Aminophosphanes with bulky amino groups: Molecular structure,coupling constants 1J(31P, 15N) and 2J(31P, 29Si), and isotope‐induced chemical shifts 1Δ14/15N(31P)

The preferred conformation of aminophosphanes with bulky amino groups ( 1–20 ) was determined by NMR spectroscopy in solution, in two cases in the solid state ( 11,17 ) and in one case ( 11 ) by X‐ray crystallography. Trimethylsilylaminodiphenylphosphanes Ph₂PN(R)SiMe₃ (R = Bu ( 1 ), Ph ( 2 ), 2‐pyridyl ( 3 ), 2‐pyrimidyl ( 4 ), Me₃Si ( 5 )), amino(chloro)phenylphosphanes Ph(Cl)PNRR′ (R = Bz, R′ = Me ( 6 ), R = Bz, R′ = ^tBu ( 7 ), R = Et, R′ = Ph ( 8 )), amino(chloro)tert‐butylphosphanes ^tBu(Cl)PNRR′ (R = R′ = ⁱPr ( 9 ), R = Me, R′ = ^tBu ( 10 ), R = Bz, R′ = ^tBu ( 11 ), R = H, R′ = ^tBu ( 12 ), R = Et, R′ = Ph ( 13 ), R = ⁱPr, R′ = Ph ( 14 ), R = Bu, R′ = Ph ( 15 ), R = Bz, R′ = Ph ( 16 ), R = R′ = Ph ( 17 ), R = R′ = Me₃Si ( 18 )), 3‐tert‐butyl‐2‐chloro‐1,3,2‐oxazaphospholane ( 19 ), and benzyl(tert‐butyl)aminodichlorophosphane ( 20 ) were studied by ¹H, ¹³C, ¹⁵N, ²⁹Si, and ³¹P NMR spectroscopy. In all cases, the more bulky substituent at the nitrogen atom prefers the syn‐position with respect to the assumed orientation of the phosphorus lone pair of electrons. Many of the derivatives studied adopt this preferred conformation even at room temperature. Numerous signs of coupling constants ¹J(³¹P, ¹⁵N), ²J(³¹P, ¹³C), and ²J(³¹P, ²⁹Si) were determined. Low temperature NMR spectra were measured for derivatives for which rotation about the P N bond at room temperature is fast, showing the presence of two rotamers at low temperature. The respective conformation of these rotamers could be assigned by ¹³C, ¹⁵N, and ³¹P NMR spectroscopy. Isotope‐induced chemical shifts ¹Δ^15/14N(³¹P) were determined for all compounds at natural abundance of ¹⁵N by using Hahn‐echo extended polarization transfer experiments. The molecular structure of 11 in the solid state reveals pyramidal surroundings of the nitrogen atom and mutual trans‐positions of the tert‐butyl groups at phosphorus and nitrogen. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:667–676, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10084     

Kinetics and products of the gas-phase reactions of the OH radical and O3 with allyl chloride and benzyl chloride at room temperature

The kinetics of the gas-phase reactions of allyl chloride and benzyl chloride with the OH radical and O₃ were investigated at 298 ± 2 K and atmospheric pressure. Direct measurements of the rate constants for reactions with ozone yielded values of ??(O₃ + allyl chloride) = (1.60 ± 0.18) × 10^?18 cm³ molecule^?1 s^?1 and ??(O₃ + benzyl chloride) < 6 × 10^?20 cm³ molecule^?1 s^?1. With the use of a relative rate technique and ethane as a scavenger of chlorine atoms produced in the OH radical reactions, rate constants of ??(OH + allyl chloride) = (1.69 ± 0.07) × 10^?11 cm³ molecule^?1 s^?1 and ??(OH + benzyl chloride) = (2.80 ± 0.19) × 10^?12 cm³ molecule^?1 s^?1 were measured. A study of the OH radical reaction with allyl chloride by long pathlength FT-IR absorption spectroscopy indicated that the co-products ClCH₂CHO and HCHO account for ca. 44% of the reaction, and along with the other products HOCH₂CHO, (ClCH₂)₂CO, and CH₂ ? CHCHO account for 84 ± 16% of the allyl chloride reacting. The data indicate that in one atmosphere of air in the presence of NO the chloroalkoxy radical formed following OH radical addition to the terminal carbon atom of the double bond decomposes to yield HOCH₂CHO and the CH₂Cl radical, which becomes a significant source of the Cl atoms involved in secondary reactions. A product study of the OH radical reaction with benzyl chloride identified only benzaldehyde and peroxybenzoyl nitrate in low yields (ca. 8% and ?4%, respectively), with the remainder of the products being unidentified.     

