Reactivity of NHI-Stabilized Heavier Tetrylenes towards CO and N O.

A heteroleptic amino(imino)stannylene (TMS N)(I BuN)Sn: (TMS=trimethylsilyl, I Bu=C[(N- Bu)CH] ) as well as two homoleptic NHI-stabilized tetrylenes, (I BuN) E: (NHI=N-heterocyclic imine, E=Ge, Sn) are presented. VT-NMR investigations of (I BuN) Sn: (2) reveal an equilibrium between the monomeric stannylene at room temperature and the dimeric form at -80 °C as well as in the solid state. Upon reaction of the homoleptic tetrylenes with CO , both compounds insert two equivalents of CO , however differing bonding modes can be observed.

Recent advances of group 14 dimetallenes and dimetallynes in bond activation and catalysis.

Since the first heavy alkene analogues of germanium and tin were isolated in 1976, followed by West's disilene in 1981, the chemistry of stable group 14 dimetallenes and dimetallynes has advanced immensely. Recent developments in this field veered the focus from the isolation of novel bonding motifs to mimicking transition metals in their ability to activate small molecules and perform catalysis. The potential of these homonuclear multiply bonded compounds has been demonstrated numerous times in the activation of H, NH, CO and other small molecules.

Time delay in the swing equation: A variety of bifurcations.

The present paper addresses the swing equation with additional delayed damping as an example for pendulumlike systems. In this context, it is proved that recurring sub- and supercritical Hopf bifurcations occur if time delay is increased. To this end, a general formula for the first Lyapunov coefficient in second order systems with additional delayed damping and delay-free nonlinearity is given.

Elementary school classroom physical activity breaks: student, teacher, and facilitator perspectives.

Current physical activity (PA) guidelines recommend that children accumulate at least 60 min of PA each day, and that adults should collaborate across sectors to increase opportunities for PA. Implementing brief classroom PA breaks (CPABs) is one way to help increase daily PA. The primary purpose of this study was to determine perceptions of a 14-wk CPAB program among elementary school children, in the first through fourth grades ( n = 254), at a suburban elementary school, and their teachers ( n = 18).