β‑Diketiminate Germylene-Supported Pentafluorophenylcopper(I) and -silver(I) Complexes [LGe(Me)(CuC6F5)n]2 (n = 1, 2), LGe[C(SiMe3)N2]AgC6F5, and {LGe[C(SiMe3)N2](AgC6F5)2}2 (L = HC[C(Me)N-2,6‑iPr2C6H3]2): Synthesis and Structural Characterization

Reactions of LGeMe (L = HC­[C­(Me)­N-2,6-iPr2C6H3]2) with 0.25 or 0.5 equiv of (CuC6F5)4 gave the products [LGe­(Me)­CuC6F5]2 (1) and [LGe­(Me)­(CuC6F5)2]2 (2), respectively. In situ formed 1 reacted with 0.5 equiv of (CuC6F5)4 to give 2 on the basis of NMR (1H and 19F) spectral measurements. Conversely, 2 was converted into 1 by treatment with 2 equiv of LGeMe. Reactions of LGeC­(SiMe3)­N2 with 1 or 2 equiv of AgC6F5·MeCN produced the corresponding compounds LGe­[C­(SiMe3)­N2]­AgC6F5 (3) and {LGe­[C­(SiMe3)­N2]­(AgC6F5)2}2 (4). Similarly, 3 was converted into 4 by treatment with 1 equiv of AgC6F5·MeCN and 4 converted into 3 by reaction with 2 equiv of LGeC­(SiMe3)­N2. X-ray crystallographic studies showed that 1 contains a rhombically bridged (CuC6F5)2, while 2 has a chain-structurally aggregated (CuC6F5)4, both supported by LGeMe. Correspondingly, 3 showed a terminally bound AgC6F5 and 4 a chain-structurally aggregated (AgC6F5)4, both supported by LGeC­(SiMe3)­N2. Photophysical studies proved that the Ge–Cu metal–metalloid donor–acceptor bonding persists in solutions of 1 and 2 and Ge–Ag donor–acceptor bonding in solutions of 3 and 4 as a result of the clear migration of their emission bands compared to those of the corresponding starting materials. Low-temperature (−50 °C) 19F NMR spectral measurements detected dissociation of 1, 2, and 4 by the aggregation part of the CuC6F5 or AgC6F5 entities in solution. These results provide good support for pentafluorophenylcopper­(I) or -silver­(I) species having β-diketiminate germylene as a donor because of its remarkably electronic and steric character.