Laser-ablated U atoms react with (CN)₂ in excess argon and neon during codeposition at 4 K to form UNC, U(NC)₂, and U(NC)₄ as the major uranium-bearing products, which are identified from their matrix infrared spectra using cyanogen substituted with ¹³C and ¹⁵N and from quantum chemical calculations. The ^12/13CN and C^14/15N isotopic frequency ratios computed for the U(NC)_1,2,4 molecules agree better with the observed values than those calculated for the U(CN)_1,2,4 isomers. Multiplets using mixed isotopic cyanogens reveal the stoichiometries of these products, and the band positions and quantum chemical calculations confirm the isocyanide bonding arrangements, which are 14 and 51 kJ/mol more stable than the cyanide isomers for UNC and U(NC)₂, respectively, and 62 kJ/mol for U(NC)₄ in the isolated gas phase at the CCSD(T)/CBS level. The studies further demonstrate that the isocyano nitrogen is a better π donor, so it interacts with U(VI) better than carbon. Although the higher isocyanides are more stable than the corresponding cyanides, U(NC)₅ and U(NC)₆ were not observed here most likely because unfavorable or endothermic routes are required for their production from U(NC)₄. The computed U–NC bond dissociation energies decrease from 581 kJ/mol for ⁴[UNC] to 168 kJ/mol for ¹[U(NC)₆ ]. The ionic nature of U(NC)_n decreases as the number of isocyano groups increases.

中文翻译：

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与（CN）₂形成UNC，U（NC）₂和U（NC）_4的激光烧蚀U原子反应：基质红外光谱和量子化学计算

激光烧蚀的U原子在4 K共沉积期间与过量的氩气和氖气中的（CN）₂反应，形成UNC，U（NC）₂和U（NC）₄作为主要的含铀产物，从它们的识别中可以看出使用被¹³ C和¹⁵ N取代的氰和来自量子化学计算的基体红外光谱。为U（NC）_1,2,4分子计算的^12/13 CN和C ^14/15 N同位素频率比与为U（CN）_1,2,4分子计算的观测值更好地符合观测值异构体。使用混合同位素氰多重揭示这些产品的化学计量，和频带位置和量子化学计算确认胩键合排列，它们是14和51千焦/摩尔以上为UNC和U（NC）的氰化物的异构体稳定₂分别，并且在CCSD（T）/ CBS级别的隔离气相中，U（NC）₄的浓度为62 kJ / mol 。研究进一步表明，异氰基氮是更好的π供体，因此它与U（VI）的相互作用比碳更好。尽管高级异氰酸酯比相应的氰化物更稳定，但此处极有可能未观察到U（NC）₅和U（NC）₆，因为从U（NC）_4的生产需要不利或吸热的路线。计算出的U–NC键解离能从⁴ [UNC]的581 kJ / mol降至¹ [U（NC）₆ ]的168 kJ / mol 。U（NC）_n的离子性质随异氰基基团数目的增加而降低。