The Experts below are selected from a list of 192 Experts worldwide ranked by ideXlab platform
Brendan Twamley - One of the best experts on this subject based on the ideXlab platform.
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ring borylated 15 electron and 17 electron ansa Chromocene complexes their physical properties and molecular structures
Chemistry: A European Journal, 2007Co-Authors: Pamela J. Shapiro, Piet-jan Sinnema, Brendan Twamley, Philippe Perrotin, Ralph Zehnder, Peter H M Budzelaar, Hogni Weihe, Justin NairnAbstract:A detailed study of the thermal decomposition of the zwitterionic, ring-borylated ansa-Chromocene hydrido carbonyl complex [Cr(CO)H{Me(4)C(2)(C(5)H(4))[C(5)H(3)B(C(6)F(5))(3)]}] (2) is described. This complex is formed in the reaction between [Cr(CO){Me(4)C(2)(C(5)H(4))(2)}] (1) and B(C(6)F(5))(3) in toluene at -78 degrees C. Above -25 degrees C, 2 decomposes to a 50:50 mixture of the low-spin, 17e Cr(III) complexes [Cr(CO){Me(4)C(2)(C(5)H(4))[C(5)H(3)B(C(6)F(5))(3)]}] (3b) and [Cr(CO){Me(4)C(2)(C(5)H(4))(2)}][HB(C(6)F(5))(3)] (4). Carbon monoxide elimination from 3 b generates high-spin, 15 e [Cr{Me(4)C(2)(C(5)H(4))[C(5)H(3)B(C(6)F(5))(3)]}] (3a), which coordinates two other electron-donating ligands, such as xylyl isocyanide, PMe3, and PPh(2)Me to form the low-spin, 17 e electron complexes 3c, 3d, and 3e, respectively. High-spin, 15 e [Cr{Me(4)C(2)(C(5)H(4))(2)}][HB(C(6)F(5))(3)] (5) is generated by heating 3 b in toluene at 100 degrees C and periodically removing the evolved CO. Efforts to isolate more than a few X-ray quality crystals of 5 were thwarted by its tendency to form an insoluble precipitate (6) with the same molecular formula. Heating the solution of 5 at 120 degrees C results in its partial conversion (ca. 28 %) to 3a, thereby allowing the formation of 3a in yields as high as 74 % from the reaction between 1 and B(C(6)F(5))(3). The X-ray crystal structures of 3 b-e and 5 are described. Cyclic voltammetry measurements on 3 a-e reveal a dramatic reduction in the redox potentials of the complexes relative to their non-borylated analogues. DFT calculations show that this is due primarily to electrostatic stabilization of the oxidized species by the negatively charged borylate group. EPR and 19F NMR spectroscopy allow 3a to be distinguished from its Lewis base adducts 3 b-e and reveal the relative affinities of different Lewis bases for the chromium.
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in search of a versatile pathway to ansa Chromocene complexes synthesis and characterization of the highly unstable ansa Chromocene carbonyl complex me2c c5h4 2crco
Organometallics, 2007Co-Authors: Philippe Perrotin, Pamela J. Shapiro, And Mark Williams, Brendan TwamleyAbstract:In an effort to develop a general synthetic route to ansa-Chromocene complexes with diverse ligand frameworks, we investigated ansa-magnesocene compounds as an alternative, potentially more versati...
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ansa Chromocene complexes 2 isocyanide derivatives of cr ii and cr iii their syntheses x ray crystal structures and physical properties
Organometallics, 2006Co-Authors: Pamela J. Shapiro, Philippe Perrotin, Ralph Zehnder, David Min Jin Foo, Peter H M Budzelaar, Sharon Leitch, Brendan TwamleyAbstract:A variety of 18e ansa-Chromocene isocyanide complexes were prepared via ligand substitution on the carbonyl complexes. The relative π-accepting character of the different isocyanide ligands was eva...
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zwitterionic ring borylated ansa Chromocene complexes
Journal of the American Chemical Society, 2002Co-Authors: Piet-jan Sinnema, Pamela J. Shapiro, David Min Jin Foo, Brendan TwamleyAbstract:Ring borylation of [Me4C2(η5-C5H4)2CrCO] by B(C6F5)3 affords the zwitterionic complex {Me4(η5-C5H4)(η5-C4H3B(C6F5)3)}CrH(CO) (1), the first structurally characterized bent-metallocene complex of Cr(4+). This species decomposes thermally to the zwitterionic species {Me4(η5-C5H4)(η5-C4H3B(C6F5)3)}Cr (2) and the ionic species [Me4C2(η5-C5H4)2CrCO][HB(C6F5)3] (3). The molecular structure of 2 is also described.
