studied by X-ray diffraction. The geometry distortion of the closo-decaborate core found in the chlorinated derivatives is retained on further chemical transformations of the compound.

Reaction of closo-dodecaborate anion B12H122− with iminium salts

The reaction of the closo-dodecaborate anion with iminium salts was studied. The iminium salts were either formed in situ or introduced into the reaction in an individual state. Mono-and disubstituted products with an exopolyhedral boron-nitrogen bond were found to form. The structures of compounds 1,7-[NMe2(CH2Cl)]2B12H10 and 1,7-[MeNPh(CH2Cl)]2B12H10 were determined using X-ray crystallography.

Isomerism of metal complexes with the boron cluster anions B10H102− and B12H122−

A new type of inner-sphere isomerism in coordination chemistry observed in metal complexes with boron cluster anions BnHn2− (n = 10, 12) is discussed. Specific structure of the closo-borohydride anions gives rise to edge and facial isomers, among which mirror isomers have been found. Examples of edge and facial isomers of metal complexes with the B10H102− and B12H122−, anions obtained experimentally and studied by X-ray diffraction are considered. Analysis of their structure revealed a new type of isomerism, which was called “positional.”