Carbonyl Diisocyanate CO(NCO)₂: Synthesis and Structures in Solid State and Gas Phase

Abstract

A modified synthesis for carbonyl diisocyanate, CO(NCO)2, starting from trichloroisocyanuric acid and diphosgene is described. In addition to the previously reported (13)C NMR resonances, the (15)N NMR shift is determined for the first time. The structure in the solid state was determined by X-ray diffraction (XRD) on in situ grown crystals, that in the gas phase was experimentally determined by electron diffraction (GED) and for single molecules theoretically by quantum-chemical calculations. The structures are compared and discussed with related systems. Quantum-chemical calculations as well as GED and XRD prove syn-syn to be the conformation of lowest energy. In quantum-chemical calculations and GED the presence of a syn-anti conformer was confirmed and the structure of this conformer was determined.

Photolysis of Carbonyl Diisocyanate: Generation of Isocyanatocarbonyl Nitrene and Diazomethanone

“…At room temperature, the composition of the two conformers in the gas phase was 62 % syn – syn and 38 % syn – anti , whilst the abundance of the less‐stable syn – anti conformer was significantly higher than that for OC(N 3 ) 2 (12 %) . The estimated abundance of the syn – syn conformer from the gas‐phase IR spectroscopic analysis was consistent with that derived from GED analysis (66(3) %) …”

Heterocumulene Sulfinyl Radical OCNSO

“…In syn OCNSO the structural parameters of the NCO moiety (Figure ) are similar to those in other NCO‐containing species like OC(NCO) 2 ( r (NC)=1.226(1) Å, r (CO)=1.150(1) Å), ∡(NCO)=172.5(1)°, X‐ray diffraction) . Whereas, the structure of the OSN moiety is quite different to those in the free NSO radical ( r (NS)=1.493 Å, r (SO)=1.449 Å), ∡(OSN)=125.2°, CcCR QFF) and HNSO⋅ B(C 6 F 5 ) 3 adduct ( r (NS)=1.530(2) Å, r (SO)=1.427(2) Å), ∡(OSN)=114.3(2)°, X‐ray diffraction) .…”

Photodecomposition of 1H‐Pyrrole Carbonyl Azides: Direct Observation of Singlet 1H‐Pyrrole Carbonyl Nitrenes and Triplet 1H‐3‐Pyrrylnitrene

“…Hence, no convincing evidence for the presence of a second conformer in matrix could be obtained. It should be noted that the preference syn configuration between C=O and N 3 has been frequently observed for other acyl azides and closely related isocyanates such as HC(O)N 3 , OC(N 3 ) 2 , and OC(NCO) 2 …”

“…It should be noted that the preference syn configuration between C=O and N 3 has been frequently observed for other acyl azides and closely related isocyanates such as HC(O)N 3 , [7] OC(N 3 ) 2 , [8] and OC(NCO) 2 . [25] X-ray Crystallography of 1 and 5 In line with the band shifts observed in the solid and N 2matrix IR spectra, the two molecules are linked to each other through two coplanar weak intermolecular hydrogen bonds (N4-H1•••O1=C1) with equal lengths of 2.184 Å, forming a tenmembered ring (Figure 3A). The length of the corresponding [26] In contrast, 1H-pyrrole-3-carbonyl azide (5) crystallizes in the monoclinic P2 1 /c space group with four molecules in the unit cell.…”