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oxidation of an ansa Chromocene carbonyl complex
2002Co-Authors: Piet-jan Sinnema, Pamela J. Shapiro, Brendan TwamleyAbstract:This oral presentation described the intramolecular oxidation of an ansa-Chromocene carbonyl complex through the electrophilic addition of a borane to the cyclopentadienyl ring followed by transfer of a proton from the ring to the metal center. A variety of zwitterionic, ring-borylated ansa-Chromocene complexes were structurally and physically characterized. [Part of final report for DOE contract FG02-98ER45709.]
Pamela J. Shapiro - One of the best experts on this subject based on the ideXlab platform.
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ring borylated 15 electron and 17 electron ansa Chromocene complexes their physical properties and molecular structures
Chemistry: A European Journal, 2007Co-Authors: Pamela J. Shapiro, Piet-jan Sinnema, Brendan Twamley, Philippe Perrotin, Ralph Zehnder, Peter H M Budzelaar, Hogni Weihe, Justin NairnAbstract:A detailed study of the thermal decomposition of the zwitterionic, ring-borylated ansa-Chromocene hydrido carbonyl complex [Cr(CO)H{Me(4)C(2)(C(5)H(4))[C(5)H(3)B(C(6)F(5))(3)]}] (2) is described. This complex is formed in the reaction between [Cr(CO){Me(4)C(2)(C(5)H(4))(2)}] (1) and B(C(6)F(5))(3) in toluene at -78 degrees C. Above -25 degrees C, 2 decomposes to a 50:50 mixture of the low-spin, 17e Cr(III) complexes [Cr(CO){Me(4)C(2)(C(5)H(4))[C(5)H(3)B(C(6)F(5))(3)]}] (3b) and [Cr(CO){Me(4)C(2)(C(5)H(4))(2)}][HB(C(6)F(5))(3)] (4). Carbon monoxide elimination from 3 b generates high-spin, 15 e [Cr{Me(4)C(2)(C(5)H(4))[C(5)H(3)B(C(6)F(5))(3)]}] (3a), which coordinates two other electron-donating ligands, such as xylyl isocyanide, PMe3, and PPh(2)Me to form the low-spin, 17 e electron complexes 3c, 3d, and 3e, respectively. High-spin, 15 e [Cr{Me(4)C(2)(C(5)H(4))(2)}][HB(C(6)F(5))(3)] (5) is generated by heating 3 b in toluene at 100 degrees C and periodically removing the evolved CO. Efforts to isolate more than a few X-ray quality crystals of 5 were thwarted by its tendency to form an insoluble precipitate (6) with the same molecular formula. Heating the solution of 5 at 120 degrees C results in its partial conversion (ca. 28 %) to 3a, thereby allowing the formation of 3a in yields as high as 74 % from the reaction between 1 and B(C(6)F(5))(3). The X-ray crystal structures of 3 b-e and 5 are described. Cyclic voltammetry measurements on 3 a-e reveal a dramatic reduction in the redox potentials of the complexes relative to their non-borylated analogues. DFT calculations show that this is due primarily to electrostatic stabilization of the oxidized species by the negatively charged borylate group. EPR and 19F NMR spectroscopy allow 3a to be distinguished from its Lewis base adducts 3 b-e and reveal the relative affinities of different Lewis bases for the chromium.
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in search of a versatile pathway to ansa Chromocene complexes synthesis and characterization of the highly unstable ansa Chromocene carbonyl complex me2c c5h4 2crco
Organometallics, 2007Co-Authors: Philippe Perrotin, Pamela J. Shapiro, And Mark Williams, Brendan TwamleyAbstract:In an effort to develop a general synthetic route to ansa-Chromocene complexes with diverse ligand frameworks, we investigated ansa-magnesocene compounds as an alternative, potentially more versati...
