A Zirconium Hydrazide as a Synthon for a Metallanitrene Equivalent: Atom‐by‐Atom Assembly of [EN₂]²⁻ Units (E=S, Se) by Chalcogen‐Atom Transfer in the Coordination Sphere of a Transition Metal

Zirconium and Hafnium Hydrazinediido Half-Sandwich Complexes: Synthesis and Reactivity

“…Both M(1)–N(3) and N(3)–N(4) bond lengths (mean values for 3a , Zr(1)–N(3) 1.875 Å and N(3)–N(4) 1.379 Å, mean values for 3b , Hf(1)–N(3) 1.856 Å and N(3)–N(4) 1.389 Å, respectively) are in good agreement with those of previously reported zirconium hydrazinediido complexes, as is the slight deviation from linearity for the M(1)–N(3)–N(4) units (mean values Zr(1)–N(3)–N(4) 171.7° and Hf(1)–N(3)–N(4) 171.3°, respectively). − , In both cases, the 2-( N -xylylamino)pyrrolinato ligand is bound in a κ 2 mode similarly to the analogous titanium complex, while the Zr(1)–N(1)/N(2) distances (mean values 2.306 and 2.293 Å) as well as the Hf(1)–N(1)/N(2) distances (2.272 and 2.270 Å) areas expectedlonger than those for comparable titanium complexes (mean values 2.273 and 2.265 Å) …”

Zirconium and Hafnium Hydrazinediido Half-Sandwich Complexes: Synthesis and Reactivity

“…Both M(1)–N(3) and N(3)–N(4) bond lengths (mean values for 3a , Zr(1)–N(3) 1.875 Å and N(3)–N(4) 1.379 Å, mean values for 3b , Hf(1)–N(3) 1.856 Å and N(3)–N(4) 1.389 Å, respectively) are in good agreement with those of previously reported zirconium hydrazinediido complexes, as is the slight deviation from linearity for the M(1)–N(3)–N(4) units (mean values Zr(1)–N(3)–N(4) 171.7° and Hf(1)–N(3)–N(4) 171.3°, respectively). − , In both cases, the 2-( N -xylylamino)pyrrolinato ligand is bound in a κ 2 mode similarly to the analogous titanium complex, while the Zr(1)–N(1)/N(2) distances (mean values 2.306 and 2.293 Å) as well as the Hf(1)–N(1)/N(2) distances (2.272 and 2.270 Å) areas expectedlonger than those for comparable titanium complexes (mean values 2.273 and 2.265 Å) …”

Titanium Hydrazides Supported by Diamide-Amine and Related Ligands: A Combined Experimental and DFT Study

“…The weakening of the N α −N β bond is an important aspect of metal hydrazide chemistry from the point of view of its eventual cleavage. Several reports from group 4 have found facile cleavage of this bond, especially in π-loaded systems. ,, Experimentally ( 2 − 12 ) and computationally it is found that rotation of the amide lone pairs results in a slightly longer N α −N β distance (Δ ≈ 0.01 Å). Furthermore, the model Hyd_0_rot shows a further ca .…”

M═Nα Cycloaddition and Nα−Nβ Insertion in the Reactions of Titanium Hydrazido Compounds with Alkynes: A Combined Experimental and Computational Study

“…t Bu) 2 ). 42 Mindiola's mechanism is consistent with our experimental evidence for a pyridine-free intermediate being formed before reaction with the alkyne. Furthermore, if the intramolecular transformation IV f V were the rate-limiting step, then the experimental near-zero entropy of activation for 11 + PhCCMe f 13 could likewise be consistent with Pathway A.…”

“…Ring-opening of the azirine via NPh 2 group transfer from Ti back to C R′ affords the four-coordinate insertion product V which is then trapped by pyridine giving VI . Gade has also proposed a similar η 2 -hydrazido intermediate in the N α −N β cleavage reaction of Zr(N 2 *N py )(NNPh 2 )(py) with isocyanides (N 2 *N py = (2-NC 5 H 4 )CMe(CH 2 NSiMe 2 t Bu) 2 ) . Mindiola’s mechanism is consistent with our experimental evidence for a pyridine-free intermediate being formed before reaction with the alkyne.…”

Zirconium and Hafnium Hydrazinediido Half-Sandwich Complexes: Synthesis and Reactivity

“…Both M(1)–N(3) and N(3)–N(4) bond lengths (mean values for 3a , Zr(1)–N(3) 1.875 Å and N(3)–N(4) 1.379 Å, mean values for 3b , Hf(1)–N(3) 1.856 Å and N(3)–N(4) 1.389 Å, respectively) are in good agreement with those of previously reported zirconium hydrazinediido complexes, as is the slight deviation from linearity for the M(1)–N(3)–N(4) units (mean values Zr(1)–N(3)–N(4) 171.7° and Hf(1)–N(3)–N(4) 171.3°, respectively). − , In both cases, the 2-( N -xylylamino)pyrrolinato ligand is bound in a κ 2 mode similarly to the analogous titanium complex, while the Zr(1)–N(1)/N(2) distances (mean values 2.306 and 2.293 Å) as well as the Hf(1)–N(1)/N(2) distances (2.272 and 2.270 Å) areas expectedlonger than those for comparable titanium complexes (mean values 2.273 and 2.265 Å) …”

