Diborane(6) and Its Analogues Stabilized by Mono-, Bi-, and Trinuclear Group 7 Templates: Combined Experimental and Theoretical Studies

Abstract

Irradiation of [Re2(CO)10] in the presence of BH3·thf resulted in the formation of several rhenium diborane(6) species, for example, [{(OC)4Re}­{Re­(CO)3}2(μ3-η2:η2:η2-B2H6)­(μ-H)], 1; [{(OC)4Re}2{Re­(CO)3}­(μ3-η2:η2:η1-B2H6)­(μ-H)], 2; and [{(OC)4Re}2(μ-η2:η2-B2H6)], 3, comprising diverse coordination modes of the [B2H6]2– ligand. Compound 1 contains a tris­(bidentate) [B2H6]2– unit, whereas 2 consists of an unsymmetrically bound [μ3-η2:η2:η1-B2H6]2– ligand. In contrast, the irradiation of [Mn2(CO)10] with BH3·thf yielded only the Mn analogue of 1, [{(OC)4Mn}­{Mn­(CO)3}2(μ3-η2:η2:η2-B2H6)­(μ-H)], 1′. In an attempt to generate the bimetallic Mn-diborane(6), we have carried out the reaction of 1′ with PCy3 under photolytic conditions. The reaction led to the formation of two single base stabilized unsymmetrical diborane(5) species, [{Mn­(CO)3}­{Mn­(CO)2PCy3}­(μ-η2:η2-B2H5·PCy3)­(μ-H)], 4, and [{Mn­(CO)2PCy3}­(η3-B2H5·PCy3)], 5. As [B2H6]2– and [B2H5·PCy3]− are isoelectronic, the bondings in 4 and 5 are analogous to that of diborane(6) species 1–3. All the new species have been characterized spectroscopically, and their structures were further confirmed by single-crystal X-ray diffraction studies. DFT-type quantum chemical calculations were carried out that provided insight into the bonding interaction of [B2H6]2– and [B2H5·PCy3]− with the M­(CO) n fragments.

Monocyclopentadienyltitanium(III) Complexes with Hydridoborato Ligands

“…The remaining four hydrogens of each B 2 H 6 ligand are bridging the Ti(1) and Ti(1) i atoms, which exhibit classical four-legged piano stool geometries with four hydrides at the legs. While the coordination mode μ-κ 2 :κ 2 is well-documented for (B 2 H 6 ) 2– ligands, examples of structurally characterized μ 3 -κ 2 :κ 2 :κ 2 -B 2 H 6 groups are limited to a few trinuclear manganese or rhenium carbonyl complexes . The B–B bond length of 1.746(3) Å in 5 is slightly longer than those found in the mentioned group 7 complexes (1.681(6)–1.706(7) Å).…”

Metal‐Rich Metallaboranes: Synthesis, Structure, and Bonding of Heteronuclear Trimetallic Clusters containing (μ3‐BH) Ligand

“…The boron atoms are situated approximately 1.379 Å and 1.442 Å above the Ru1‐Mn1‐Ru2 plane of 2 and Ru1‐Re1‐Ru2 plane of 3 , respectively. The Mn1‐H2 (1.56(3) Å) bond length is shorter than the related manganese hydrido complexes [29] . Although the X‐ray analysis failed to locate the bridging Re−‐H−B hydrogen atom in 3 , 1 H NMR spectrum clearly validated its existence.…”

“…The Mn1-H2 (1.56(3) Å) bond length is shorter than the related manganese hydrido complexes. [29] Although the X-ray analysis failed to locate the bridging ReÀ -HÀ B hydrogen atom in 3, 1 H NMR spectrum clearly validated its existence. The RuÀ Ru bond distances of 2 (2.7892(4) Å) and 3 (2.7934(6) Å) are comparable with the RuÀ Ru bond in the triply bridging borylene species listed in Table 1.…”

Vertex-Fused Clusters Featuring a Flattened Butterfly

“…Polyhedral clusters that typically range from transition metals to boron hydrides have attracted great interest due to their structural appeal, unique bonding, and widespread applications. , Starting from the synthesis of small cage clusters to higher nuclearity clusters, polyhedral cluster chemistry has been developed in a pleasing fashion during the last few decades . In this regard, arachno -four-vertex clusters usually have butterfly cores that have been isolated in three different shapes: acutely bent, bent, and planar. − Out of these three shapes, the synthesis of molecules with planar butterfly cores has met with very little success (Chart ). ,, Although there are few examples of tetrametallic flattened or nearly flattened butterfly clusters, butterfly clusters having main-group and transition-metal vertices are very rare.…”