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ansa Chromocene complexes 2 isocyanide derivatives of cr ii and cr iii their syntheses x ray crystal structures and physical properties
Organometallics, 2006Co-Authors: Pamela J. Shapiro, Philippe Perrotin, Ralph Zehnder, David Min Jin Foo, Peter H M Budzelaar, Sharon Leitch, Brendan TwamleyAbstract:A variety of 18e ansa-Chromocene isocyanide complexes were prepared via ligand substitution on the carbonyl complexes. The relative π-accepting character of the different isocyanide ligands was eva...
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zwitterionic ring borylated ansa Chromocene complexes
Journal of the American Chemical Society, 2002Co-Authors: Piet-jan Sinnema, Pamela J. Shapiro, David Min Jin Foo, Brendan TwamleyAbstract:Ring borylation of [Me4C2(η5-C5H4)2CrCO] by B(C6F5)3 affords the zwitterionic complex {Me4(η5-C5H4)(η5-C4H3B(C6F5)3)}CrH(CO) (1), the first structurally characterized bent-metallocene complex of Cr(4+). This species decomposes thermally to the zwitterionic species {Me4(η5-C5H4)(η5-C4H3B(C6F5)3)}Cr (2) and the ionic species [Me4C2(η5-C5H4)2CrCO][HB(C6F5)3] (3). The molecular structure of 2 is also described.
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oxidation of an ansa Chromocene carbonyl complex
2002Co-Authors: Piet-jan Sinnema, Pamela J. Shapiro, Brendan TwamleyAbstract:This oral presentation described the intramolecular oxidation of an ansa-Chromocene carbonyl complex through the electrophilic addition of a borane to the cyclopentadienyl ring followed by transfer of a proton from the ring to the metal center. A variety of zwitterionic, ring-borylated ansa-Chromocene complexes were structurally and physically characterized. [Part of final report for DOE contract FG02-98ER45709.]
Ralph Zehnder - One of the best experts on this subject based on the ideXlab platform.
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ring borylated 15 electron and 17 electron ansa Chromocene complexes their physical properties and molecular structures
Chemistry: A European Journal, 2007Co-Authors: Pamela J. Shapiro, Piet-jan Sinnema, Brendan Twamley, Philippe Perrotin, Ralph Zehnder, Peter H M Budzelaar, Hogni Weihe, Justin NairnAbstract:A detailed study of the thermal decomposition of the zwitterionic, ring-borylated ansa-Chromocene hydrido carbonyl complex [Cr(CO)H{Me(4)C(2)(C(5)H(4))[C(5)H(3)B(C(6)F(5))(3)]}] (2) is described. This complex is formed in the reaction between [Cr(CO){Me(4)C(2)(C(5)H(4))(2)}] (1) and B(C(6)F(5))(3) in toluene at -78 degrees C. Above -25 degrees C, 2 decomposes to a 50:50 mixture of the low-spin, 17e Cr(III) complexes [Cr(CO){Me(4)C(2)(C(5)H(4))[C(5)H(3)B(C(6)F(5))(3)]}] (3b) and [Cr(CO){Me(4)C(2)(C(5)H(4))(2)}][HB(C(6)F(5))(3)] (4). Carbon monoxide elimination from 3 b generates high-spin, 15 e [Cr{Me(4)C(2)(C(5)H(4))[C(5)H(3)B(C(6)F(5))(3)]}] (3a), which coordinates two other electron-donating ligands, such as xylyl isocyanide, PMe3, and PPh(2)Me to form the low-spin, 17 e electron complexes 3c, 3d, and 3e, respectively. High-spin, 15 e [Cr{Me(4)C(2)(C(5)H(4))(2)}][HB(C(6)F(5))(3)] (5) is generated by heating 3 b in toluene at 100 degrees C and periodically removing the evolved CO. Efforts to isolate more than a few X-ray quality crystals of 5 were thwarted by its tendency to form an insoluble precipitate (6) with the same molecular formula. Heating the solution of 5 at 120 degrees C results in its partial conversion (ca. 28 %) to 3a, thereby allowing the formation of 3a in yields as high as 74 % from the reaction between 1 and B(C(6)F(5))(3). The X-ray crystal structures of 3 b-e and 5 are described. Cyclic voltammetry measurements on 3 a-e reveal a dramatic reduction in the redox potentials of the complexes relative to their non-borylated analogues. DFT calculations show that this is due primarily to electrostatic stabilization of the oxidized species by the negatively charged borylate group. EPR and 19F NMR spectroscopy allow 3a to be distinguished from its Lewis base adducts 3 b-e and reveal the relative affinities of different Lewis bases for the chromium.
