Triply Bonded Nb₂⁴⁺Tetragonal Lantern Compounds:  Some Accompanied by Novel B−H···Na⁺Interactions

Abstract

The diniobium tetragonal lantern compound Nb2(hpp)4, 1, has been prepared in high yields by the reaction of NbCl3(DME), DME = dimethoxyethane, with a mixture of lithium naphthalenide and Li(hpp), hpp = the anion of 1,3,4,6,7,8-hexahydropyrimido[1,2-a]pyrimidine. Compound 1 interacts with two equivalents of NaEt3BH to give the bis-adduct, 1·2NaEt3BH. In a refluxing mixture of THF/toluene, 1·2NaEt3BH loses one NaEt3BH molecule to give 1·NaEt3BH. Both adducts contain short Na to N−C−N “pseudo-allylic” interactions to the coordinated hpp ligand. Very little variation can be seen in the Nb−Nb bond distances, which are 2.2035(9), 2.2064(3), and 2.2187(7) Å for 1, 1·2NaEt3BH and 1·NaEt3BH, respectively. By a synthetic route similar to that used to make 1, Nb2(azin)4·2LiCl·4THF, 2, was prepared using the anion of 7-azaindole; the Cl- ions are loosely coordinated to the Nb atoms. This ligand tends to give long metal−metal distances, and the Nb−Nb distance of 2.278(2) Å is 0.07 Å longer than that in 1.

Metal‐Hydride Bonding in Higher Alkali Metal Boron Monohydrides

“…[23] Meanwhile, we are aware of only a single report of a four-membered Na 2 H 2 array; the mesitylene adduct {(η 6 -Me 3 C 6 H 3 )Na(µ-Et 3 BH)Na(µ-Et 3 BH)} 2 revealing a similar central metallocycle [H-Na 2.30(7) Å, 2.23(4) Å] based on pyramidalized hydride centers. [24] Scheme 4.…”

Clusters of Ammonium Cation—Hydrogen Bond versus σ‐Hole Bond

“…[1][2][3][4] The hydrogen bond is analyzed most often due to its importance in numerous chemical, physical, and biochemical processes. [2,4,6] One can mention such interactions as the hydride bond, for which the negatively charged H atom acts as the Lewis base center, and it is situated between two electropositive centers, [7][8][9][10] and the beryllium bond [11] or the dihydrogen bond, which is the contact between negatively and positively charged H atoms. [2,4,6] One can mention such interactions as the hydride bond, for which the negatively charged H atom acts as the Lewis base center, and it is situated between two electropositive centers, [7][8][9][10] and the beryllium bond [11] or the dihydrogen bond, which is the contact between negatively and positively charged H atoms.…”

“…[5] However, it was also pointed out that other noncovalent interactions play an important role in various reactions and processes. [2,4,6] One can mention such interactions as the hydride bond, for which the negatively charged H atom acts as the Lewis base center, and it is situated between two electropositive centers, [7][8][9][10] and the beryllium bond [11] or the dihydrogen bond, which is the contact between negatively and positively charged H atoms. [12] The latter interaction may be classified as a hydrogen bond from one side and also as a hydride bond from the other side.…”

Relationships between QTAIM and the Decomposition of the Interaction Energy – Comparison of Different Kinds of Hydrogen Bond

“…It has also been suggested this interaction is called the ''hydride bond'' [59], because the term ''inverse'' is usually reserved for so-called blue-shift hydrogen bonds [60]. This type of interaction (BaHÁÁÁNa þ ) has been observed in an experimental crystal structure [61]. The hydride bonding in the BeH 2 ÁÁÁLi þ , BeH 2 ÁÁÁNa þ , and BeH 2 ÁÁÁMg 2þ linear complexes, and the variation-perturbation partitioning of interaction energy, have recently been investigated by use of the QTAIM [59].…”