TY - JOUR
T1 - Photochemical Properties and X-ray Structural Characterization of a Tetranuclear Bimetallic Complex
T2 - [Rh2(TM4-bridge)4Mn2(CO)10](PF6)2.2(CH3)2CO (TM4-bridge = 2,5-Dimethyl-2,5-diisocyanohexane)
AU - Bohling, David A.
AU - Gill, Thomas P.
AU - Mann, Kent R.
PY - 1981/1
Y1 - 1981/1
N2 - The sunlight irradiation of Mn2(CO)10 in the presence of Rh2(TM4-bridge)4PF6 (TM4-bridge = 2,5-dimethyl-2,5-diisocyanohexane) in acetone solution yields the mixed-metal tetranuclear compound [Rh2(TM4-bridge)4Mn2(CO)10]- (PF6)2.2(CH3)2CO. The dark green crystals obtained from acetone/hexane crystallize in the space group Pna2 (No. 33) (a = 18.265 (11), b = 23.185 (7), c = 17.836 (4) Á; Z - 4, p(calcd) = 1.391 (1), p(obsd) = 1.41 (2) g/cm3). The structure is composed of tetranuclear [(CO)5MnRh2(TM4-bridge)4Mn(CO)5]2+ cations having approximate D2d symmetry, PF6 anions, and two acetone molecules of crystallization per formula unit. The geometry about each Mn and Rh atom is approximately pseudooctahedral. The RhRh bond length is 2.922 (2) Á while the two RhMn bonds are 2.905 (5) and 2.883 (4) Á. The quantum yields for the formation of [Rh2(TM4-bridge)Mn2(CO)10]2+ in acetone solution (2.6 X 10-3 M in Mn2(CO)10 and 1.2 x 10-3 M in Rh2(TM4-bridge)42+) were measured by irradiation with 405- and 546-nm light. At 405 nm, the quantum yield for the formation of [Rh2(TM4-bridge)4Mn2(CO)10]2+ (a wavelength corresponding to absorbance by Mn2(CO)10) was Ø= 0.20 (1). At 546 nm, where greater than 99% of the light is absorbed by Rh2- (TM4-bridge)42+, the quantum yield was found to be Ø ~ 3 (1) X 10-4, almost 3 orders of magnitude smaller than at 405 nm. These data are tentatively interpreted in terms of the generation of Mn(CO)5 radicals which are efficiently collected by the Rh2(TM4-bridge)42+ ion present in solution. The [Rh2(TM4-bridge)4Mn2(CO)10]2+ ion was found to be relatively stable in degassed acetone solution under photolysis with a 4-mW HeNe laser (Ø decompaction ~ 5 (2) X 10-5). In the presence of oxygen, however, irradiation of the complex regenerates Rh2(TM4-bridge)42+ (Ø decomposition ~ 2 (1) X 10-2) and an undetermined Mn complex. These properties are discussed in terms of simple molecular orbital theory.
AB - The sunlight irradiation of Mn2(CO)10 in the presence of Rh2(TM4-bridge)4PF6 (TM4-bridge = 2,5-dimethyl-2,5-diisocyanohexane) in acetone solution yields the mixed-metal tetranuclear compound [Rh2(TM4-bridge)4Mn2(CO)10]- (PF6)2.2(CH3)2CO. The dark green crystals obtained from acetone/hexane crystallize in the space group Pna2 (No. 33) (a = 18.265 (11), b = 23.185 (7), c = 17.836 (4) Á; Z - 4, p(calcd) = 1.391 (1), p(obsd) = 1.41 (2) g/cm3). The structure is composed of tetranuclear [(CO)5MnRh2(TM4-bridge)4Mn(CO)5]2+ cations having approximate D2d symmetry, PF6 anions, and two acetone molecules of crystallization per formula unit. The geometry about each Mn and Rh atom is approximately pseudooctahedral. The RhRh bond length is 2.922 (2) Á while the two RhMn bonds are 2.905 (5) and 2.883 (4) Á. The quantum yields for the formation of [Rh2(TM4-bridge)Mn2(CO)10]2+ in acetone solution (2.6 X 10-3 M in Mn2(CO)10 and 1.2 x 10-3 M in Rh2(TM4-bridge)42+) were measured by irradiation with 405- and 546-nm light. At 405 nm, the quantum yield for the formation of [Rh2(TM4-bridge)4Mn2(CO)10]2+ (a wavelength corresponding to absorbance by Mn2(CO)10) was Ø= 0.20 (1). At 546 nm, where greater than 99% of the light is absorbed by Rh2- (TM4-bridge)42+, the quantum yield was found to be Ø ~ 3 (1) X 10-4, almost 3 orders of magnitude smaller than at 405 nm. These data are tentatively interpreted in terms of the generation of Mn(CO)5 radicals which are efficiently collected by the Rh2(TM4-bridge)42+ ion present in solution. The [Rh2(TM4-bridge)4Mn2(CO)10]2+ ion was found to be relatively stable in degassed acetone solution under photolysis with a 4-mW HeNe laser (Ø decompaction ~ 5 (2) X 10-5). In the presence of oxygen, however, irradiation of the complex regenerates Rh2(TM4-bridge)42+ (Ø decomposition ~ 2 (1) X 10-2) and an undetermined Mn complex. These properties are discussed in terms of simple molecular orbital theory.
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U2 - 10.1021/ic50215a039
DO - 10.1021/ic50215a039
M3 - Article
AN - SCOPUS:0003416916
SN - 0020-1669
VL - 20
SP - 194
EP - 199
JO - Inorganic chemistry
JF - Inorganic chemistry
IS - 1
ER -