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polynuclear metallocene complexes incorporating ansa Chromocene and ferrocene units
2006Co-Authors: Ralph ZehnderAbstract:Novel bimetallic and trimetallic complexes containing ansa-Chromocene units have have been synthesized by a ligand substitution approach. The carbonyl ligands of the corresponding ansa-Chromocene carbonyl complexes were substituted by the mono- and diisocyanide species ferrocenylisocyanide, ferrocenyldiisocyandie, and 1,4-phenylene diisocyanide in order to form polymetallic complexes that might exhibit mixed valence behavior. The heteronuclear complexes containing a ferrocene unit show a remarkable stability against thermolysis and photolysis. Cyrstallographic data show that the C-N-C bond angles and Cr-C bond distances of these species follow the trend of other ansa-Chromocene isocyanides that show a moderate dependence of the Cr 2+/3+ redox potential on the substituents of the isocyanide groups. In contrast, the heteronuclear complexes do not follow such a trend in respect to their electronic properties. Interestingly, these complexes can modulate the electron density at the Cr metal centers, which enables them to keep their redox potentials constant. Neuartige ansa-Chromocenkomplexe mit zwei bzw. drei Metallzentren wurden mittels Ligandensubtitution synthetisiert. Die Carbonyl-Liganden der entsprechenden ansa-Chromocencarbonylkomplexe wurden von den Isocyanidderivaten Ferrocenisocyanid, Ferrocendiisocyanid und 1,4-Phenyldiisocyanid substituiert, um mehrkernige Komplexe zu erhalten, die eventuell gemischtvalente Eigenschaften aufweisen konnten. Die heteronuklearen ansa-Chromocenkomplexe mit einer Ferroceneinheit zeigen eine beachtliche Stabilitat in Bezug auf Photolyse und Thermolyse. Kristallografische Daten zeigen, dass die C-N-C Bindungswinkel und Cr-C Bindungslangen dem Trend anderer Isocyanide folgen, die eine gewisse Abhangigkeit des Cr 2+/3+ Redoxpotentials von der Art der Substituenten an den Isocyanidgruppen aufweisen. Im Kontrast dazu folgen die heteronuklearen Komplexe nicht solch einem Trend in Bezug auf ihre elektronischen Eigenschaften. Interessanterweise konnen diese Komplexe die Elektronendichte an den Cr Metallzentren regulieren, was ihnen ermoglicht, ihre Redoxpotentiale konstant zu halten.
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ansa Chromocene complexes 2 isocyanide derivatives of cr ii and cr iii their syntheses x ray crystal structures and physical properties
Organometallics, 2006Co-Authors: Pamela J. Shapiro, Philippe Perrotin, Ralph Zehnder, David Min Jin Foo, Peter H M Budzelaar, Sharon Leitch, Brendan TwamleyAbstract:A variety of 18e ansa-Chromocene isocyanide complexes were prepared via ligand substitution on the carbonyl complexes. The relative π-accepting character of the different isocyanide ligands was eva...
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synthesis and properties of a new heterotriinuclear ansa Chromocene
2002Co-Authors: Ralph Zehnder, Brendan Twamley, David Min Jin Foo, Pamela J. ShapiroAbstract:In this oral presentation, the synthesis and the physical and structural characterization of bimetallic and trimetallic complexes containing ansa-Chromocene units bound to ferrocenyl isocyanide and 1,1'-diisocyanoferrocene units were described. [Part of final report for DOE contract FG02-98ER45709.]
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synthesis and properties of a new heterobinuclear ansa Chromocene
2002Co-Authors: Ralph Zehnder, Brendan Twamley, David Min Jin Foo, Pamela J. ShapiroAbstract:In this oral presentation, the synthesis and the physical and structural characterization of bimetallic and trimetallic complexes containing ansa-Chromocene units bound to ferrocenyl isocyanide and 1,1'-diisocyanoferrocene units were described. [Part of final report for DOE contract FG02-98ER45709.]
Piet-jan Sinnema - One of the best experts on this subject based on the ideXlab platform.