Synthesis and catalytic reactivity of mononuclear substituted tetramethylcyclopentadienyl molybdenum carbonyl complexes

The reactions of five dinuclear carbonyl complexes [(η ⁵-C₅Me₄R)Mo(CO)₃]₂ [R = allyl, ⁿ Bu, ^t Bu, Ph, Bz] with I₂ in chloroform solution gave the corresponding mononuclear substituted tetramethylcyclopentadienyl molybdenum carbonyl complexes [(η ⁵-C₅Me₄R)MoI(CO)₃] [R = allyl (1), ⁿ Bu (2), ^t Bu (3), Ph (4), Bz (5)]. The molecular structures of complexes 2, 3 and 5 were determined by X-ray diffraction analysis. The results show that the substituent in the ring can directly affect the Mo–I bond distances; the more sterically hindered the substituent, the longer the Mo–I bond. Friedel–Crafts reactions of aromatic compounds with a variety of alkylation reagents catalyzed by the complexes showed that all of these mononuclear molybdenum carbonyl complexes have catalytic activity in Friedel–Crafts alkylation reactions. Indeed, compared with traditional catalysts, these mononuclear metal carbonyl complexes have obvious advantages such as higher activities, mild reaction conditions, high selectivity, simple post-processing, and environmentally friendly chemistry.     

Synthesis,structure and ethylene polymerization of group 4 complexes with phosphinoamide ligands

Group 4 complexes containing diphosphinoamide ligands [Ph₂PNR]₂MCl₂ (3: R = ^tBu, M = Ti; 4: R = ^tBu, M = Zr; 5: R = Ph, M = Ti; 6: R = Ph, M = Zr) were prepared by the reaction of MCl₄ (M = Ti; Zr) with the corresponding lithium phosphinoamides in ether or THF. The structure of [Ph₂PN^tBu]₂TiCl₂ (3) was determined by X‐ray crystallography. The phosphinoamides functioned as η²‐coordination ligands in the solid state and the Ti? N bond length suggests it is a simple single bond. In the presence of modified methylaluminoxane or i‐Bu₃Al/Ph₃BC(C₆F₅)₄, catalytic activity of up to 59.5 kg PE/mol cat h bar was observed. Copyright © 2005 John Wiley & Sons, Ltd.     

Functionally substituted organotin compounds I. Addition of thiols to alkenyltin compounds

3-(Trialkylstannyl)propyl aryl sulphides (R₃SnCH₂CH₂CH₂SR′; R = Me, Et, Bu; R′ = Ph, p-tolyl) were prepared by the addition of arenethiols to allyltrialkyltin compounds. Preferential cleavage of the allyl group by the reaction R₃SnCH₂CHCH₂+R′SH→R₃SnSR′+CH₃CHCH₂ occurred when R = R′ = Bu and R = R′ = Ph. Diallyltin dibromide and benzenethiol gave stannous bromide. Mössbauer parameters of the products are recorded.     

Kinetic study on the ligand exchange reactions between bis(alkylxanthato)palladium(II)and bis(N,N-dialkyldithiocarbamato)palladium(II)by high-performance liquid chromatography

The rate constants and equilibrium constants of ligand exchange reactions between his(alkylxanthato)palladium(Ⅱ),Pd(S_2COR)_2(R=Am,n-Hex,Bz),and bis(N,N-dialkyldithiocarbamato)palladium(Ⅱ),Pd(S_2CNR_2)_2(K=Et,n-Pr,n-Bu),in chloroform solution have been determined ina temperature range of 20—50°C by means of high-performance liquid chromatography.It was foundthat both the forward and reverse reactions are of second order.All of the equilibrium constants Kdetermined are 10.3±1.0,much greater than the value(K=4)calculated statistically which indicatesthat the ternary complexes are more stable than the binary complexes.The experimental resultsrevealed that the reaction rate decreases with the increase in the size of R and R~1 groups and the latterare more remarkable,consistent with the deduction of steric effect.The activation parameters ofthe reactions have been calculated.In reaction series(11)and(12)(in the text)the isokinetic tempera-tures B=390±8K and β=346±15 K have been observed respectively.A plausiblemechanism in-volving an eight-membered ring intermediate has been proposed on the basis of experimental results.     

