Nitridocyanometalates of Cr^V, Mn^V, and Mn^VI

Abstract

Reaction of [Cr V (N)(salen)]‚CH 3 NO 2 and [Mn V (N)(salen)] in dimethylformamide or a methanol/water mixture with an aqueous solution of NaCN and CsCl or [N(CH 3 ) 4 ]Cl at elevated temperatures affords in good yields, respectively, yellow microcrystalline compounds of Cs 2 Na[Cr V (N)(CN) 5 ] (1); [N(CH 3 ) 4 ] 2 Na[Cr V (N)(CN) 5 ]‚H 2 O (1a) and pink-violet crystals of Cs 2 Na[Mn V (N)(CN) 5 ] (4); and [N(CH 3 ) 4 ] 2 Na[Mn V (N)(CN) 5 ]‚H 2 O (4a). These six-coordinate nitridopentacyanometalates contain a terminal MtN unit and a labile cyano group in trans position. Recrystallization from water and addition of [PPh 4 ]Cl yields the five-coordinate species [PPh 4 ] 2 [M(N)(CN) 4 ]‚ 2H 2 O (M ) Cr V (2), Mn V (5)). From pyridine solutions of 2 and 5 the six-coordinate species [PPh 4 ] 2 [M(N)-(CN) 4 (py)]‚H 2 O‚py (M ) Cr V (3), Mn V (6)) crystallize. Complexes 1, 1a, 2, and 3 are paramagnetic (1.8 ( 0.1 µ B at 298 K; d 1 ) whereas 4, 4a, 5, and 6 have a low-spin d 2 ground state. Electrochemically, 5 can be reversibly one-electron-oxidized in CH 3 CN with formation of a relatively stable [Mn VI (N)(CN) 4 ]anion. Complexes 3, 5, and 6 have been characterized by single-crystal X-ray crystallography: 3 and 6 are isostructural and crystallize in the orthorhombic space group Pnma with a ) 17.336(3) (17.254(3)) Å , b ) 23.019(4) (22.873 (4)) Å, c ) 13.563(2) (13.490(2)) Å, V ) 5412 (2) (5324(2)) Å 3 , and Z ) 4 (4) (values in parentheses refer to 6); 5 crystallizes in the triclinic space group P1 h with a ) 12.050(1), b ) 12.310(1), c ) 16.685(2) Å, R ) 97.88(2)°, ) 109.33(2)°, γ ) 90.55(2)°, V ) 2309.4(4) Å 3 , and Z ) 2. The complexes have been characterized by 13 C and 15 N NMR, UV-vis, EPR, IR/Raman, and MCD spectroscopies.

An Iron Nitride Complex

“…Such short MN distances are typically observed for transition-metal complexes with triply bonded nitride ligands (M = Cr, Mn). [14][15][16][17][18][19] The Fe N distances in 4 R are also very similar to the XAS spectroscopically determined distances of the Fe IV complex [(PhB R P 3 )Fe(N)] (d(Fe N) = 1.51-1.55(2) , R = iPr, CH 2 -Cy) [8] by Peters and co-workers, and the octahedral Fe high-spin (S = 2) Fe II complexes. [20] Considering the trigonal coordination of the tris(carbene) chelator we suggest a ligand field, in which the paired electron is in an e orbital (e 3 a 1 1 e 2 ).…”

Structures, Electrochemical and Spectral Properties of a Series of [MnN(CN)3(diimine)]– Complexes

“…4 ] [24] and the corresponding dipyridyl derivative (1 equiv.). In all cases, small orange platelike crystals were obtained in quantitative yield, and all but those of 1(phen) were suitable for X-ray diffraction measurement.…”

Metal–Ligand Electron Transfer in 4d and 5d Group 9 Transition Metal Complexes with Pyridine, Diimine Ligands

“…While NO + /NO -ligands are well established, the consideration of a formal "N -" ligand is much less obvious. [30] We will first analyze the electronic structure in nitrosyl complex 3, which will be followed by a brief discussion of nitrido compound 1. Finally, we will put our findings into the general context of electron transfer in these Ir systems.…”