Title:	Electronic structure of organometallic complexes having pi-bonds to phosphorus and arsenic
DNr:	NAISS 2025/22-996
Project Type:	NAISS Small Compute
Principal Investigator:	Anders Reinholdt <anders.reinholdt@chem.lu.se>
Affiliation:	Lunds universitet
Duration:	2025-07-31 – 2026-02-01
Classification:	10404
Keywords:

Abstract

The chemistry of organometallic complexes bearing multiple bonds to group 15 elements such as phosphorus (P) and arsenic (As) is a highly challenging synthetic area because the 3p and 4p orbitals of these atoms are spatially diffuse and intrinsically poor at forming stable pi-bonded linkages. My research group specializes in this area, and we recently published an Os=N=P system in Nature Communications (https://doi.org/10.1038/s41467-025-60669-6). A central component of this study was to describe the bonding in the system theoretically, using Density Functional Theory (DFT). We have now made three new families of organometallic complexes, which will also require a thorough theoretical electronic structure study. 1) We have made an Os=N=As system, which shows completely different spectroscopy and reactivity compared to our previously reported P system. Understanding the origin of these differences is central. 2) We have made a mixed-valent vanadium phosphide, V=P=V, with a total of three d-electrons. From preliminary magnetic studies, the complex seems to undergo a magnetic high-spin to low-spin transition around 110 K. Determining the nature of these spin-states is crucial. 3) We have made a Ir-P=CR2 system, which shows restricted R-to-R interconversion and hence P=C double bond character. We need electronic structure studies of the iridium complex (and several precursors). If the allocated computing time allows it, we will also calculate barriers for interconversion ; there are some cool mechanistic scenarios, including ones where the metal actively takes part in forming the transition state structure and ones where it does not. These are hard to tell apart in standard NMR studies, so computational insight could really help. Overall, we expect to study about 20 novel P/As-based multiply-bonded systems, and we request 20 x 1000 core-h/month to initiate the project (Starting ASAP).