Allylsilane‐Modified Amino Acids from the Claisen Rearrangement

The Claisen rearrangement of the N‐protected, silylated allyl glycinates 11 and 12 led to the formation of allyl/silyl‐functionalized amino acids 13 and 14 in yields up to 80%. The diastereoisomer ratio varied from 2 : 1 to 29 : 1 for 11mb , and from 2 : 1 to 46 : 1 (syn/anti) for 12mb , depending on reaction conditions, as shown by X‐ray crystallographic analysis of 14mb . The relationship between the size of the alkyl groups on the chlorosilane reagent (Me₂R″SiCl, R″=Cl, Me, t‐Bu, Ph) used as an enolate trap and the observed stereoselectivity was investigated in the case of the Ireland–Claisen variant. Me₃SiCl gave the best results. However, the size of the alkyl groups on the silylated ester (Me₂R″Si, R=Me, t‐Bu, Ph, i‐Pr) did not exert a significant effect on the diastereoselectivity or yield of the rearrangement.     

Relative kinetics of the radical addition of benzyl bromide to unsaturated compounds

The relative rate constants of the addition of the C₆H₅CH₂ radical to unsaturated compounds CH₂=CHX (X = C₄H₉, SiMe₃, CF₃, CO₂Me, CN) were determined under the conditions of initiation by the Fe(CO)₅ + DMF system or by benzoyl peroxide. Depending on the values of the relative addition rate constants, the monomers can be arranged into the following series (X): CF₃C₄H₉32Me5 + DMF system, the addition stage proceeds by a free radical mechanism.A. N. Nesmeyanov Institute of Heteroorganic Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 9, pp. 2017–2022, September, 1992.     

Synthesis and Characterization of Three Homoleptic Bismuth Silanolates: [Bi(OSiR3)3] (R = Me,Et, iPr)

The bismuth tris(triorganosilanolates) [Bi(OSiR₃)₃] ( 1 , R = Me; 2 , R = Et; 3 , R = iPr) were prepared by reaction of R₃SiOH with [Bi(OtBu)₃]. Compound 1 crystallizes in the triclinic space group with Z = 2 and the lattice constants a = 10.323(1) Å, b = 13.805(1) Å, c = 21.096(1) Å and α = 91.871(4)°, β = 94.639(3)°, γ = 110.802(3)°. In the solid state compound 1 is a trimer as result of weak intermolecular bismuth‐oxygen interactions with Bi–O distances in the range 2.686(6)–3.227(3) Å. The coordination at the bismuth atoms Bi(1) and Bi(3) is best described as 3 + 2 coordination whereas Bi(2) shows a 3 + 3 coordination. The intramolecular Bi–O distances fall in the range 2.041(3)–2.119(3) Å. Compound 3 crystallizes in the orthorhombic space group Pbcm with Z = 4 and the lattice constants a = 7.201(1) Å, b = 23.367(5) Å and c = 20.893(1) Å, whereas the triethylsilyl‐derivative 2 is liquid. In contrast to [Bi(OSiMe₃)₃] ( 1 ) compound 3 is monomeric in the solid state, but shows similar intramolecular Bi–O distances in the range 1.998(2)–2.065(5) Å. The bismuth silanolates are highly soluble in common organic solvents and strongly moisture sensitive. Compound 1 shows the lowest thermal stability.     

Rate constants for the reactions of benzyl and methyl-substituted benzyl radicals with O2 and NO

Rate constants for reactions of benzyl, o-niethylbenzyl and p-meihylbenzyl radicals with O₂ and NO have been measured at room temperature. The radicals were generated by UV flash photolysis and the time decay measured by absorption at ≈ 300 nm. The rate constants are: benzyl (0.99 ± 0.07 and 9.5 ± 1.2), o-methylbenzyl (1.2 ± 0.07 and 8.6 ± 0.8) and p-mithyl-benzyl (1.1= 0.10 and 8.9 = 0.9) for O₂ and NO respectively in units of 10^?12 cm³ molecule^?1 s^?1.     

