The higher acidity of the silanol groups in 9b in combination with bulky aryl groups on silicon does not change the outcome either (Scheme 3). A monomeric complex of type A, as initially targeted, has neither been observed nor isolated; its heterodimerization must hence be fast and facile. The constitution of the resulting heterodimeric complex 14 was again ascertained by X-ray crystallography (Fig- ). With 2.3440(3) Å, the MoMo bond of 14 is the longest triple bond between two unbridged Mo(+3) centers with CN = 4 each (CN = coordination number) documented in the literature (Figure ). Scheme 3. Heterodimer with a trisilanolate podand cap Table . Mo NMR shifts ([D8]-toluene, 333 K (unless stated otherwise)) and MoMo distances of selected dimeric complexes.