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ring borylated 15 electron and 17 electron ansa Chromocene complexes their physical properties and molecular structures
Chemistry: A European Journal, 2007Co-Authors: Pamela J. Shapiro, Piet-jan Sinnema, Brendan Twamley, Philippe Perrotin, Ralph Zehnder, Peter H M Budzelaar, Hogni Weihe, Justin NairnAbstract:A detailed study of the thermal decomposition of the zwitterionic, ring-borylated ansa-Chromocene hydrido carbonyl complex [Cr(CO)H{Me(4)C(2)(C(5)H(4))[C(5)H(3)B(C(6)F(5))(3)]}] (2) is described. This complex is formed in the reaction between [Cr(CO){Me(4)C(2)(C(5)H(4))(2)}] (1) and B(C(6)F(5))(3) in toluene at -78 degrees C. Above -25 degrees C, 2 decomposes to a 50:50 mixture of the low-spin, 17e Cr(III) complexes [Cr(CO){Me(4)C(2)(C(5)H(4))[C(5)H(3)B(C(6)F(5))(3)]}] (3b) and [Cr(CO){Me(4)C(2)(C(5)H(4))(2)}][HB(C(6)F(5))(3)] (4). Carbon monoxide elimination from 3 b generates high-spin, 15 e [Cr{Me(4)C(2)(C(5)H(4))[C(5)H(3)B(C(6)F(5))(3)]}] (3a), which coordinates two other electron-donating ligands, such as xylyl isocyanide, PMe3, and PPh(2)Me to form the low-spin, 17 e electron complexes 3c, 3d, and 3e, respectively. High-spin, 15 e [Cr{Me(4)C(2)(C(5)H(4))(2)}][HB(C(6)F(5))(3)] (5) is generated by heating 3 b in toluene at 100 degrees C and periodically removing the evolved CO. Efforts to isolate more than a few X-ray quality crystals of 5 were thwarted by its tendency to form an insoluble precipitate (6) with the same molecular formula. Heating the solution of 5 at 120 degrees C results in its partial conversion (ca. 28 %) to 3a, thereby allowing the formation of 3a in yields as high as 74 % from the reaction between 1 and B(C(6)F(5))(3). The X-ray crystal structures of 3 b-e and 5 are described. Cyclic voltammetry measurements on 3 a-e reveal a dramatic reduction in the redox potentials of the complexes relative to their non-borylated analogues. DFT calculations show that this is due primarily to electrostatic stabilization of the oxidized species by the negatively charged borylate group. EPR and 19F NMR spectroscopy allow 3a to be distinguished from its Lewis base adducts 3 b-e and reveal the relative affinities of different Lewis bases for the chromium.
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zwitterionic ring borylated ansa Chromocene complexes
Journal of the American Chemical Society, 2002Co-Authors: Piet-jan Sinnema, Pamela J. Shapiro, David Min Jin Foo, Brendan TwamleyAbstract:Ring borylation of [Me4C2(η5-C5H4)2CrCO] by B(C6F5)3 affords the zwitterionic complex {Me4(η5-C5H4)(η5-C4H3B(C6F5)3)}CrH(CO) (1), the first structurally characterized bent-metallocene complex of Cr(4+). This species decomposes thermally to the zwitterionic species {Me4(η5-C5H4)(η5-C4H3B(C6F5)3)}Cr (2) and the ionic species [Me4C2(η5-C5H4)2CrCO][HB(C6F5)3] (3). The molecular structure of 2 is also described.
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oxidation of an ansa Chromocene carbonyl complex
2002Co-Authors: Piet-jan Sinnema, Pamela J. Shapiro, Brendan TwamleyAbstract:This oral presentation described the intramolecular oxidation of an ansa-Chromocene carbonyl complex through the electrophilic addition of a borane to the cyclopentadienyl ring followed by transfer of a proton from the ring to the metal center. A variety of zwitterionic, ring-borylated ansa-Chromocene complexes were structurally and physically characterized. [Part of final report for DOE contract FG02-98ER45709.]
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Isolation of a Stable ansa-Chromocene(III) Carbonyl Cation and Characterization of a Transient, Cationic ansa-Chromocene(IV) Carbonyl Hydride
Organometallics, 2002Co-Authors: David M. Foo, Piet-jan Sinnema, Brendan Twamley, Pamela J. ShapiroAbstract:Protonation of the metal occurs upon reaction of Me4C2(C5H4)2CrCO with [H(Et2O)2][B(3,5-(CF3)2C6H3)4] at −70 °C in thf-d8. The diamagnetic Cr(IV) hydride intermediate was characterized by 1H NMR spectroscopy. Its decomposition to a paramagnetic product mixture upon warming to room temperature is accompanied by the evolution of 0.5 equiv of gas that is 54% H2 and 46% CO. Crystals of the borate salt of the 17e- ansa-chromocenium carbonyl cation [Me4C2(C2H4)2CrCO]+ were isolated from the product mixture for a molecular structure determination.
