Related Experiment Video

Updated: Jan 11, 2026

Author Spotlight: Experimental Approaches for the Synthesis of Low-Valent Metal-Organic Frameworks from Multitopic Phosphine Linkers

Author Spotlight: Experimental Approaches for the Synthesis of Low-Valent Metal-Organic Frameworks from Multitopic Phosphine Linkers

Published on: May 12, 2023

Structural insights into transition-metal-aminodiphosphine (PNP) complexes bearing [MCl_n(PNP)₂] (M = Co, Ru, Cr or

Sizwe J Zamisa¹, Adesola A Adeleke¹, Dunesha Naicker¹

¹School of Agriculture and Science, Discipline of Chemistry, University of KwaZulu-Natal, Private Bag X54001, Westville, Durban, 4000, South Africa.

Acta Crystallographica. Section C, Structural Chemistry

|November 10, 2025

Abstract:

The molecular structures of two novel cobalt aminodiphosphine (PNP) complexes (1 and 2) are reported, namely, bis[bis(diphenylphosphanyl)(pentyl)amine-κ²P,P']chloridocobalt(III) di-μ-chlorido-bis[dichloridocobalt(II)], [CoCl(C₂₉H₃₁NP₂)₂][Co₂Cl₆], and bis[bis(diphenylphosphanyl)(propan-2-yl)amine-κ²P,P']chloridocobalt(III) di-μ-chlorido-bis[dichloridocobalt(II)], [CoCl(C₂₇H₂₇NP₂)₂][Co₂Cl₆], featuring variation in the N-atom substituent, i.e. n-pentyl in complex 1 and isopropyl in complex 2. The asymmetric unit of complex 1 contains a five-coordinated cationic [CoCl{κ²-P,P-(N)-C₅H₁₁}₂]²⁺ species and a [Co₂(μ₂-Cl)₂Cl₄]^2- anion, while complex 2 includes a five-coordinated cation [CoCl{κ²-P,P-(N)-C₃H₇}₂], half a [Co₂(μ₂-Cl)₂Cl₄]^2- anion, and disordered diethyl ether and dichloromethane solvent molecules. The impact of ligand-induced strain, particularly due to the small bite angles of the PNP aminodiphosphine ligands, was examined in the context of geometric constraints and their influence on stability and reactivity. A Cambridge Structural Database (CSD) survey, along with a noncovalent interaction (NCI) analysis of the analogous [TMCl_n(PNP)₂] (where TM = transition metal and n = 1 or 2) core, revealed an inverse correlation between P-TM-P bite angles and N...TM contact distances. This correlation is attributed to the influence of the van der Waals radius of the metal: smaller metals allow wider bite angles and stronger N...TM contacts, whereas larger metals favour narrower bite angles and longer N...TM distances. NCI analysis indicated significant steric repulsion at the TM...N contacts, reflecting strain imposed by ligand geometry. A comparison of sign(λ₂)ρ eigenvalues suggests that Mo-P bonds exhibit weaker attractive interactions relative to Co-P and Ru-P bonds, with Cr-P bonds being the weakest. These findings provide pointers to structural and electronic factors governing coordination in PNP-ligated transition-metal complexes, offering rational design and catalytic and material applications.

Keywords:

CSD survey cobalt aminodiphosphine complexes crystal structure noncovalent interactions

More Related Videos

A Technical Guide for Performing Spectroscopic Measurements on Metal-Organic Frameworks

A Technical Guide for Performing Spectroscopic Measurements on Metal-Organic Frameworks

Published on: April 28, 2023

Structure and Coordination Determination of Peptide-metal Complexes Using 1D and 2D 1H NMR

Structure and Coordination Determination of Peptide-metal Complexes Using 1D and 2D 1H NMR

Published on: December 16, 2013

Related Concept Videos

Valence Bond Theory

Valence Bond Theory

Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...

Properties of Transition Metals

Properties of Transition Metals

Transition metals are defined as those elements that have partially filled d orbitals. As shown in Figure 1, the d-block elements in groups 3–12 are transition elements. The f-block elements, also called inner transition metals (the lanthanides and actinides), also meet this criterion because the d orbital is partially occupied before the f orbitals.

Metal-Ligand Bonds

Metal-Ligand Bonds

The hemoglobin in the blood, the chlorophyll in green plants, vitamin B-12, and the catalyst used in the manufacture of polyethylene all contain coordination compounds. Ions of the metals, especially the transition metals, are likely to form complexes.
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...

Coordination Number and Geometry

Coordination Number and Geometry

For transition metal complexes, the coordination number determines the geometry around the central metal ion. Table 1 compares coordination numbers to molecular geometry. The most common structures of the complexes in coordination compounds are octahedral, tetrahedral, and square planar.

Colors and Magnetism

Colors and Magnetism

Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...

Ladder Diagrams: Complexation Equilibria

Ladder Diagrams: Complexation Equilibria

Ladder diagrams are useful for evaluating equilibria involving metal-ligand complexes. The vertical scale of the ladder diagram represents the concentration of unreacted or free ligand, pL. The horizontal lines on the scale depict the log of stepwise formation constants for metal-ligand complexes and indicate the dominant species in all the regions.
The formation constant, K1, for the formation of Cd(NH3)2+ complex from cadmium and ammonia is 3.55 × 102. Log K1 (i.e. pNH3) is 2.55, and...

Articles linked to this work by shared authors, journal, and citation graph.

(E)-N-(4-Bromo-phen-yl)-1-(quinolin-2-yl)methanimine.

IUCrData·2026

1,3,5-Tri-aza-7-phosphaadamantan-1-ium nitrate.

IUCrData·2026

N,N'-Bis(2,6-diiso-propyl-phen-yl)-N-hy-droxy-formamidine-N,N'-bis-(2,6-diiso-propyl-phen-yl)-N-oxidoformamidinium (1/1).

IUCrData·2026

Tris(3,5-di-aza-1-azonia-7-phosphaadamant-7-yl)(1,3,5-tri-aza-7-phospha-adamantane)silver(I) dicarbonate.

IUCrData·2026

Review of Glycerol Conversion to Glycerol Carbonate via Alkyl Carbonates: Reflections, Future Perspective and Catalytic Roles of Mixed/Promoted Metal Oxides and Mechanistic Insights from DFT.

Molecules (Basel, Switzerland)·2026

(2-Amino-cyclo-hexanol-κ2 N,O)chlorido(η6-p-cy-mene)ru-thenium(II) tetra-fluoro-borate (2-amino-cyclo-hexanolato-κ2 N,O)chlorido(η6-p-cymene)ru-thenium(II).

IUCrData·2026

See all related articles