Chlorochalcogenation of acetylenes with benzenesulfen-(or selenen)amides and Tin(IV) chloride

Benzenesulfenamides and benzeneselenenamides reacted with terminal and internal acetylenes (hex-1-yne, phenylacetylene, hex-3-yne, but-2-yne-1,4-diol, and diphenylacetylene) in the presence of SnCl₄ to give the corresponding chloroethenyl sulfides and selenides. From symmetric acetylenes, only E isomers (E)-ArXCR=CClR (X = S, Ar = Ph, 4-ClC₆H₄; R = Et, Ph, HOCH₂; X = Se, Ar = Ph, R = Et) were formed. The reactions of benzenesulfenamide with terminal acetylenes, apart from the corresponding Markownikoff and anti-Markownikoff adducts (PhSCH=CClR and PhSCR=CHCl, R = Bu, Ph) gave ethynyl sulfides PhSC=CR (R = Ph, Bu) and cis/trans-isomeric 1,2-bis(phenylsulfanyl)chloroethenes PhSCR=CClSPh (R = Ph, Bu). The results were interpreted assuming intermediate generation of sulfenyl and selenenyl chlorides via reaction of sulfen-and selenenamides with SnCl₄.     

Estimation of rate constants as a function of temperature for the reactions W + XYZ = WX + YZ,where W,X, Y,and Z are H or O atoms

Rate constants have been estimated as a function of temperature for seven reactions of the type W + XYZ = WX + YZ, where W, X, Y, and Z are H and O atoms. From transition state theory and estimates of the heat capacities of activation, where int k is the rate constant per transferable atom for the forward and reverse reactions in the exothermic direction, and where ΔH°_≠298 is in kcal/mol. Values of ΔS°_≠298 and ΔH°_≠298 were obtained from the above equation and previously measured and evaluated rate constants at 298°K. The results are summarized in a table. Rate constants were calculated at temperature from 250 to 2000 K. The estimated rate constants were compared with recommended values. The results for ΔH°_≠298 for reactions (15), (16), (17), and (19), in which a stable intermediate may precede the transition state, together with similar results previously found for reactions X + YZ = XY + Z, suggests that many such reactions may have values of ΔH°_≠298 that are close to zero. The result for the reaction O + O₃ = O₂ + O₂ is however, an exception to the foregoing perhaps because it is the reaction of a singlet with a triplet.ΔS°_≠298 for the same reaction is unexpectedly low.     

Thermodynamic Stability and Physicochemical Characterization of Ligand (4S)‐4‐Benzyl‐3,6,10‐tris(carboxymethyl)‐3,6,10‐triazadodecanedioic Acid (H5[(S)‐4‐Bz‐ttda]) and Its Complexes Formed with Lanthanides,Calcium(II), Zinc(II), and Copper(II) Ions

A derivative of H₅ttda (=3,6,10‐tris(carboxymethyl)‐3,6,10‐triazadodecanedioic acid=N‐{2‐[bis(carboxymethyl)amino]ethyl}‐N‐{3‐[bis(carboxymethyl)amino]propyl}glycine), H₅[(S)‐4‐Bz‐ttda] (=(4S)‐4‐benzyl‐3,6,10‐tris(carboxymethyl)‐3,6,10‐triazadodecanedioic acid=N‐{(2S)‐2‐[bis(carboxymethyl)amino]‐3‐phenylpropyl}‐N‐{3‐[bis(carboxymethyl)amino]propyl}glycine; 1 ) carrying a benzyl group was synthesized and characterized. The stability constants of the complexes formed with Ca²⁺, Zn²⁺, Cu²⁺, and Gd³⁺ were determined by potentiometric methods at 25.0±0.1° and 0.1M ionic strength in Me₄NNO₃. The observed water proton relaxivity value of [Gd{(S)‐4‐Bz‐ttda}]²⁻ was constant with respect to pH changes over the range pH 4.5–12.0. From the ¹⁷O‐NMR chemical shift of H₂O induced by [Dy{(S)‐4‐Bz‐ttda}]²⁻ at pH 6.80, the presence of 0.9 inner‐sphere water molecules was deduced. The water proton spin‐lattice relaxation rate for [Gd{(S)‐4‐Bz‐ttda}]²⁻ at 37.0±0.1° and 20 MHz was 4.90±0.05 mM ⁻¹ s⁻¹. The EPR transverse electronic relaxation rate and ¹⁷O‐NMR transverse‐relaxation time for the exchange lifetime of the coordinated H₂O molecule (τ_M), and ²H‐NMR longitudinal‐relaxation rate of the deuterated diamagnetic lanthanum complex for the rotational correlation time (τ_R) were thoroughly investigated, and the results were compared with those previously reported for the other lanthanide(III) complexes. The exchange lifetime (τ_M) for [Gd{(S)‐4‐Bz‐ttda}]²⁻ (2.3±1.3 ns) was significantly shorter than that of the [Gd(dtpa)(H₂O)]²⁻ complex (dtpa=diethylenetriaminepentaacetic acid). The rotational correlation time τ_R for [Gd{(S)‐4‐Bz‐ttda}]²⁻ (70±6 ps) was slightly longer than that of the [Gd(dtpa)(H₂O)]²⁻ complex. The marked increase of relaxivity of [Gd{(S)‐4‐Bz‐ttda}]²⁻ mainly resulted from its longer rotational time rather than from its fast water‐exchange rate. The noncovalent interaction between human serum albumin (HSA) and the [Gd{(S)‐4‐Bz‐ttda}]²⁻ complex containing the hydrophobic substituent was investigated by measuring the solvent proton relaxation rate of the aqueous solutions. The association constant (K_A) was less than 100 M ⁻¹, indicating a weaker interaction of [Gd{(S)‐4‐Bz‐ttda}]²⁻ with HSA.     

