Transition metal-siloxide complexes; synthesis, structure and application to catalysis

Mechanistic Significance of the Si–O–Pd Bond in the Palladium-Catalyzed Cross-Coupling Reactions of Arylsilanolates

“…The only complex that showed a slightly elongated Pd–O bond length is the dppf-derived adduct 10 (2.085 Å), which may be a consequence of the more electron-deficient trifluoromethyl-substituted aryl ring. The Si(1)–O(1) bond lengths of each aryl­palladium­(II) aryl­silanol­ate complex are all consistent with those of previously reported metal silanolate complexes . The trans influence of the aryl group is significant, as the P(2)–Pd(1) bond (2.343 and 2.316 Å) is much longer than the P(1)–Pd(1) bond (2.216 and 2.199 Å).…”

Mechanistic Significance of the Si–O–Pd Bond in the Palladium-Catalyzed Cross-Coupling Reactions of Arylsilanolates

“…The only complex that showed a slightly elongated Pd–O bond length is the dppf-derived adduct 10 (2.085 Å), which may be a consequence of the more electron-deficient trifluoromethyl-substituted aryl ring. The Si(1)–O(1) bond lengths of each aryl­palladium­(II) aryl­silanol­ate complex are all consistent with those of previously reported metal silanolate complexes . The trans influence of the aryl group is significant, as the P(2)–Pd(1) bond (2.343 and 2.316 Å) is much longer than the P(1)–Pd(1) bond (2.216 and 2.199 Å).…”

Prediction of 89Y NMR Chemical Shifts in Organometallic Complexes with Density Functional Theory

“…If the average of −24 ppm is used as a starting point for the contribution of a OPR 3 group (R = aryl or alkyl), then the value observed for Y(OSiPh 3 ) 3 (OP n -Bu 3 ) 2 implies that +90 ppm is an appropriate value for OSiPh 3 . This value is consistent with the expectation that alkoxides, with an average contribution of +56 ppm, are better σ-donors than are the corresponding aryl silyloxides 2 Empirical Group Contributions to 89 Y NMR Chemical Shift a groupcontribution (ppm)ref C 5 Me 5 −100 51 OPR 3 (R = aryl or alkyl) −24 this work OCMe 2 i -Pr +12 51 OCMeEt i -Pr +15 51 OCEt 3 +16 51 O-2,6- t -Bu 2 C 6 H 3 +56 51 O-2,6- t -Bu 2 C 6 H 2 -4-Me +57 51 OSiPh 3 +90 this work N(SiMe 3 ) 2 +190 51 CH(SiMe 3 ) 2 +298 51 a Aromatic solvent (benzene or toluene). …”

Bis(tetrahydrofuran-κO)tris(tri-tert-butoxysiloxy)chromium(III)

“…The Cr-O(siloxide) bond lengths are similar to those reported for Cr[OSi(O t Bu) 3 ] 3 -(HNEt 2 ) 2 (Terry et al, 1993). The Cr-O-Si angles and Si-O bond lengths are within the ranges expected in transitionmetal-siloxide complexes (Marciniec & Maciejewski, 2001;Chandrasekhar et al, 2004).…”

Mechanistic Significance of the Si–O–Pd Bond in the Palladium-Catalyzed Cross-Coupling Reactions of Arylsilanolates

“…The only complex that showed a slightly elongated Pd–O bond length is the dppf-derived adduct 10 (2.085 Å), which may be a consequence of the more electron-deficient trifluoromethyl-substituted aryl ring. The Si(1)–O(1) bond lengths of each aryl­palladium­(II) aryl­silanol­ate complex are all consistent with those of previously reported metal silanolate complexes . The trans influence of the aryl group is significant, as the P(2)–Pd(1) bond (2.343 and 2.316 Å) is much longer than the P(1)–Pd(1) bond (2.216 and 2.199 Å).…”

Prediction of 89Y NMR Chemical Shifts in Organometallic Complexes with Density Functional Theory

