“Very mixed”-metal carbonyl clusters

Heterosite Effects in Novel Heteronuclear Clusters [Os2Ru(CO)11(PPh3)] and [Os2Ru(CO)10(2‐acetylpyridine‐N‐isopropylimine)]

“…After the addition of Br 2 , rapid removal of the heating bath is required in order to prevent the reaction of [Os 3 (CO) 12 (Br) 2 ] with additional Br 2 producing at this stage undesired [Os 2 (CO) 8 (Br) 2 ] that is known to transform into [Os 2 (CO) 6 (Br) 2 ] at elevated temperatures. [27] Similar oxidative addition of X 2 (X = Cl, Br, I) to [Ru 3 (CO) 12 ] was reported [28,29] to yield the mononuclear complex cis-[Ru(CO) 4 (X) 2 ] as the initial product, which reflects the increasing stability of the metal-metal bonds towards oxidation on descending the periodic table. Unfortunately, the synthetic strategy depicted in Scheme 1 could therefore not be applied for the synthesis of the isostructural cluster [Ru 2 Os(CO) 12 ].…”

“…[30] Visible irradiation of [Os 3 (CO) 12 12 ] by reduction with sodium in liquid ammonia [step (iii)]. [31] As [Ru(CO) 4 ] 2-is extremely air-and moisture-sensitive and readily converts to [Ru(CO) 4 H] -, the reduction of [Ru 3 -(CO) 12 ] was performed at reduced pressure (3 × 10 -4 Pa) on a high-vacuum line. After the completion of the reaction, the product must be dried extensively, as small traces of ammonia proved to react instantaneously with [Os 2 (CO) 8 12 ] by less than six equivalents of sodium.…”

“…This shortening is ascribed to increased π-back-bonding to the CO ligand, resulting from the presence of the σ-donating phosphorus ligand attached to the same metal and to the sterically induced lengthening of the Ru-Os2 bond trans to this CO group. [35] The Ru-Os bond lenghts [2.9147(2) 4 units, is reflected in the C ax -Os1-Os2-C ax dihedral angles. [35] Just like for the metal-metal bond lengths, the values for C1-Os1-Os2-C5 (3.5°) and C2-Os1-Os2-C6 (12 31 P{H} NMR and FD mass spectra of 2, indicating that the observed ratio between the Os 3 and Os 2 Ru phosphane-substituted clusters in the crystal structure is similar in the gas phase and in solution.…”

“…This trend points to the role of electronic effects apart from the expected steric influence. For, the differences in the metal-metal bond lengths should be smaller in the model 2a, as the steric interactions of the PH 3 ligand with the cis-CO group on the [44] Besides the crystal packing effects, not incorporated in the geometry optimisation of 2a, the twist of the M(CO) 4 units also depends on the selected computational basis set. [19] Figure 3.…”

“…[1][2][3][4] The interest in this type of clusters where at least one metal-metal bond con-that forms biradicals as the main primary photoproduct even in strongly coordinating solvents, zwitterion formation from the solvated lowest excited state is observed for the heterometallic cluster. This is concluded from time-resolved absorption studies in the microsecond time domain.…”