Catalytic Production of Isocyanates via Orthogonal Atom and Group Transfers Employing a Shared Formal Group 6 M(II)/M(IV) Redox Cycle

Under
an atmosphere of CO, the Mo­(IV) imido complex Cp*Mo­[N­(iPr)­C­(Me)­N­(iPr)]­(NSiMe3) (Cp* = η5-C5Me5) (1) serves as a
catalyst for production of an isocyanate via metal-mediated nitrene
group transfer in benzene solution under mild conditions (55 °C,
10 psi) according to RN3 + CO → N2 +
RNCO. Mechanistic and structural studies support a catalytic cycle
for nitrene group transfer involving formal Mo­(II) monocarbonyl and
Mo­(IV) (κ2-C,N)-isocyanate intermediates.
These results complement an earlier finding that catalytic production
of isocyanates can alternatively proceed through oxygen-atom transfer
and an isomeric Mo­(IV) (κ2-C,O)-isocyanate
according to N2O + CNR → N2 + RNCO.

在CO的气氛下，Mo（IV）亚胺络合物Cp*Mo[N(iPr)C(Me)N(iPr)](NSiMe3)（Cp* = η5-C5Me5）（1）充当催化剂，在温和条件下（55°C，10 psi）于苯溶液中通过金属介导的亚胺基团转移反应生产异氰酸酯，反应式为RN3 + CO → N2 + RNCO。机制和结构研究表明，涉及形式Mo（II）单羰基和Mo（IV）（κ2-C,N）-异氰酸酯中间体的亚胺基团转移催化循环得到证实。这些结果补充了早期发现，即异氰酸酯的催化生产可以通过氧原子转移和异构的Mo（IV）（κ2-C,O）-异氰酸酯的生成进行，反应式为N2O + CNR → N2 + RNCO。