We report here the synthesis of new C,N-chelated chlorostannylenes and germylenes L(3) MCl (M=Sn(1), Ge (2)) and L(4) MCl (M=Sn(3), Ge (4)) containing sterically demanding C,N-chelating ligands L(3, 4) (L(3) =[2,4-di-tBu-6-(Et2 NCH2 )C6 H2 ](-) ; L(4) =[2,4-di-tBu-6-{(C6 H3 -2',6'-iPr2 )N=CH}C6 H2 ](-) ). Reductions of 1-4 yielded three-coordinate C,N-chelated distannynes and digermynes [L(3, 4) M]2 for the first time (5: L(3) , M=Sn, 6: L(3) , M=Ge, 7: L(4) , M=Sn, 8: L(4) , M=Ge). For comparison, the four-coordinate distannyne [L(5) Sn]2 (10) stabilized by N,C,N-chelate L(5) (L(5) =[2,6-{(C6 H3 -2',6'-Me2 )NCH}2 C6 H3 ](-) ) was prepared by the reduction of chlorostannylene L(5) SnCl (9). Hence, we highlight the role of donor-driven stabilization of tetrynes. Compounds 1-10 were characterized by means of elemental analysis, NMR spectroscopy, and in the case of 1, 2, 5-7, and 10, also by single-crystal X-ray diffraction analysis. The bonding situation in either three- or four-coordinate distannynes 5, 7, and 10 was evaluated by DFT calculations. DFT calculations were also used to compare the nature of the metal-metal bond in three-coordinate C,N-chelating distannyne [L(3) Sn]2 (5) and related digermyme [L(3) Ge]2 (6).

Our attempts to synthesize the N→Si intramolecularly coordinated organosilanes Ph2 L(1) SiH (1 a), PhL(1) SiH2 (2 a), Ph2 L(2) SiH (3 a), and PhL(2) SiH2 (4 a) containing a CH=N imine group (in which L(1) is the C,N-chelating ligand {2-[CH=N(C6 H3 -2,6-iPr2)]C6 H4}(-) and L(2) is {2-[CH=N(tBu)]C6 H4}(-)) yielded 1-[2,6-bis(diisopropyl)phenyl]-2,2-diphenyl-1-aza-silole (1), 1-[2,6-bis(diisopropyl)phenyl]-2-phenyl-2-hydrido-1-aza-silole (2), 1-tert-butyl-2,2-diphenyl-1-aza-silole (3), and 1-tert-butyl-2-phenyl-2-hydrido-1-aza-silole (4), respectively. Isolated organosilicon amides 1-4 are an outcome of the spontaneous hydrosilylation of the CH=N imine moiety induced by N→Si intramolecular coordination. Compounds 1-4 were characterized by NMR spectroscopy and X-ray diffraction analysis. The geometries of organosilanes 1 a-4 a and their corresponding hydrosilylated products 1-4 were optimized and fully characterized at the B3LYP/6-31++G(d,p) level of theory. The molecular structure determination of 1-3 suggested the presence of a Si-N double bond. Natural bond orbital (NBO) analysis, however, shows a very strong donor-acceptor interaction between the lone pair of the nitrogen atom and the formal empty p orbital on the silicon and therefore, the calculations show that the Si-N bond is highly polarized pointing to a predominantly zwitterionic Si(+) N(-) bond in 1-4. Since compounds 1-4 are hydrosilylated products of 1 a-4 a, the free energies (ΔG298), enthalpies (ΔH298), and entropies (ΔH298) were computed for the hydrosilylation reaction of 1 a-4 a with both B3LYP and B3LYP-D methods. On the basis of the very negative ΔG298 values, the hydrosilylation reaction is highly exergonic and compounds 1 a-4 a are spontaneously transformed into 1-4 in the absence of a catalyst.

The monomeric tin­(II) hydride L2(H)­Sn·W­(CO)5 (2), where L2 is 2-Et2NCH2-4,6-tBu2-C6H2, was easily transformed to the nonsymmetrical distannyne L1SnSnL2·W­(CO)5 (4), where L1 is 2,6-(Me2NCH2)2C6H3, by an amine elimination reaction with the tin­(II) amide L1SnNEt2 (3), without additional initiators such as N-bases or NHC carbenes. DFT calculations showed that the substitution of an SnH atom by an SnL1 fragment strongly affects the L2SnW­(CO)5 fragment, which accumulates a larger amount of electron density.

A set of neutral and ionic ruthenium arene trichlorostannyl complexes are reported herein. The tin(II) compounds L 1 SnCl {1; L 1 = [2-(CH 2 NEt 2 )-4,6-(tBu) 2 C 6 H 2 ] -} and [L 2 SnCl][SnCl 3 ] {2; L 2 = 2,6-[(CH 3 )C=N(C 6 H 3 -2,6-iPr 2 ) 2 ]C 5 H 3 N} showed a rather different reactivity towards the ruthenium complex [(η 6cymene)RuCl] 2 (η-Cl) 2 . As a consequence, the neutral complex [Ru(η 6 -cymene)(L 1 SnCl)Cl 2 ] (4) and the ionic compound [L 2 SnCl][Ru(η 6 -cymene)(SnCl 3 ) 2 Cl] (8) were isolated. The insertion reaction of 4 with SnCl 2 provided the neutral trimetallic ruthenium complex [Ru(η 6 -cymene)(L 1 SnCl)(SnCl 3 )Cl] (6). Analo- [a]

The synthesis of the C,N-chelated homoleptic organotetrylenes (L 1 ) 2 E (1, E = Sn; 2, E = Pb) and of the tungsten pentacarbonyl complex (L 1 ) 2 SnW(CO) 5 (3), containing the sterically demanding C,N-chelating ligand L2 )N C(Me)}C 6 H 2 (OCH 2 O)] − ) provided either the homoleptic stannylene (L 2 ) 2 Sn (4) or the C,Nchelated chlorostannylene (L 2 )SnCl ( 5). All attempts to convert the latter into the corresponding ditin compound [L 2 Sn] 2 failed, however, and resulted in the isolation of 4 and elemental tin. These attempts also provided the unprecedented complex [2-{(C 6 H 3 -2,6-Pr i 2 )NC(Me)}C 6 H 2 (OCH 2 O)][2-{(C 6 H 3 -2,6-Pr i 2 )NHCH(Me)}C 6 H 2 (OCH 2 O)]Sn (6).