Syntheses,characterizations, and crystal structures of tri‐ and diorganotin (IV) derivatives with 2‐mercapto‐5‐methyl‐1,3,4‐thiadiazole

A series of organotin(IV) complexes with 2‐mercapto‐5‐methyl‐1,3,4‐thiadiazole (HL) of the type R₃ Sn(L) (R = Me 1 ; Bu 2 ; Ph 3 ; PhCH₂ 4 ) and R₂Sn(L)₂ (R = CH₃ 5 ; Ph 6 ; PhCH₂ 7 ; Bu 8 ) have been synthesized. All complexes 1–8 were characterized by elemental analysis, IR,¹H, ¹³ C, and ¹¹⁹Sn NMR spectra. Among these, complexes 1 , 3 , 4 , and 7 were also determined by X‐ray crystallography. The tin atoms of complexes 1 , 3 , and 4 are all penta‐coordinated and the geometries at tin atoms of complexes 3 and 4 are distorted trigonal–bipyramidal. Interestingly, complex 1 has formed a 1D polymeric chain through Sn and N intermolecular interactions. The tin atom of complex 7 is hexa‐coordinated and its geometry is distorted octahedral. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:353–364, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20215     

Synthesis and polymerization behavior of novel C 1 and C s titanium ansa‐cyclopentadienyl‐amido catalysts for ethylene and propylene polymerization

Four titanium ansa‐cyclopentadienyl‐amido complexes of the general formula [C₅H₃RMe₂SiN(2,6‐Me₂C₆H₃)]TiX₂(R = H,Me,Bz,^tBu;X = NMe₂ or Cl) have been synthesized. The complexes polymerize both ethylene and propylene in the presence of methylaluminoxane or Ph₃CB(C₆F₅)₄–triisobutylaluminum and were most active at lower temperatures. In general, the smaller the substituent on the cyclopentadienyl group, the more active the catalyst. The catalysts were found to be poorly stereoselective for the polymerization of polypropylene, with the tertiary‐butyl substituted catalyst giving a polymer with the greatest [mmmm] (14.2%). The structure of [C₅H₄Me₂SiN(2,6‐Me₂C₆H₃)] Ti(NMe₂)₂ was determined by X‐ray diffraction. The complex crystallizes in the monoclinic system space group P2₁/n, with a = 16.437(2), b = 8.652(3), c = 16.494(4),β = 117.54(2) and Z = 4. Copyright © 2002 John Wiley & Sons, Ltd.     

Relations between the electrosorption and the inhibition behaviour of homologous dialkyl-phenyl-phosphine oxides

The electrode transfer reaction of Cd²⁺ has been studied under the influence of the homologous dialkyl-phenyl-phosphine oxides (R)₂·C₆H₅·PO (R=CH₃, C₂H₅, C₃H₇, C₄H₉, C₅H₁₁) using d.c. polarography. The rate constants were correlated with the adsorption data. The comparison of the rate constants with the surface pressure values shows that the rate constants decrease linearly with increasing surface pressure values. It could also be shown that the inhibitory effect grows as the length of the alkyl groups increases.     

