A new member of the Nbn(?3-X)n?2(?-X)nLn+6 (n > 2) cluster family: Nb4Cl10(PEt3)4(H2NPh)2. Synthesis, structure, and relationship to other members

Cyclopentadienyl-Silyl-Amido versus Imido Niobium Complexes. The Role of Additional Amine Functionalities: A Combined Experimental and Theoretical Study

“…In contrast, though the Nb-N(1) bond distance (1.996(2) Å) is similar to that found in 3a and comparable to those Nb-N bonds with an appreciable multiple bond character (1.935-2.102 Å), 43 the Nb-N(2) distance of 2.515(3) Å is notably longer than in 3a and is one of the longest reported (Nb-N bond range 1.93-2.51 Å), [44][45][46][47] such elongation also contributes to minimizing the strain in the metallacycle. The angles around N(2) are close to the ideal values expected for tetrahedral geometry and are consistent with sp 3 hybridization.…”

Synthesis, Characterization, and Reactivity of Niobium and Tantalum Complexes Bearing Metal−Nitrogen Bonds. X-ray Molecular Structure of [Nb(C5H4SiMe3){NH(CH2)2-η-NH2}Cl3] and the Novel Tetranuclear Niobium Oxo Derivative [{Nb(C5H4SiMe3)Cl(μ2-O)}4(Cl)2(μ3-O)]

“…The short Nb−N(1) bond distance (1.992(4) Å) is in the reported range for Nb−N bonds with an appreciable multiple-bond character (1.935−2.102 Å), and the planar environment of the N(1) atom, with the sum of the angles around it close to 360° and hence sp 2 -hybridized, suggests a perceptible N(pπ)−Nb(dπ) interaction. The coordination of the pendant NH 2 group is clearly shown with a Nb−N(4) distance of 2.255(5) Å, within the single-bond range (2.20−2.40 Å). − …”

Preparation and Characterization of a Tetranuclear and Mixed-Valence Nb(II)/Nb(III) Diamagnetic Nb4Cl12Li2(THF)8 Cluster

“…A few tetrametallic niobium clusters have been described in the literature of the higher oxidation states, and less than a handful of thiolates, alkoxides, and carboxylates have been reported. The present mixed-valence compound is formally composed of two trivalent and two divalent niobium atoms and has in a phosphine derivative reported a few years ago, (Me 3 P) 6 Nb 4 Cl 10 , one of the very few related precedents . Unfortunately, the magnetic properties were not reported for this particular complex and thus the presence of five Nb−Nb single bonds argued on the exclusive basis of the intermetallic distances remains putative.…”