Tetrakis[μ-(6-methyl-2-pyridinolato)]dirhodium

The synthesis of mixed-valence dirhodium carbonyl complexes, and the X-ray crystal structures of [{Rh(CO)(PPh3)(µ-RNNNR)}2] and [{Rh(CO)(PPh3)(µ-RNNNR)}2][PF6](R =p-tolyl)

“…Electron loss, to give the stable, paramagnetic monodirhodium complexes ,l particularly those depending on cations [ Rh2(C0)4-,( PPh3),( P-RNXNR)~] +, is accompanied metal-metal bond formation and cleavage, and in the by an increase in the rhodium-rhodium bond order and chemistry of mixed-valence compounds,2 prompts us to report activation towards carbonyl substitution. on the one-electron oxidation of [Rh2(CO) 4 diffusion-controlled one-electron steps (E" = 0.84, 1.43, and 1.78 V vs. s.c.e., in CH2C12, at a platinum bead electrode).…”

“…The cyclic voltammogram of (4) shows a reversible oneelectron oxidation wave (E" = 0.20 V) and a second, irreversible process at ca. 1.2 V; reaction with [Fe(y-C5H5)2][PF6] gives the paramagnetic tricarbonyl [ Rh2(C0)3(PPh3) { p-PhNC(Me)NPh>,][PF6] (5), orangebrown, 52%, q(C0) (CH2C12) 2099s, 2054s, and 2039sh cm-'.…”

Characterizations of Novel Binuclear Transition Metal Polynitrogen Compounds: M₂(N₅)₄ (M=Co, Rh and Ir)

“…The Rh-Rh bond (axis) distances of structure 5-2 is 2.493 Å (MPW1PW91) or 2.522 Å (B3LYP), which is nearly equal to the known experimental Rh-Rh bond distances (2.523 Å) of Rh 2 (MeCO 2 ) 2 ({CF 3 CO} 2 CH) 2 [50,51]. The unique Rh-N bond distances fall in the range of 1.845 to 1.935 Å (MPW1PW91) or 1.870 to 1.958 Å (B3LYP), which is slight shorter than the experimental Rh-N bond distance (~2.043 Å) of Rh 2 (C 6 H 6 NO) 4 [49], implying there are strong bond interactions between rhodium atoms and nitrogen atoms in The third energetically low-lying isomer of Rh 2 (N 5 ) 4 structure 5-3 lies above 5-1 by 50.1 kcal/mol (MPW1PW91) or 45.4 kcal/mol (B3LYP), Structure 5-3 is a C 2v structure (with two bridging η 2 -µ-N 5 groups and two terminal η 2 -N 5 groups) and has all real harmonic vibrational frequencies (Figure 2). The unique Rh-N bond distances to the bridging pentazole groups is 2.001 Å (MPW1PW91) or 2.022 Å (B3LYP) and to the terminal η 2 -N 5 rings is 2.075 Å (MPW1PW91) or 2.098 Å (B3LYP).…”

“…However, the Rh 2 (C 6 H 6 NO) 4 with four bridging-ring ligands has a very shorter Rh-Rh bond distance (2.359 Å) [49], whatever configuration and Rh-Rh bond distance of the structure 5-1 is very close to that of Rh 2 (C 6 H 6 NO) 4 , implying that the four bridging-ring ligands play an important role in stabilizing these two compounds and significantly shorten the Rh-Rh bond distance. The unique Rh-N distances is 2.063 Å (MPW1PW91) or 2.088 Å (B3LYP), which is very close to the experimental Rh-N bond distance (~2.043 Å) of Rh 2 (C 6 H 6 NO) 4 [49], and the N-N bond distances fall in the range of 1.292 to 1.328 Å (MPW1PW91) or 1.300 to The second lowest energy structure for Rh 2 (N 5 ) 4 , namely 5-2 structure (η 1 -N 5 )Rh 2 (η 2 -µ-N 5 ) 3 , a C s aircraft-like conformation with all real vibrational frequencies (Figure 2), is predicted to lie 44.3 kcal/mol (MPW1PW91) or 40.9 kcal/mol (B3LYP) above the global minimum 5-1. The Rh-Rh bond (axis) distances of structure 5-2 is 2.493 Å (MPW1PW91) or 2.522 Å (B3LYP), which is nearly equal to the known experimental Rh-Rh bond distances (2.523 Å) of Rh 2 (MeCO 2 ) 2 ({CF 3 CO} 2 CH) 2 [50,51].…”