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Isolation of planar [B6H6] is a long‐awaited goal in boron chemistry. Several attempts in the past to stabilize [B6H6] were unsuccessful due to the domination of polyhedral geometries. Herein, we report the synthesis of a triple‐decker sandwich complex of titanium [(Cp*Ti)2(μ‐η6 : η6‐B6H6)(μ‐H)6] (1), which features the first‐ever experimentally achieved nearly planar six‐membered [B6H6] ring, albeit within a [B6H12] borate. The small deviation from planarity is a direct consequence of the predicted structural pattern of the middle ring in 24 Valence Electron Count (VEC) triple‐decker complexes. The large ring size of [B6H6] in 1 brings the metal–metal distance into the bonding range. However, significant electron delocalization from the M−M bonding orbital to the bridging hydrogen and B−B skeleton in the middle decreases its bond strength. [ABSTRACT FROM AUTHOR]

Isolation of planar [B6H6] is a long‐awaited goal in boron chemistry. Several attempts in the past to stabilize [B6H6] were unsuccessful due to the domination of polyhedral geometries. Herein, we report the synthesis of a triple‐decker sandwich complex of titanium [(Cp*Ti)2(μ‐η6 : η6‐B6H6)(μ‐H)6] (1), which features the first‐ever experimentally achieved nearly planar six‐membered [B6H6] ring, albeit within a [B6H12] borate. The small deviation from planarity is a direct consequence of the predicted structural pattern of the middle ring in 24 Valence Electron Count (VEC) triple‐decker complexes. The large ring size of [B6H6] in 1 brings the metal–metal distance into the bonding range. However, significant electron delocalization from the M−M bonding orbital to the bridging hydrogen and B−B skeleton in the middle decreases its bond strength. [ABSTRACT FROM AUTHOR]

Isolation of planar [B6H6] is a long‐awaited goal in boron chemistry. Several attempts in the past to stabilize [B6H6] were unsuccessful due to the domination of polyhedral geometries. Herein, we report the synthesis of a triple‐decker sandwich complex of titanium [(Cp*Ti)2(μ‐η6 : η6‐B6H6)(μ‐H)6] (1), which features the first‐ever experimentally achieved nearly planar six‐membered [B6H6] ring, albeit within a [B6H12] borate. The small deviation from planarity is a direct consequence of the predicted structural pattern of the middle ring in 24 Valence Electron Count (VEC) triple‐decker complexes. The large ring size of [B6H6] in 1 brings the metal–metal distance into the bonding range. However, significant electron delocalization from the M−M bonding orbital to the bridging hydrogen and B−B skeleton in the middle decreases its bond strength. [ABSTRACT FROM AUTHOR]

Isolation of planar [B6H6] is a long‐awaited goal in boron chemistry. Several attempts in the past to stabilize [B6H6] were unsuccessful due to the domination of polyhedral geometries. Herein, we report the synthesis of a triple‐decker sandwich complex of titanium [(Cp*Ti)2(μ‐η6 : η6‐B6H6)(μ‐H)6] (1), which features the first‐ever experimentally achieved nearly planar six‐membered [B6H6] ring, albeit within a [B6H12] borate. The small deviation from planarity is a direct consequence of the predicted structural pattern of the middle ring in 24 Valence Electron Count (VEC) triple‐decker complexes. The large ring size of [B6H6] in 1 brings the metal–metal distance into the bonding range. However, significant electron delocalization from the M−M bonding orbital to the bridging hydrogen and B−B skeleton in the middle decreases its bond strength. [ABSTRACT FROM AUTHOR]

We have synthesized and structurally characterized two new borate complexes of early transition metals utilizing chalcogen based borate ligand Li[BH 3 (SPh)]. [Display omitted] • Two unique chalcogen stabilized borate complexes of Ta were isolated. • Complex 1 has two unique borate ligands, i.e., {BH 3 (SPh)} and {BH 3 (S)}. • Compound 2 has another unique borate ligand {BH 3 (C 6 H 4)S} and triborane analog. • The DFT calculations revealed the σ-donation of B-H bonds of borates to Ta atoms. In an attempt to isolate some electron precise early transition metal borate complexes, we have explored the reactions of [Cp*TaCl 4 ] (Cp* = η 5-C 5 Me 5) with chalcogen-based borate ligand Li[BH 3 (SPh)]. The room-temperature reaction yielded bimetallic borate complex [(Cp*Ta) 2 (μ -SPh){S(BH 3)}{SPh(BH 3)}] (1) that present two types of borate ligands, i.e., {BH 3 (SPh)} and {BH 3 (S)} ligands having unique coordination with the tantalum atoms. Interestingly, the {BH 3 (S)} ligand is coordinated to both the Ta centers in µ-η1:η2 fashion. On the other hand, thermolysis of [Cp*TaCl 4 ] in the presence of Li[BH 3 (SPh)] yielded a bimetallic borate species [(Cp*Ta) 2 (µ - η 3: η 3-B 2 H 4 S){ µ - η 2: η 2-S(C 6 H 4)BH 3 }] (2). Compound 2 contains a triborane analog and a borate ligand, which are coordinated to two Ta atoms. This can also be considered as a notable example of C H activated molecule, in which a B-C bond formation took place. Both the borate species have been characterized by mass spectrometry, IR spectroscopy, NMR spectroscopy, and single-crystal X-ray diffraction studies. The density functional theory (DFT) calculations further provided insights into the bonding and electronic structures of these bimetallic borate species. [ABSTRACT FROM AUTHOR]