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A series of tin(IV) guanidinates were prepared by a (4+1) oxidative cycloaddition of four 1,2-diones (3,5-di-tertbutyl-o-benzoquinone, 3,4,5,6-tetrachloro-1,2-benzoquinone, 9,10-phenanthrenedione, 1,2-diphenylethanedione) or by an oxidative addition of a C−Br bond (from 2-bromo-1,3-diphenylpropane-1,3-dione followed by rearrangement) and a Cl−Cl bond (Cl 2 generated from (dichloro-λ 3 -iodanyl)benzene) with {pTol-NC[N(SiMe 3 ) 2 ]N-pTol} 2 Sn (1). The reactivity of five pentane-1,3-diones and dimethyl malonate with compound 1 was assessed on the basis of the effect of 1,3-diones on the reaction mechanism in comparison with 1,2-diones. In contrast with oxidation reactions observed for compounds containing conjugated CO bonds, the reactions of the tin(II) guanidinate with 1,3-diones revealed a high ability for ligand substitution. All the tin compounds prepared were characterized, and ligand substitution reactions were monitored using 1 H, 13 C, and 119 Sn NMR spectroscopy. The molecular structures of one tin(II) and five tin(IV) guanidinato complexes investigated were determined by Xray diffraction. All tin(IV) compounds display six-or seven-coordination. The UV−vis absorption spectra were recorded and simulated by TDDFT methods in order to get insight into the origin of the nontypical colors of the target tin(IV) diolatoguanidinates and their keto-functionalized precursors.

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Reactions of bis[bis(trimethylsilyl)amino]tin and the dimer of [bis(trimethylsilyl)amino]tin chloride with various carbodiimides give pure corresponding tin(II) guanidinates in essentially quantitative yields. Heteroleptic bis(trimethylsilyl)amido ({R-NC[N(SiMe3)2]N-R}SnN(SiMe3)2)- and chloro-substituted ({R-NC[N(SiMe3)2]N-R}SnCl) tin(II) guanidinates were obtained from reactions of N,N′-diisopropyl-, N,N′-dicyclohexyl-, N,N′-bis(4-methylphenyl)-, and N-[3-(dimethylamino)propyl]-N′-ethylcarbodiimides, respectively. Homoleptic tin(II) guanidinates {R-NC[N(SiMe3)2]N-R}2Sn were obtained from the N,N′-bis(4-methylphenyl)- and N-[3-(dimethylamino)propyl]-N′-ethyl-substituted carbodiimides. Similar reactions of N,N′-bis(2,6-diisopropylphenyl)- and N,N′-bis(trimethylsilyl)carbodiimide, respectively, having the bulkiest substituents of the series, failed to take place under various conditions. The complexes prepared were characterized as monomers in solution by 1H, 13C, and 119Sn NMR spectroscopy in C6D6 and THF-d 8. The solid-state NMR spectra were recorded for structure comparison. X-ray diffraction studies of one homoleptic monomer, two heteroleptic chloro complexes with the structures of two different types of dimers, and the oxidation product of the heteroleptic bis(trimethylsilyl)amido-substituted guanidinatea centrosymmetric (guanidinato)tin(IV) oxidewere performed on appropriate crystals. Attempts to prepare homoleptic types of isopropyl- and cyclohexyl-substituted tin(II) guanidinate complexes were unsuccessful. The structures were also evaluated by DFT methods.

The new class of homo- and heteroleptic n-butyl-N,N'-disubstituted amidinato group 14 metal(II) complexes were prepared by salt elimination from starting lithium amidinates and metal(II) chlorides both in stoichiometric ratio 2:1 and 1:1, respectively. The target amidinates contain less bulky isopropyl or cyclohexyl as well as a sterically demanding aromatic substituent. Desired 1:1 Pb(II) complexes are not accessible by the described procedure. Ligand transfer from Pb to Sn is taking place if homoleptic Pb(II) compounds are reacted with SnCl(2). Prepared tetrylenes were characterized by (1)H, (13)C, (119)Sn and (207)Pb NMR spectroscopy in C(6)D(6) or THF-d(8). X-Ray diffraction studies of one heteroleptic Ge(II) monomeric where the coordination polyhedron of the three coordinated germanium atoms is a trigonal pyramid, two different dimeric structures of heteroleptic Sn(II) complexes, one amidine hydroiodide byproduct and the oxidation product of the heteroleptic chloro Sn(II) amidinate as a tetranuclear species with two Sn(IV) and two Sn(II) atoms in central Sn(2)O(2) planar ring were performed on appropriate single crystals. The dimer of one of the heteroleptic stannylenes reveals a new type of monomeric units connection, weak Sn-Cl contact and an interaction of the tin atom with delocalized N-C(C)-N system of the amidinato ligand of the second molecule.