Air-stable fluorescent primary phosphine complexes of molybdenum and tungsten

Abstract

<p>Here we report a study on the reactivity of the fluorescent air-stable primary phosphine 8-((4-phosphino)phenyl)-4,4-dimethyl-1,3,5,7-tetramethyl-2,6-diethyl-4-bora-3a,4a-diaza-s-indacene <b>4</b> with [Mo(CO)₆], [W(CO)₆], [Mo(CO)₄(piperidine)] and [W(CO)₄(piperidine)] which yields the mono-phosphine [Mo(CO)₅(<b>4</b>)] <b>5</b>, [W(CO)₅(<b>4</b>)] <b>6</b> and di-phosphine <i>cis</i>-[Mo(CO)₄(<b>4</b>)₂] <i>cis</i>-<b>7</b> and <i>cis</i>-[W(CO)₄(<b>4</b>)₂] <i>cis</i>-<b>9</b> complexes as the predominant products. In addition to the characterization of these complexes by multinuclear NMR and IR spectroscopy, and mass spectrometry, the solid-state structures of <b>6</b> and <i>cis</i>-<b>7</b> have also been determined by single-crystal X-ray diffraction. The photophysical properties of the complexes show that the incorporation of the phosphorus ligand has a limited effect on the absorption and emission profile of the Bodipy core and that they retain similar quantum yields to their parent Bodipy dyes. Small quantities of the by-products <i>trans</i>-[Mo(CO)₄(<b>4</b>)₂] <i>trans</i>-<b>7</b>, <i>cis</i>-[Mo(CO)₄(piperidine)(<b>4</b>)] <i>cis</i>-<b>8</b> and <i>cis</i>-[W(CO)₄(piperidine)(<b>4</b>)] <i>cis</i>-<b>10</b> were also isolated and characterized.</p