“…If the average of −24 ppm is used as a starting point for the contribution of a OPR 3 group (R = aryl or alkyl), then the value observed for Y(OSiPh 3 ) 3 (OP n -Bu 3 ) 2 implies that +90 ppm is an appropriate value for OSiPh 3 . This value is consistent with the expectation that alkoxides, with an average contribution of +56 ppm, are better σ-donors than are the corresponding aryl silyloxides 2 Empirical Group Contributions to 89 Y NMR Chemical Shift a groupcontribution (ppm)ref C 5 Me 5 −100 51 OPR 3 (R = aryl or alkyl) −24 this work OCMe 2 i -Pr +12 51 OCMeEt i -Pr +15 51 OCEt 3 +16 51 O-2,6- t -Bu 2 C 6 H 3 +56 51 O-2,6- t -Bu 2 C 6 H 2 -4-Me +57 51 OSiPh 3 +90 this work N(SiMe 3 ) 2 +190 51 CH(SiMe 3 ) 2 +298 51 a Aromatic solvent (benzene or toluene). …”

Bis(tetrahydrofuran-κO)tris(tri-tert-butoxysiloxy)chromium(III)

“…The Cr-O(siloxide) bond lengths are similar to those reported for Cr[OSi(O t Bu) 3 ] 3 -(HNEt 2 ) 2 (Terry et al, 1993). The Cr-O-Si angles and Si-O bond lengths are within the ranges expected in transitionmetal-siloxide complexes (Marciniec & Maciejewski, 2001;Chandrasekhar et al, 2004).…”

Mechanistic Significance of the Si–O–Pd Bond in the Palladium-Catalyzed Cross-Coupling Reactions of Arylsilanolates

“…The only complex that showed a slightly elongated Pd–O bond length is the dppf-derived adduct 10 (2.085 Å), which may be a consequence of the more electron-deficient trifluoromethyl-substituted aryl ring. The Si(1)–O(1) bond lengths of each aryl­palladium­(II) aryl­silanol­ate complex are all consistent with those of previously reported metal silanolate complexes . The trans influence of the aryl group is significant, as the P(2)–Pd(1) bond (2.343 and 2.316 Å) is much longer than the P(1)–Pd(1) bond (2.216 and 2.199 Å).…”

Prediction of 89Y NMR Chemical Shifts in Organometallic Complexes with Density Functional Theory

“…If the average of −24 ppm is used as a starting point for the contribution of a OPR 3 group (R = aryl or alkyl), then the value observed for Y(OSiPh 3 ) 3 (OP n -Bu 3 ) 2 implies that +90 ppm is an appropriate value for OSiPh 3 . This value is consistent with the expectation that alkoxides, with an average contribution of +56 ppm, are better σ-donors than are the corresponding aryl silyloxides 2 Empirical Group Contributions to 89 Y NMR Chemical Shift a groupcontribution (ppm)ref C 5 Me 5 −100 51 OPR 3 (R = aryl or alkyl) −24 this work OCMe 2 i -Pr +12 51 OCMeEt i -Pr +15 51 OCEt 3 +16 51 O-2,6- t -Bu 2 C 6 H 3 +56 51 O-2,6- t -Bu 2 C 6 H 2 -4-Me +57 51 OSiPh 3 +90 this work N(SiMe 3 ) 2 +190 51 CH(SiMe 3 ) 2 +298 51 a Aromatic solvent (benzene or toluene). …”

Bis(tetrahydrofuran-κO)tris(tri-tert-butoxysiloxy)chromium(III)

“…The Cr-O(siloxide) bond lengths are similar to those reported for Cr[OSi(O t Bu) 3 ] 3 -(HNEt 2 ) 2 (Terry et al, 1993). The Cr-O-Si angles and Si-O bond lengths are within the ranges expected in transitionmetal-siloxide complexes (Marciniec & Maciejewski, 2001;Chandrasekhar et al, 2004).…”