The structural chemistry of some osmium nitrosyl complexes

Abstract

The two complexes tribromo(nitrosyl)(diethylsulfide)(diethylsulfoxide)osmium(II), Os(NO)Br 3(Et 2S)- (Et 2SO) and dichloro(nitrosyl)bis(diethylphenylphosphine)(2-methoxyethanoate)osmium(II), Os(NO)- Cl 2(Et 2PPh) 2(CH 3OCH 2CH 2O), have been isolated during studies of photochemical reactions of platinum metal nitrosyl compounds. The molecular structures of these compounds have been determined by single crystal X-ray diffraction. The bright red crystals of Os(NO)Br 3(Et 2S)(Et 2SO) are monoclinic P2 1/ c; a=13.398(3), b=8.501(2), c=16.199(3) Å, β=105.69(5)°, V=1776.41(55) Å 3, Z=4. The structure was refined to a R factor of 0.0617 and a R w, of 0.0599. The complex is isostructural with the ruthenium analogue whose structure has been reported previously. The nitric oxide is coordinated in the linear manner (OsNO=174.3(29)°) and the diethylsulfoxide ligand is oxygen bound (OsO=2.074(17) Å) trans to the NO as suggested from its infrared spectrum ( v(SO)=940 cm −1). The pale orange crystals of Os(NO)Cl 2(Et 2PPh) 2(CH 3OCH 2CH 2O) are also monoclinic P2 1/ c; a=10.869(1), b=11.381(1), c=22.673(2) Å, β=102.17(10)°, V=2741.5(10) Å 3, z=4. The structure was refined to an R of 0.0482 and a R w of 0.0464. The diethylphenylphosphine ligands are coordinated in the trans-arrangement, and the OsP bond lengths are identical; 2.427(3), 2.428(3) Å. The nitric oxide is coordinated in the linear manner (OsNO=1.837(10) Å) and the 2-methoxyethanoate is coordinated trans to the nitrosyl (OsO=1.949(7) Å).