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First Bis(σ)‐borane Complexes of Group 6 Transition Metals: Experimental and Theoretical Studies
Author(s) -
Lenczyk Carsten,
Roy Dipak Kumar,
Ghosh Bijoy,
Schwarzmann Johannes,
Phukan Ashwini K.,
Braunschweig Holger
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201901075
Subject(s) - borane , chemistry , crystallography , transition metal , molybdenum , ligand (biochemistry) , molecule , ring (chemistry) , metal , center (category theory) , stereochemistry , inorganic chemistry , organic chemistry , catalysis , biochemistry , receptor
A series of bis(σ)‐borane complexes of Group 6 transition metals were prepared by direct dihydroborane coordination to the metal center. Reaction of [M(CO) 3 (PCy 3 ) 2 ] and two dihydroboranes [DurBH 2 ] and [(Me 3 Si) 2 NBH 2 ] (Dur=2,3,5,6‐Me 4 C 6 H) yielded bis(σ)‐borane complexes fac ‐[M(CO) 3 (PCy 3 ){η 2 ‐(H 2 BR)}] (R=Dur; 1 : M=Cr, 2 : M=W; R=N(SiMe 3 ) 2 ; 3 : M=Cr, 4 : M=W). In the case of molybdenum, we have isolated an arene complex ( 5 ) with [DurBH 2 ] in which the Dur group acts as a η 6 ‐bound ligand, and with [(Me 3 Si) 2 NBH 2 ] a similar bis(σ)‐borane complex was isolated, cis , trans ‐[Mo(CO) 2 (PCy 3 ) 2 {η 2 ‐(H 2 BN(SiMe 3 ) 2 }] ( 6 ), with a different pattern of auxiliary ligands. The complexes were investigated by multinuclear NMR spectroscopy, mass spectrometry, X‐ray diffraction analysis, and computational methods. Quantum theory of atoms in molecules (QTAIM) calculations demonstrated that the borane complexes may be described as pure bis(σ)‐borane complexes rather than elongated or stretched examples given that the calculations do not show the presence of a ring‐critical point (RCP) at the ring formed by the interactions of the B−H with metal center.