Titanium Hydrazides Supported by Diamide-Amine and Related Ligands: A Combined Experimental and DFT Study

“…The weakening of the N α −N β bond is an important aspect of metal hydrazide chemistry from the point of view of its eventual cleavage. Several reports from group 4 have found facile cleavage of this bond, especially in π-loaded systems. ,, Experimentally ( 2 − 12 ) and computationally it is found that rotation of the amide lone pairs results in a slightly longer N α −N β distance (Δ ≈ 0.01 Å). Furthermore, the model Hyd_0_rot shows a further ca .…”

M═Nα Cycloaddition and Nα−Nβ Insertion in the Reactions of Titanium Hydrazido Compounds with Alkynes: A Combined Experimental and Computational Study

“…t Bu) 2 ). 42 Mindiola's mechanism is consistent with our experimental evidence for a pyridine-free intermediate being formed before reaction with the alkyne. Furthermore, if the intramolecular transformation IV f V were the rate-limiting step, then the experimental near-zero entropy of activation for 11 + PhCCMe f 13 could likewise be consistent with Pathway A.…”

“…Ring-opening of the azirine via NPh 2 group transfer from Ti back to C R′ affords the four-coordinate insertion product V which is then trapped by pyridine giving VI . Gade has also proposed a similar η 2 -hydrazido intermediate in the N α −N β cleavage reaction of Zr(N 2 *N py )(NNPh 2 )(py) with isocyanides (N 2 *N py = (2-NC 5 H 4 )CMe(CH 2 NSiMe 2 t Bu) 2 ) . Mindiola’s mechanism is consistent with our experimental evidence for a pyridine-free intermediate being formed before reaction with the alkyne.…”

Zirconium and Hafnium Hydrazinediido Half-Sandwich Complexes: Synthesis and Reactivity

“…Both M(1)–N(3) and N(3)–N(4) bond lengths (mean values for 3a , Zr(1)–N(3) 1.875 Å and N(3)–N(4) 1.379 Å, mean values for 3b , Hf(1)–N(3) 1.856 Å and N(3)–N(4) 1.389 Å, respectively) are in good agreement with those of previously reported zirconium hydrazinediido complexes, as is the slight deviation from linearity for the M(1)–N(3)–N(4) units (mean values Zr(1)–N(3)–N(4) 171.7° and Hf(1)–N(3)–N(4) 171.3°, respectively). − , In both cases, the 2-( N -xylylamino)pyrrolinato ligand is bound in a κ 2 mode similarly to the analogous titanium complex, while the Zr(1)–N(1)/N(2) distances (mean values 2.306 and 2.293 Å) as well as the Hf(1)–N(1)/N(2) distances (2.272 and 2.270 Å) areas expectedlonger than those for comparable titanium complexes (mean values 2.273 and 2.265 Å) …”

Titanium Hydrazides Supported by Diamide-Amine and Related Ligands: A Combined Experimental and DFT Study

“…The weakening of the N α −N β bond is an important aspect of metal hydrazide chemistry from the point of view of its eventual cleavage. Several reports from group 4 have found facile cleavage of this bond, especially in π-loaded systems. ,, Experimentally ( 2 − 12 ) and computationally it is found that rotation of the amide lone pairs results in a slightly longer N α −N β distance (Δ ≈ 0.01 Å). Furthermore, the model Hyd_0_rot shows a further ca .…”

M═Nα Cycloaddition and Nα−Nβ Insertion in the Reactions of Titanium Hydrazido Compounds with Alkynes: A Combined Experimental and Computational Study

“…t Bu) 2 ). 42 Mindiola's mechanism is consistent with our experimental evidence for a pyridine-free intermediate being formed before reaction with the alkyne. Furthermore, if the intramolecular transformation IV f V were the rate-limiting step, then the experimental near-zero entropy of activation for 11 + PhCCMe f 13 could likewise be consistent with Pathway A.…”

“…Ring-opening of the azirine via NPh 2 group transfer from Ti back to C R′ affords the four-coordinate insertion product V which is then trapped by pyridine giving VI . Gade has also proposed a similar η 2 -hydrazido intermediate in the N α −N β cleavage reaction of Zr(N 2 *N py )(NNPh 2 )(py) with isocyanides (N 2 *N py = (2-NC 5 H 4 )CMe(CH 2 NSiMe 2 t Bu) 2 ) . Mindiola’s mechanism is consistent with our experimental evidence for a pyridine-free intermediate being formed before reaction with the alkyne.…”