David Min Jin Foo - One of the best experts on this subject based on the ideXlab platform.
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ansa Chromocene complexes 2 isocyanide derivatives of cr ii and cr iii their syntheses x ray crystal structures and physical properties
Organometallics, 2006Co-Authors: Pamela J. Shapiro, Philippe Perrotin, Ralph Zehnder, David Min Jin Foo, Peter H M Budzelaar, Sharon Leitch, Brendan TwamleyAbstract:A variety of 18e ansa-Chromocene isocyanide complexes were prepared via ligand substitution on the carbonyl complexes. The relative π-accepting character of the different isocyanide ligands was eva...
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zwitterionic ring borylated ansa Chromocene complexes
Journal of the American Chemical Society, 2002Co-Authors: Piet-jan Sinnema, Pamela J. Shapiro, David Min Jin Foo, Brendan TwamleyAbstract:Ring borylation of [Me4C2(η5-C5H4)2CrCO] by B(C6F5)3 affords the zwitterionic complex {Me4(η5-C5H4)(η5-C4H3B(C6F5)3)}CrH(CO) (1), the first structurally characterized bent-metallocene complex of Cr(4+). This species decomposes thermally to the zwitterionic species {Me4(η5-C5H4)(η5-C4H3B(C6F5)3)}Cr (2) and the ionic species [Me4C2(η5-C5H4)2CrCO][HB(C6F5)3] (3). The molecular structure of 2 is also described.
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synthesis and properties of a new heterotriinuclear ansa Chromocene
2002Co-Authors: Ralph Zehnder, Brendan Twamley, David Min Jin Foo, Pamela J. ShapiroAbstract:In this oral presentation, the synthesis and the physical and structural characterization of bimetallic and trimetallic complexes containing ansa-Chromocene units bound to ferrocenyl isocyanide and 1,1'-diisocyanoferrocene units were described. [Part of final report for DOE contract FG02-98ER45709.]
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synthesis and properties of a new heterobinuclear ansa Chromocene
2002Co-Authors: Ralph Zehnder, Brendan Twamley, David Min Jin Foo, Pamela J. ShapiroAbstract:In this oral presentation, the synthesis and the physical and structural characterization of bimetallic and trimetallic complexes containing ansa-Chromocene units bound to ferrocenyl isocyanide and 1,1'-diisocyanoferrocene units were described. [Part of final report for DOE contract FG02-98ER45709.]
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ansa Chromocene complexes 1 synthesis and characterization of cr ii carbonyl and tert butyl isocyanide complexes
Organometallics, 2000Co-Authors: Gilbert J Matare, Pamela J. Shapiro, Ralph Zehnder, David Min Jin Foo, Kevin M Kane, Marion Wagener, Tom Concolino, Arnold L RheingoldAbstract:ansa-Calcocene compounds are effective reagents for the synthesis of ansa-Chromocene complexes from CrCl{sub 2} in the presence of a trapping ligand such as carbon monoxide or an isonitrile. A variety of ansa-Chromocene carbonyl and tert-butyl isocyanide complexes have been prepared in this manner in high yields. The X-ray crystal structure of one of these complexes, [trans-1,2-(3,4-(CH{sub 3}O){sub 2}C{sub 6}H{sub 3}){sub 2}C{sub 2}H{sub 2}{l_brace}{eta}{sup 5}-C{sub 5}H{sub 4}{r_brace}{sub 2}]CrCO, is described. Electrochemical studies on these complexes show that the isonitrile derivatives are more easily oxidized than the carbonyl derivatives. Preliminary examination of the reactivity of these complexes indicates that the nature of the substitution along the ethanediyl ansa-bridge influences the relative stabilities of the carbonyl complexes to oxidation in air, the ease with which the carbonyl ligands undergo substitution with tert-butyl isocyanide, and the relative sensitivities of the tert-butyl isocyanide adducts to photodecomposition. The ansa-bridge substitution also appears to influence the ability of the complexes to undergo structural changes, such as ring slippage, as revealed in their cyclic voltammograms.