Syntheses,structures and catalytic activity for Friedel-Crafts reactions of substituted indenyl rhenium carbonyl complexes

The complexes [(η⁵-C₉H₆R)Re(CO)₃] [R = ⁿBu (8), ^tBu (9), CH(CH₂)₄ (10), Ph (11), Bz (12), 4-methoxyphenyl (13), 4-chlorophenyl (14)] were synthesized by refluxing substituted indenyl ligands [C₉H₇R] [R = ⁿBu (1), ^tBu (2), CH(CH₂)₄ (3), Ph (4), Bz (5), 4-methoxyphenyl (6), 4-chlorophenyl (7)], and Re₂(CO)₁₀ in decalin. The molecular structures of 9, 10, 12, and 13 were determined by X-ray diffraction analysis. These four crystals have similar molecular structures of the mononuclear carbonyl complex. In each of these molecules, Re is η⁵-coordinated to the five-membered ring of the indenyl group. Complexes 8–14 have catalytic activity for Friedel-Crafts reactions of aromatic compounds with a variety of alkylation and acylation reagents. Compared with traditional catalysts, these mononuclear metal carbonyl complexes have obvious advantages such as high activities, mild reaction conditions, high selectivity, and environmentally friendly chemistry.     

Hydrosilylation of Allyl Ethers in the Presence of Supported Sulfur-Containing Platinum(II) Complexes

Hydrosilylation of allyl ethyl, allyl butyl, allyl glycidyl, allyl benzyl, and allyl phenyl ethers by 1,1,3,3-tetramethyldisiloxane in the presence of supported sulfur-containing platinum(II) complexes with the general formula [{SiO₂}O_2Si(Me)(CH₂)₃SR]₂PtCl₂ (R = Bu, Hex, Bn; {SiO₂} is silica surface) and side processes have been studied.     

Synthesis, Characterization and Biological Activity of Diorganotin（IV） Complexes of N-（3,5-Dibromosalicylidene）-α-amino Acid

The diorganotin（Ⅳ） complexes of N-（3,5-dibromosalicylidene）-α-amino acid, R2Sn（2-O-3,5-Br2C6H2CH= NCHRCOO）（where R=H, Me, i-Pr, Bz; R＇=n-Bu, Cy）, were synthesized by the reactions of diorganotin dichlorides with in situ formed potassium salt of N-（3,5-dibromosalicylidene）-α-amino acid and characterized by elemental analysis, IR and NMR （^1H, ^13C and ^119Sn） spectra. The crystal structures of n-Bu2Sn（2-O-3,5-Br2C6H2CH= NCHRCOO）（R=i-Pr, Bz） and Cy2Sn（2-O-3,5-Br2C6H2CH=NCHRCOO）（R=Me, Bz） were determined by X-ray single crystal diffraction and showed that the tin atoms are in a distorted trigonal bipyramidal geometry to form five- and six-membered chelate rings with the tridentate ligand. Bioassay results indicated that the compounds possess better in vitro antitumour activity against three human tumour cell lines, HeLa, CoLo205 and MCF-7, than cis-platin and moderate anti-bacterial activity against two bacteria, E. coli and S. aureus.     

Stable N‐Heterocyclic Germylenes of the Type [Fe{(η5‐C5H4)NR}2Ge] and Their Oxidation Reactions with Sulfur,Selenium, and Diphenyl Diselenide

Three new N‐heterocyclic germylenes of the type [Fe{(η⁵‐C₅H₄)NR}₂Ge] ( 1R Ge) containing particularly bulky alkyl [R = 2‐adamantyl (Ad), 1,1,2,2‐tetramethylpropyl (Pr*)] or aryl substituents [R = 2,6‐diisopropylphenyl (Dipp)] were prepared and structurally characterized, in two cases (R = Ad, Dipp), by single‐crystal X‐ray diffraction. Together with the previously described homologues with R = trimethylsilyl (TMS), tert‐butyl (tBu), and mesityl (Mes) their oxidative addition reactions with S₈ and Se₈ were studied, which afforded compounds of the type [ 1R Ge(μ‐E)]₂ (E = S, Se). The low solubility of most of these products severely hampered their purification and characterization. Nevertheless, their structural characterization by single‐crystal X‐ray diffraction was possible in six cases (E = S, R = Ad, Pr*; E = Se, R = Ad, Pr*, Mes, Dipp). No solubility problems were encountered in oxidative addition reactions with diphenyl diselenide, affording products of the type 1R Ge(SePh₂)₂, whose crystal structures could be determined in four cases (R = TMS, tBu, Mes, Dipp). Short intramolecular CH ··· Se contacts compatible with hydrogen bonds were observed for [ 1Ad Ge(μ‐Se)]₂, [ 1Pr* Ge(μ‐Se)]₂, and 1tBu Ge(SePh₂)₂.