Large organic molecules and metal complexes are promising candidates for organic electronics, optoelectronics, and spintronics, with interfaces to metals being critical. Clean preparation in ultra-high vacuum (UHV) is ideal, but many systems are fragile and cannot be thermally sublimed. This study details the preparation of thin films of the metallacrown Cu(II)[12-MCCu(II)N(Shi)-4] (short: CuCu4) from the liquid phase using electrospray injection (ESI) and, in particular, liquid injection (LI). Both methods produce films with intact CuCu4 complexes, but they differ in the amount of co-adsorbed solvent molecules. Enhancements using an argon stream perpendicular to the molecular beam significantly reduce these contaminants. An additional effect occurs due to the counterions (HNEt3)2 of CuCu4. They are co-deposited by LI, but not by ESI. The advantages and limitations of the LI method are discussed in detail. The CuCu4 films prepared by different methods were analyzed with infrared (IR) spectroscopy, ultraviolet and X-ray photoelectron spectroscopy (UPS, XPS), and scanning tunneling microscopy (STM). For thicker films, ex situ and in situ prepared CuCu4 films to exhibit similar properties, but for studying interface effects or ultrathin films, in situ preparation is necessary.
